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The impact of computed tomography on the utilization of neurological tests at a community hospital Cheung, Ignatius W. K. 1986

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THE IMPACT OF COMPUTED TOMOGRAPHY ON THE UTILIZATION OF NEUROLOGICAL TESTS AT A COMMUNITY HOSPITAL by IGNATIUS W.K. CHEUNG M.B..B.S., The U n i v e r s i t y of Sydney, 1971 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF HEALTH CARE AND EPIDEMIOLOGY HEALTH SERVICES PLANNING AND ADMINISTRATION PROGRAM We a c c e p t t h i s t h e s i s as conforming to the r e q u i r e d s t a n d a r d MASTER OF SCIENCE i n THE UNIVERSITY OF BRITISH COLUMBIA March 1986 © I g n a t i u s Cheung 1986 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Health Care & Epidemiology The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date 21st A p r i l , 1966 Ignatius Cheu; DE-6(3/81) ABSTRACT One of the major i s s u e s i n the h e a l t h c a r e i n d u s t r y i s the c o n t i n u a l r i s e i n t o t a l h e a l t h c a r e e x p e n d i t u r e s r e l a t i v e to the Gross N a t i o n a l P r o d u c t . A s i g n i f i c a n t p o r t i o n of t h i s r i s e has been a t t r i b u t e d t o the i n c r e a s i n g use of m e d i c a l t e c h n o l o g i e s . As an i n c r e a -s i n g number of t e c h n o l o g i c a l i n n o v a t i o n s are b e i n g d eveloped f o r h e a l t h c a r e , and such new t e c h n o l o g i e s are o f t e n c o m p l i c a t e d and e x p e n s i v e , the need f o r p r o p e r l y conducted e v a l u a t i v e s t u d i e s becomes very i m p o r t a n t . I t i s e s s e n t i a l to know whether a new t e c h n o l o g y i s a s u b s t i t u t e f o r l e s s e f f e c t i v e ones or i s merely an add-on. C l e a r g u i d e l i n e s on under what c o n d i t i o n s the new t e c h n o -l o g y i s a p p l i c a b l e s h o u l d be d e v e l o p e d . For a d i a g n o s t i c t e c h n o l o g y , the i d e a l model of e v a l u a t i o n s h o u l d i n v o l v e assessments of t e c h n i c a l c a p a b i l i t y and s a f e t y , d i a g n o s t i c a c c u r a c y , d i a g n o s t i c i m p a c t , t h e r a p e u t i c i m p a c t , p a t i e n t outcome, economic impact and a v a i l a b i l i t y . In the r e l a t i v e l y s h o r t p e r i o d s i n c e 1971, when computed tomography (CT) was f i r s t used c l i n i c a l l y , i t has become an i m p o r t a n t p a r t of m e d i c a l p r a c t i c e . T h i s study a t t e m p t s to a s s e s s the impact of CT on the u t i l i z a t i o n of r e l a t e d n e u r o l o g i c a l t e s t s a t the L i o n s Gate H o s p i t a l . T h i s i s a community h o s p i t a l s e r v i n g a p o p u l a t i o n of a p p r o x i m a t e l y 140,000 p e o p l e . i i This study i s a retrospective, before-after comparison of the u t i l i z a t i o n of neurological tests before and after • the introduction of CT. Two groups of neurological patients, who were hospitalized during the study period 1973 to 1983/4, were assessed. These were the brain tumour group (ICD-9: 191, 198 and 225) and the cerebrovascular disease group (ICD-9: 430 to 438). The results of th i s study suggest that, for both groups of patients, CT i s a complete replacement for pneumoencephalography and nuclear brain scanning, and i s a p a r t i a l replacement for electroencephalography and plain s k u l l radiography. However, CT has had l i t t l e impact on cerebral angiography which f e l l marginally in the brain tumour group and rose s i g n i f i c a n t l y in the cerebrovascular disease group. It has also been estimated that, over the study period, the average t o t a l cost of neurological tests (based on 1983/4 f e e - d o l l a r s ) , on a per patient basis, remained the same for the brain tumour group but rose by 92% for the cerebrovascular disease group. i i i TABLE OF CONTENTS ABSTRACT i i LIST OF TABLES v i LIST OF FIGURES . v i i ACKNOWLEDGEMENT v i i i CHAPTER 1 : INTRODUCTION 1 CHAPTER 2 : LITERATURE REVIEW: ALLOCATION OF RESOURCES AND EVALUATION OF MEDICAL TECHNOLOGY 2.1 I n t r o d u c t i o n 5 2.2 Resource A l l o c a t i o n 6 2.3 E v a l u a t i o n of M e d i c a l Technology 10 CHAPTER 3 : LITERATURE REVIEW: EVALUATION OF COMPUTED TOMOGRAPHY 3.1 I n t r o d u c t i o n 19 3.2 T e c h n i c a l c a p a b i l i t y and s a f e t y 20 of computed tomography 3.3 D i f f u s i o n of Computed Tomography 24 3.4 Impact of Computed Tomography on 32 N e u r o l o g i c a l T e s t s i v CHAPTER 4 : METHODOLOGY 4.1 I n t r o d u c t i o n 47 4.2 S e t t i n g 47 4.3 Study Design 48 4.4 Study P e r i o d s 49 4.5 Study P o p u l a t i o n 50 4.6 Data Source and C o l l e c t i o n 53 4.7 S t a t i s t i c a l A n a l y s i s 54 CHAPTER 5 : RESULTS 5.1 I n t r o d u c t i o n 56 5.2 P r o v i n c i a l Data 56 5.3 I n s t i t u t i o n a l Data 59 5.4 Study Group C h a r a c t e r i s t i c s 62 5.5 Frequency of N e u r o l o g i c a l T e s t s 66 i n Study Groups 5.6 Impact on T o t a l Cost of 72 N e u r o l o g i c a l T e s t s CHAPTER 6 : DISCUSSION AND CONCLUSION 6.1 E f f e c t of CT on N e u r o l o g i c a l 78 T e s t s 6.2 E f f e c t of CT on L i o n s Gate 83 H o s p i t a l 6.3 Study L i m i t a t i o n s 85 6.4 C o n c l u s i o n 89 REFERENCES 94 APPENDIX A: CALCULATION OF SAMPLE SIZE 100 APPENDIX B: PATIENT CHART EXTRACT FORM 101 v LIST OF TABLES 1 N a t i o n a l H e a l t h E x p e n d i t u r e of Canada, 1961-82. 1 D i s t r i b u t i o n of CT Scanners i n the U n i t e d S t a t e s ( 1 980). 2 D i s t r i b u t i o n of CT Scanners i n Canada ( 1 9 8 4 ) . 1 Study P e r i o d s . 2 Study Groups. 3 S i z e of Study Groups. 1 N e u r o l o g i c a l A d m i s s i o n s f o r P r o v i n c e of B r i t i s h Columbia. 2 Number of F i r s t - A d m i s s i o n N e u r o l o g i c a l P a t i e n t s . 3 Frequency of N e u r o - D i a g n o s t i c T e s t s a t LGH. 4 H o s p i t a l i z e d B r a i n Tumour P a t i e n t s (ICD-9: 191, 198 and 225). 5 H o s p i t a l i z e d C e r e b r o v a s c u l a r D i s e a s e P a t i e n t s (ICD-9: 430 to 438). 6 Frequency of N e u r o l o g i c a l T e s t s i n the B r a i n Tumour Group. 7 Frequency of N e u r o l o g i c a l T e s t s i n the C e r e b r o -v a s c u l a r D i s e a s e Group. 8 S t a t i s t i c a l A n a l y s e s of O v e r a l l Changes i n Frequency of U t i l i z a t i o n of N e u r o l o g i c a l T e s t s (1973 - 1983/4). 9 Fee Schedule of N e u r o l o g i c a l D i a g n o s t i c P r o c e d u r e s . 10 Average Cost of N e u r o l o g i c a l T e s t s per B r a i n Tumour P a t i e n t ( i n 1983/4 f e e - d o l l a r s ) . 11 Average Cost of N e u r o l o g i c a l T e s t s per C e r e b r o -v a s c u l a r D i s e a s e P a t i e n t ( i n 1983/4 f e e - d o l l a r s ) . 12 T o t a l Cost of N e u r o l o g i c a l T e s t s a t L i o n s Gate H o s p i t a l ( i n 1983/4 f e e - d o l l a r s ) . v i LIST OF FIGURES 3.1 Cumulative Number of CT Scanners Installed 25 in the United States (1973-1980). 4.1 Study Design. 49 v i i ACKNOWLEDGEMENT I am deeply grateful to the members of my thesis advisory committee, without whose help this thesis would not have been possible. I am greatly indebted to Dr. Samuel Sheps, Chairman of the committee, for helping me in designing t h i s study, and for his patient guidance throughout the preparation of the thesis. I am also grateful to Dr. Robert G. Evans and Dr. Martin Schechter, members of the committee, for their invaluable advice and support. I would also l i k e to express my sincere appre-ci a t i o n for the help and cooperation provided by the st a f f of the Lions Gate Hospital. In pa r t i c u l a r , I wish to thank Mr. John Borthwick, Dr. James Corbett, Mrs. V i c k i Tich-bourne, Miss Diane Lane and Mr. John Logan. F i n a l l y , I wish to thank my friend M.S. Lau for typing this thesis. v i i i CHAPTER 1 INTRODUCTION Du r i n g the 1960's and e a r l y 1970's, the p r i m a r y g o a l of h e a l t h p o l i c y i n i n d u s t r i a l i z e d c o u n t r i e s was to 1 improve a c c e s s t o h e a l t h c a r e , e s p e c i a l l y f o r the poor. A l t h o u g h t h i s remains an i m p o r t a n t g o a l , a t t e n t i o n has been s h i f t e d i n the d i r e c t i o n of c o s t containment and r e s o u r c e a l l o c a t i o n . I n p a r t i c u l a r , d i s c u s s i o n has c e n t r e d on the e f f e c t of new m e d i c a l t e c h n o l o g i e s on the c o s t s of p a t i e n t c a r e , and on the be s t a l l o c a t i o n of l i m i t e d r e s o u r c e s among competing uses to p r o v i d e the o p t i m a l 2 h e a l t h b e n e f i t f o r our s o c i e t y . M e d i c a l t e c h n o l o g y i s f r e q u e n t l y seen as one of the c u l p r i t s i n the r i s i n g c o s t of h e a l t h c a r e . However, 1 Banta r a i s e s the p o i n t t h a t : "While t h e r e i s much i n m e d i c a l c a r e t h a t c o u l d be c ut w i t h l i t t l e impact on p a t i e n t outcome, we must be very c a r e f u l not to cut those s e r v i c e s t h a t a r e of v a l u e . " T h e r e f o r e , i t i s i m p o r t a n t t o i d e n t i f y and to s e p a r a t e those m e d i c a l s e r v i c e s t h a t are of v a l u e from those t h a t are of l i t t l e or no v a l u e . T h i s can be a c h i e v e d by c o n d u c t i n g proper e v a l u a t i o n s of a m e d i c a l t e c h n o l o g y b e f o r e i t i s adopted i n p r a c t i c e . To j u s t i f y the i n t r o -d u c t i o n of a new m e d i c a l t e c h n o l o g y , i d e a l l y i t needs to 1 be shown t h a t i t i s both c l i n i c a l l y and e c o n o m i c a l l y more e f f e c t i v e than e x i s t i n g ones. A m e d i c a l t e c h n o l o g y can be a s s e s s e d a t many l e v e l s . T h i s w i l l be d i s c u s s e d i n the next c h a p t e r . Such l e v e l s of assessment can be a p p l i e d to the e v a l u a t i o n of computed tomography (CT) s c a n n i n g . T h i s study w i l l f o c u s on one a s p e c t of the e f f e c t s of CT. The purpose of t h i s study i s to determine whether or not CT s c a n n i n g has an impact on the u t i l i z a t i o n of n e u r o - d i a g n o s t i c t e s t s by h o s p i t a l i s e d p a t i e n t s w i t h b r a i n tumour or c e r e b r o v a s c u l a r d i s e a s e . The CT scanner was developed by EMI i n Great B r i t a i n i n the l a t e 1960's. I t was q u i c k l y h a i l e d as the g r e a t e s t advance i n r a d i o l o g y s i n c e the i n t r o d u c t i o n of X-r a y s . The f i r s t CT head scanner to be used c l i n i c a l l y was i n s t a l l e d a t the A t k i n s o n M o r l e y ' s H o s p i t a l (U.K.) i n 3 1971. At f i r s t , CT was used f o r e x a m i n a t i o n s of the head. L a t e r , w i t h the development of body s c a n n e r s , CT was used i n e x a m i n a t i o n s of the abdomen and t h o r a x . The f i r s t body scanner was i n s t a l l e d at Georgetown U n i v e r s i t y M e d i c a l C e n t r e ( U . S . ) , and was c o m m e r c i a l l y marketed by 3 P f i z e r . CT s c a n n i n g combines r a d i o l o g i c a l and computer t e c h n i q u e s t o produce c r o s s - s e c t i o n a l p i c t u r e s of the head 2 or body. X-rays are passed through a c r o s s - s e c t i o n of the body and d e t e c t e d by s c i n t i l l a t i o n c o u n t e r on the o t h e r s i d e . The r e a d i n g s are r e c o r d e d by very s e n s i t i v e d e t e c t o r s and are then p r o c e s s e d by a computer to produce a c r o s s - s e c t i o n a l p i c t u r e . In c o n v e n t i o n a l X-ray p i c t u r e s , the i n t e r n a l s t r u c t u r e s are superimposed on each o t h e r . High d e n s i t y t i s s u e s , l i k e bone, tend to mask u n d e r l y i n g s t r u c t u r e s . T h i s i s a p a r t i c u l a r problem i n the s k u l l . In c o n v e n t i o n a l X-ray f i l m s , i t i s a l s o d i f f i c u l t t o d i s t i n g u i s h between a d j a c e n t s o f t t i s s u e s of s i m i l a r d e n s i t y , or to d i s t i n g u i s h between normal and d i s e a s e d t i s s u e s i n an organ where they are of s i m i l a r d e n s i t y . In comparison, CT s c a n n i n g p r o v i d e s a much h i g h e r degree of r e s o l u t i o n because of the s e n s i t i v i t y of the d e t e c t o r s and the l a r g e number of r e a d i n g s t a k e n . Over 300,000 4 i n d i v i d u a l r e a d i n g s are taken i n a t o t a l s c an. While t h e r e are a l a r g e number of a r t i c l e s on CT, most of these d e a l w i t h t e c h n i c a l c a p a b i l i t y and d i a g n o s t i c a c c u r a c y . Few a r t i c l e s e v a l u a t e CT i n terms of i t s impact on c o s t s or on o t h e r i n v e s t i g a t i o n s . F u r t h e r -more, the m a j o r i t y of these are about e x p e r i e n c e s i n the U n i t e d S t a t e s , and are u s u a l l y i n a t e r t i a r y s e t t i n g . I t i s hoped t h a t t h i s s tudy w i l l c o n t r i b u t e to knowledge of the e f f e c t i v e n e s s of CT by d e s c r i b i n g the e x p e r i e n c e i n a Canadian community h o s p i t a l . 3 The following chapters w i l l provide d e t a i l s about the study. The l i t e r a t u r e review i s contained in Chapters 2 and 3. Chapter 2 i s a general discussion on the a l l o c a t i o n of resources and the evaluation of medical technology. Chapter 3 discusses the results of previous evaluative studies on CT regarding i t s safety, e f f i c a c y , effectiveness, e f f i c i e n c y and a v a i l a b i l i t y . The method-ology section i s contained in Chapter 4. The results of this study are presented in Chapter 5. In Chapter 6, the results are discussed in the context of previously reported studies. Conclusions are drawn in l i g h t of these results . 4 CHAPTER 2 LITERATURE REVIEW: ALLOCATION OF RESOURCES AND EVALUATION OF MEDICAL TECHNOLOGY 2.1 INTRODUCTION The Office of Technology Assessment of the United States defined medical technology as "the drugs, devices, and medical and surgical procedures used in medical care, and the organizational and support systems 5 within which such care i s delivered." Since the 1930's, when the armamentarium of the physician was limited, there have been tremendous advances in medical technology. A n t i b i o t i c s , chemotherapy, lasers, transplantation, CT, nuclear magnetic imaging, and genetic engineering are just a few of the many examples. As a re s u l t , the practice of medicine today i s increasingly dependent on technology. Some of these technologies have undoubtedly contributed to the improvement in health status of the population. These include immunization against po l i o m y e l i t i s , diphtheria, pertussis, tetanus and various childhood v i r a l diseases, and the use of 5,6 a n t i b i o t i c s for ba c t e r i a l i n f e c t i o n s . In addition, many other technologies have at least enabled the r e l i e f of symptoms and have provided r e h a b i l i t a t i o n for many patients with diseases that cannot be successfully 5 p r e v e n t e d or c u r e d . Examples are p l e n t i f u l i n t h i s group, such as hormone replacement f o r e n d o c r i n e d e f i c i e n c i e s , the t r e a t m e n t of c o n g e s t i v e c a r d i a c f a i l u r e w i t h d i g o x i n , and the management of asthma w i t h b r o n c h o d i l a t o r s . However, one i m p o r t a n t p o i n t t o note i s t h a t some of the major t e c h n o l o g i c a l advances made i n the past two decades have been a s s o c i a t e d w i t h the p r o l o n g a t i o n of l i f e i n p a t i e n t s s u f f e r i n g from c h r o n i c i n c u r a b l e d i s e a s e s . Such improvements i n m e d i c a l t e c h n o l o g y have sometimes a c t u a l l y produced i n c r e a s i n g l e v e l s of d i s a b i l i t y because they enabled the s u r v i v a l of s e v e r e l y d i s a b l e d p e r s o n s . A t y p i c a l example i s the use of l i f e - s u p p o r t systems on p a t i e n t s w i t h s e v e r e and i r r e v e r s i b l e b r a i n damage. In t h i s c h a p t e r , we s h a l l l o o k a t the i s s u e of r e s o u r c e a l l o c a t i o n and the need f o r proper e v a l u a t i o n of m e d i c a l t e c h n o l o g i e s . Some g e n e r a l approaches to such e v a l u a t i o n s a re b r i e f l y d i s c u s s e d . 2 .2 RESOURCE ALLOCATION In the U n i t e d S t a t e s , d u r i n g the 1970's, h e a l t h c a r e e x p e n d i t u r e s i n c r e a s e d a t an average r a t e of 14.7% 7 per y e a r . A f t e r a d j u s t i n g f o r i n f l a t i o n , age-mix, and p o p u l a t i o n s i z e , per c a p i t a e x p e n d i t u r e on h e a l t h c a r e r o s e by 4.5% per y e a r . As a f r a c t i o n of GNP, h e a l t h c a r e ' s share has i n c r e a s e from 5.3% i n 1960 to 7.6% i n 1970, and 6 t o more than 9.4% i n 1980. I t i s e s t i m a t e d t h a t i n 1984, the U n i t e d S t a t e s has spent US $393 b i l l i o n , or 11% of 8 GNP, on h e a l t h c a r e . As shown by Table 2.1, h e a l t h e x p e n d i t u r e s i n Canada r o s e from 6.0% of GNP i n 1961 to 8.4% i n 1982. However, u n l i k e the U n i t e d S t a t e s where the r i s e was p e r s i s t e n t , i n Canada t h e r e was a p e r i o d of s t a b i l i t y between 1971 and 1981 when t h e r e was l i t t l e change i n h e a l t h c a r e e x p e n d i t u r e s as a percentage of GNP. Over t h i s p e r i o d , the U n i t e d S t a t e s data showed a r i s e from 7.7% to 9.6% w h i l e the Canadian data showed a mi n i m a l i n c r e a s e , from 7.5% t o 7.6%. T h i s p e r i o d of s t a b i l i t y was p r o b a b l y due to the c o m p l e t i o n of u n i v e r s a l m e d i c a l i n s u r a n c e i n 1971. The jump i n the 1982 f i g u r e i s p a r t l y due to the e f f e c t of a deep r e c e s s i o n i n the g e n e r a l economy on the 9 s i z e of the GNP. In both the U n i t e d S t a t e s and Canada, people are concerned about t h i s r i s e i n h e a l t h c a r e c o s t s . Because of the l a c k of a d i r e c t and e x p l i c i t r e l a t i o n s h i p between the i n c r e a s e i n h e a l t h c a r e c o s t s , the expanded use of m e d i c a l t e c h n o l o g i e s , and the improvement i n h e a l t h s t a t u s , q u e s t i o n s have been r a i s e d about the e f f i c i e n c y of the 9 h e a l t h c a r e d e l i v e r y system. Evans w r i t e s : " I t i s g e n e r a l l y a c c e p t e d t h a t f o r most people most of the time h e a l t h s t a t u s i s p r i m a r i l y 7 T a b l e 2.1: N a t i o n a l H e a l t h E x p e n d i t u r e of Canada, 1961-82 YEAR T o t a l H e a l t h E x p e n d i t u r e (C$000,OOO's) Perc e n t a g e of G N P T o t a l P o p u l a t i o n (OOO's) H e a l t h Exp-e n d i t u r e Per Perso n (C$) 1961 2,375.5 6.0 18,238.2 130.2 1966 3,837.5 6.2 20,014.9 191.7 1971 7,122.3 7.5 21,568.3 330.2 1972 7,790.2 7.4 21,821.0 357.0 1973 8,720.3 7.1 22,095.0 394.7 1974 10,247.5 7.0 22,446.3 456.5 1975 12,381.4 7.5 22,799.5 543.1 1976 14,158.7 7.4 22,992.6 615.8 1977 15,532.6 7.4 23,257.7 667.8 1978 17,085.7 7.4 23,481.1 727.6 1979 19,055.4 7.2 23,670.7 805.0 1980 22,162.8 7.5 23,963.3 924.9 1981 25,752.2 7.6 24,341.7 1,057.9 1982 30,058.9 8.4 24,603.2 1,221.7 Sour c e s : 1. H e a l t h I n f o r m a t i o n D i v i s i o n , P o l i c y , P l a n n i n g and I n f o r m a t i o n B ranch, H e a l t h and W e l f a r e Canada, Ottawa, 1984. 2. Canadian S t a t i s t i c a l Review, S t a t i s t i c s Canada, 1961 - 1982. 8 dependent on sanitation, diet, shelter, . . . the great h i s t o r i c a l improvements in mortality and morbidity, l i f e expectancy and health status, experienced in now-developed countries, appear to owe much more to improvements in these areas than to the progress of health care narrowly defined." Although the introduction of immunizations and treatments of various diseases, mainly since 1935, have played a s i g n i f i c a n t role in improving health status, the decline in mortality over the past hundred years was due largely to improvements in the quality of water and food, better 10,11 hygiene and reduced exposure to infectious diseases. Therefore, when we allocate resources to improve the health status of the people, we need to pay attention to these environmental factors instead of merely focusing on the provision of health services. Thus, the issue that should he c a r e f u l l y considered i s how can limited resources be allocated to produce optimal benefits to the public? At the aggregate l e v e l , there are two major questions concerning resource a l l o c a t i o n . F i r s t , should we put more resources into health care or into alternate uses such as education, i n d u s t r i a l and a g r i c u l t u r a l production, or national defence? Second, i f we do decide to put more resources into health care, how can such resources be distributed in a cost-effective manner? Investments i n a new technology may mean that funds w i l l be diverted away from 9 h o s p i t a l s , h e a l t h manpower, d i s e a s e p r e v e n t i o n , and h e a l t h e d u c a t i o n . A p a r t f r o m t h e p r o b l e m o f r e s o u r c e a l l o c a t i o n a t t h e a g g r e g a t e l e v e l , r a t i o n i n g a l s o o c c u r s a t t h e i n d i v i d u a l p a t i e n t l e v e l . Once i t i s a p p a r e n t t h a t t h o s e who a r e i n need o f a c e r t a i n p r o c e d u r e c a n n o t be a l l accommodated, t h e q u e s t i o n becomes one o f w h i c h p o t e n t i a l r e c i p i e n t s a r e g o i n g t o d e r i v e t h e g r e a t e s t b e n e f i t s . A good e x a m p l e i s t h e r a t i o n i n g o f r e n a l t r a n s p l a n t a t i o n a s 12 a r e s u l t o f t h e l i m i t e d a v a i l a b i l i t y o f d o n o r k i d n e y s . 2.3 E V A L U A T I O N OF M E D I C A L T E CHNOLOGY I n o r d e r t o a l l o c a t e o u r r e s o u r c e s w i s e l y , we need t o e v a l u a t e t h e b e n e f i t s and s h o r t c o m i n g s o f e a c h 13 a l t e r n a t i v e . W e i s s d e s c r i b e s e v a l u a t i o n as t h e e x a m i -n a t i o n and w e i g h i n g o f a phenomenon a g a i n s t some e x p l i c i t o r i m p l i c i t y a r d s t i c k . The p u r p o s e i s t o measure t h e e f f e c t s o f an i n t e r v e n t i o n a g a i n s t t h e o b j e c t i v e s i t i s s u p p o s e d t o a c h i e v e . As an i n c r e a s i n g number o f t e c h n o -l o g i c a l i n n o v a t i o n s a r e b e i n g d e v e l o p e d f o r h e a l t h c a r e and s u c h new t e c h n o l o g i e s a r e o f t e n e x p e n s i v e and c o m p l i c a t e d , t h e need f o r p r o p e r l y c o n d u c t e d e v a l u a t i v e s t u d i e s becomes v e r y i m p o r t a n t . From t h e r e s u l t s o f s u c h e v a l u a t i o n s , c l e a r g u i d e l i n e s r e g a r d i n g t h e c o n d i t i o n s u n d e r w h i c h t h e new t e c h n o l o g y i s a p p l i c a b l e s h o u l d be d e v e l o p e d . F u r t h e r m o r e , a t e c h n o l o g y must be a s s e s s e d n o t 10 o n l y f o r i t s c l i n i c a l u s e f u l n e s s , but a l s o f o r i t s e f f e c t s on the h e a l t h c a r e system as a whole. A u s e f u l model f o r the e v a l u a t i o n of the o v e r a l l b e n e f i t of a t e c h n o l o g y i n v o l v e s assessment a t d i f f e r e n t l e v e l s . These l e v e l s are s a f e t y , e f f i c a c y , e f f e c t i v e n e s s , e f f i c i e n c y and a v a i l a b i l i t y . I n f o r m a t i o n on each l e v e l comes from a v a r i e t y of so u r c e s such as de v e l o p m e n t a l e x p e r i m e n t a t i o n s , c l i n i c a l t r i a l s , f i e l d e x p e r i e n c e , f o r m a l consensus development, e v a l u a t i v e r e s e a r c h and e p i d e m i o l o g i c a l s t u d i e s . S a f e t y i s the b a s i c s t a r t i n g p o i n t i n e v a l u a t i n g a new t e c h n o l o g y . The O f f i c e of Technology Assessment 14 (OTA) of the U n i t e d S t a t e s d e f i n e s s a f e t y as "a jud g e -ment of the a c c e p t a b i l i t y of the r i s k s posed by the use of a t e c h n o l o g y . " B e f o r e p e r m i s s i o n i s g i v e n f o r the c l i n i c a l a p p l i c a t i o n of a new m e d i c a l t e c h n o l o g y , i n o r d e r t o ensure t h a t i t i s s a f e , r e g u l a t o r y b o d i e s u s u a l l y r e q u i r e t h a t c e r t a i n e x p e r i m e n t a t i o n s be c a r r i e d o u t . Such e x p e r i -m e n t a t i o n s may i n c l u d e b i o c h e m i c a l s t u d i e s , b a c t e r i a l a s s a y s , a n i m a l e x p e r i m e n t a t i o n and e v e n t u a l l y human e x p e r i m e n t a t i o n . S i n c e no t e c h n o l o g y i s c o m p l e t e l y harm-l e s s , a judgement based on ev i d e n c e generated by such t e s t s r e g a r d i n g the r i s k s and b e n e f i t s of the t e c h n o l o g y must he made b e f o r e d i s s e m i n a t i o n of the t e c h n o l o g y i s a l l o w e d . I t i s i n t e r e s t i n g t o note t h a t s u r g i c a l and o t h e r 11 p r o c e d u r e s t h a t depend p r i m a r i l y on the s k i l l and t e c h n i q u e of the p r o v i d e r are not s u b j e c t to such c o n t r o l s . In such c a s e s , the r e s p o n s i b i l i t y of assessment i s l e f t to the v a r i o u s p r o f e s s i o n a l b o d i e s . 14 OTA d e f i n e s e f f i c a c y as "the p r o b a b i l i t y of b e n e f i t from the use of a m e d i c a l t e c h n o l o g y " . To put i t more s i m p l y , e f f i c a c y t e l l s us whether or not the t e c h n o l o g y works under recommended c o n d i t i o n s , i . e . can i t work? E f f i c a c y i s u s u a l l y e x p r e s s e d i n terms of "the type and p r o b a b i l i t y of b e n e f i t , the m e d i c a l problem g i v i n g r i s e t o use of the t e c h n o l o g y , the p o p u l a t i o n a f f e c t e d , and the c o n d i t i o n of use under which the t e c h n o l o g y i s 14 a p p l i e d . " In the e v a l u a t i o n of e f f i c a c y , i t i s assumed t h a t the s u b j e c t s have been c o r r e c t l y diagnosed and t r e a t e d , and t h a t f u l l c o mpliance has o c c u r r e d . In a c t u a l c l i n i c a l p r a c t i c e , c o n d i t i o n s are u s u a l l y f a r from i d e a l . Sometimes p a t i e n t s are i n c o r r e c t l y diagnosed and/or i m p r o p e r l y t r e a t e d . In a d d i t i o n , f u l l c o m pliance w i t h the recommended c o n d i t i o n s cannot be assumed. For example, p h y s i c i a n s may use a t e c h n o l o g y beyond what e f f i c a c y s t u d i e s have proven, and p a t i e n t s ( e i t h e r c o n s c i o u s l y or s u b c o n s c i o u s l y ) may not adhere to the p r e s c r i b e d t r e a t m e n t s . Thus an e f f i c a c i o u s t e c h n o l o g y which works w e l l under i d e a l c o n d i t i o n s may t u r n out to be not very u s e f u l i n a c t u a l p r a c t i c e . C o n s e q u e n t l y , i n 12 e v a l u a t i n g a t e c h n o l o g y , i t i s n e c e s s a r y t o a s s e s s the impact of v a r i o u s e x t e r n a l f a c t o r s on i t s e f f i c a c y , and i t s degree of a c c e p t a n c e by people to whom i t i s o f f e r e d . T h i s form of e v a l u a t i o n i s the e v a l u a t i o n of e f f e c t i v e -15 ness. A f t e r q u e s t i o n s of s a f e t y , e f f i c a c y and e f f e c t i v e n e s s have been s a t i s f a c t o r i l y answered, and b e f o r e the i s s u e of a v a i l a b i l i t y i s c o n s i d e r e d , one must a s s e s s the economic impact of such a d e c i s i o n . One s h o u l d c a r e f u l l y c o n s i d e r the c o s t s of the new t e c h n o l o g y and whether such c o s t s are j u s t i f i e d i f measured a g a i n s t the b e n e f i t s l o s t by not b e i n g a b l e to purchase o t h e r t e c h n o l o g i e s or h e a l t h c a r e p r o c e d u r e s . In o t h e r words, one needs t o study the e f f i c i e n c y of the t e c h n o l o g y . E f f i c i e n c y can be d e f i n e d as the c o s t i n r e s o u r c e s of 16 a t t a i n i n g the b e n e f i t s produced by the t e c h n o l o g y . E v i d e n c e of e f f i c i e n c y comes from economic e v a l u a t i o n which i s the c o m p a r a t i v e a n a l y s i s of a l t e r n a t i v e c o u r s e s of a c t i o n i n terms of both t h e i r c o s t s and t h e i r 15 consequences. In economic e v a l u a t i o n , we are e s s e n t i a l l y c o n s i d e r i n g whether a h e a l t h procedure i s worth doing compared w i t h o t h e r t h i n g s we c o u l d do w i t h the same r e s o u r c e s . There are two main methods of economic e v a l u a t i o n i n the f i e l d of h e a l t h c a r e . These are c o s t -13 b e n e f i t a n a l y s i s and c o s t - e f f e c t i v e n e s s a n a l y s i s . A c o s t -b e n e f i t a n a l y s i s p l a c e s a v a l u e on a l l b e n e f i t s or s h o r t -comings d e r i v e d from p e r f o r m i n g a p r o c e d u r e . The r e s u l t i n g net b e n e f i t would i n d i c a t e whether the procedure s h o u l d be performed under the recommended c o n d i t i o n s . In c o s t -e f f e c t i v e n e s s a n a l y s i s , c o s t s are r e l a t e d to a s i n g l e common e f f e c t t h a t may d i f f e r i n magnitude between a l t e r -9,17,18 n a t i v e programs. Apart from th e s e two main methods of economic e v a l u a t i o n , t h e r e are o t h e r r e l a t e d methods such as c o s t - m i n i m i z a t i o n a n a l y s i s and c o s t - u t i l i t y 15 a n a l y s i s . E s s e n t i a l l y , c o s t - m i n i m i z a t i o n a n a l y s i s i s a d e r i v a t i v e of c o s t - e f f e c t i v e n e s s a n a l y s i s , and c o s t -u t i l i t y a n a l y s i s i s a d e r i v a t i v e of c o s t - b e n e f i t a n a l y s i s . I n economic e v a l u a t i o n , i t i s i m p o r t a n t t o i d e n t i f y c l e a r l y a t the b e g i n n i n g whose c o s t s and b e n e f i t s are b e i n g a s s e s s e d . M e d i c a l t e c h n o l o g y a f f e c t s p a t i e n t s , 9 h e a l t h p r o f e s s i o n a l s , governments and t a x p a y e r s . What i s c o s t t o one p a r t y may be b e n e f i t to a n o t h e r . For example, the performance of a m e d i c a l procedure may i n c r e a s e the c o s t t o whoever has to pay f o r i t , but i t i s c e r t a i n l y a b e n e f i t to the p r o v i d e r i n the form of income. I d e a l l y , i t s h o u l d a l s o be a b e n e f i t to the p a t i e n t i n the form of improved h e a l t h s t a t u s . The model of economic e v a l u a t i o n i s r e a s o n a b l y s t r a i g h t f o r w a r d , but i n p r a c t i c e i t i s a c t u a l l y v ery com-14 diagnostic procedures, one has to pay special attention to the selection of comparable patient groups, the i d e n t i f i c a t i o n of relevant diagnostic pathways, and the 17 measurement of diagnostic accuracy, costs and outcomes. In the assessment of costs, we need to i d e n t i f y and c l a r i f y two points. F i r s t , we should specify to whom such costs are applicable (patient, i n s t i t u t i o n , govern-ment or taxpayer). Second, we have to consider a l l components of costs. These include: 1. Capital costs, which consist of the cost of equipment and cost of the premises in which the equipment i s i n s t a l l e d . 2. Operating costs, which include labour, materials and 19 other overheads. In the case of CT, OTA estimates that 50 to 75% of the cost of CT scans of the head are attributable to operating and maintaining the scanner. 3. Spin-off costs, which are sometimes d i f f i c u l t to i d e n t i f y prospectively. By f a c i l i t a t i n g the perform-ance of a service at high volume, a technology may induce u t i l i z a t i o n . A good example i s automation in the c l i n i c a l laboratory that has resulted in 15 20 increased u t i l i z a t i o n . Another way spin-off costs can occur i s that a new technology can lead to higher costs by increasing the use of additional procedures which are themselves cost l y . For example, electronic f o e t a l monitoring per se i s not expensive, but i t s use has been associated with an increased rate of 21 Caesarean sections. Having worked through the dif f e r e n t l e v e l s of the evaluation of a medical technology concerning safety, e f f i c a c y , effectiveness and e f f i c i e n c y , the next l e v e l to be assessed i s the a v a i l a b i l i t y of the technology. In 15 other words, i s i t reaching those who need i t ? Epidemio-l o g i c a l data are important when analysing the a v a i l a b i l i t y 22 of a technology. We need to find out the following: How common are the conditions for which the technology i s used? What are the age d i s t r i b u t i o n s for these conditions? And what i s the overall contribution of the technology to the reduction of morbidity and mortality in the population 3 served? Apart from these factors of safety, e f f i c i a c y , effectiveness and e f f i c i e n c y , external influences also play a role in determining the a v a i l a b i l i t y of a medical technology. Such influences include s o c i a l and economic 2 p o l i c i e s as well as legal and e t h i c a l issues. 16 23 In a study by the Institute of Medicine in Washington, D.C, another model for the assessment of diagnostic technology based on the work of Fineberg, Bauman, and Sosman i s proposed. Five l e v e l s of assessment are involved. These are technical c a p a b i l i t y , diagnostic accuracy, diagnostic impact, therapeutic impact and pat-ient outcome. Technical c a p a b i l i t y refers to the type, amount, and quality of information the technology can provide, as well as the existence of possible hazards. Diagnostic accuracy i s the a b i l i t y of the technology to provide information that contributes toward a correct diagnosis. Diagnostic impact addresses the extent to which the technology replaces other diagnostic tests. Thera-peutic impact refers to the extent of subsequent changes in the management of the patient as a result of information provided by the technology. Patient outcome i s measured by patient morbidity and mortality as a result of exposure to the technology. Actually, the Fineberg model of technology assessment l i s t s the ways by which we could assess the issues of safety, e f f i c a c y and effectiveness. In essence, technical c a p a b i l i t y comprises the issue of safety, diagnostic accuracy i s an issue of e f f i c a c y , while diagnostic impact, therapeutic impact and patient outcome are issues of effectiveness. Compared to the f i r s t model which we have discussed, the Fineberg model has l e f t out 17 two' important elements. These are e f f i c i e n c y or economic impact and the issue of a v a i l a b i l i t y . However, the Fine-berg model does contain features that are appropriate to the assessment of a diagnostic technology. By combining these two models of evaluation, we can come up with a t h i r d model that can be applied to the assessment of CT. This "combined model" w i l l contain the following components: technical c a p a b i l i t y and safety, diagnostic accuracy, diagnostic impact, therapeutic impact, patient outcome, economic impact, and a v a i l -a b i l i t y . In the next chapter, we s h a l l review the results of relevant studies of CT of the head in terms of these components. 18 CHAPTER 3 LITERATURE REVIEW: EVALUATION OF COMPUTED TOMOGRAPHY 3.1 INTRODUCTION In 1978, the O f f i c e of Technology Assessment 19 (OTA) of the U n i t e d S t a t e s c o n c l u d e d i n i t s r e p o r t on CT, "1. W e l l designed s t u d i e s of e f f i c a c y of CT scanners were not conducted b e f o r e wide-spread d i f f u s i o n o c c u r r e d . I n f o r m a t i o n i s s t i l l i n c o m p l e t e on b e n e f i t s , i n d i v i d u a l s and p o p u l a t i o n s who can b e n e f i t , d i s e a s e t h a t can be d i a g n o s e d , and a p p r o p r i a t e con-d i t i o n s of use . . . 2. Those s t u d i e s t h a t had been done by mid-1977 showed t h a t CT head scanners perform r e l i -a b l y and p r o v i d e a c c u r a t e d i a g n o s e s of n e a r -l y a l l a b n o r m a l i t i e s i n or near the b r a i n f o r 80 t o 100 p e r c e n t of p a t i e n t s . . . 3. CT s c a n n i n g i s r e p l a c i n g o t h e r d i a g n o s t i c p r o c e d u r e s . I n p a r t i c u l a r , the use of CT head s c a n n i n g has reduced the use of pneumo-encephalography, and i n some s e t t i n g s , c e r e -b r a l a r t e r i o g r a p h y and r a d i o n u c l i d e b r a i n scan as w e l l . However, many more CT scans were be i n g performed than would be neces-s i t a t e d by s i m p l e replacement of o t h e r d i a g -n o s t i c p r o cedures . . . 4. L i t t l e i n f o r m a t i o n was a v a i l a b l e about the impact of CT s c a n n i n g on e i t h e r the p l a n n i n g of t h e r a p y or p a t i e n t h e a l t h . . . 5. The r i s k from CT head s c a n n i n g appears t o be lower than t h a t of the d i a g n o s t i c p r o c e d u r e s i t i s r e p l a c i n g , and the p a i n and d i s c o m f o r t are d e f i n i t e l y lower i n many c a s e s . " 19 Many e v a l u a t i v e s t u d i e s on CT have been c a r r i e d out s i n c e the OTA r e p o r t was r e l e a s e d , but the above remarks made by OTA are j u s t as v a l i d today as they were i n 1978. I n p a r t i c u l a r , most s t u d i e s showed t h a t more CT scans were done than would be expected i f o n l y s i m p l e r eplacement of o t h e r d i a g n o s t i c t e s t s took p l a c e . A l s o , t h e r e i s s t i l l l i t t l e i n f o r m a t i o n on the impact of CT on th e r a p y and p a t i e n t outcome. I n t h i s c h a p t e r , some of these s t u d i e s w i l l be d i s c u s s e d i n l i g h t of the "combined model" of e v a l u a t i o n proposed i n Chapter 2. 3 . 2 TECHNICAL CAPABIL ITY AND SAFETY OF COMPUTED TOMOGRAPHY I n the s h o r t p e r i o d s i n c e 1971 when CT was f i r s t 3 used c l i n i c a l l y , i t has become an i m p o r t a n t p a r t of m e d i c a l p r a c t i c e . CT i s now w e l l - a c c e p t e d by both p h y s i -c i a n s and p a t i e n t s . Over the r e l a t i v e l y s h o r t h i s t o r y of CT, a number of i n n o v a t i o n s have been made to enhance i t s c a p a b i l i t i e s . Such i n n o v a t i o n s have r e s u l t e d i n c l e a r e r images w i t h fewer a r t e f a c t s , t h e r e b y e x t e n d i n g the type and scope of the e x a m i n a t i o n s . CT s c a n n i n g i s t h e r e f o r e b e i n g a p p l i e d t o a w i d e n i n g range of c l i n i c a l problems. L e t us b r i e f l y examine some of the s e advances i n the f o l l o w i n g d i s c u s s i o n . When CT was f i r s t i n t r o d u c e d , scan t i m e s of more than f i v e minutes were r e q u i r e d . Today, scan times a re 20 l e s s than f i v e seconds. I n a d d i t i o n , many more r e a d i n g s are t a k e n d u r i n g t h i s f i v e - s e c o n d p e r i o d than one would do 24 over f i v e minutes w i t h the o r i g i n a l machines. T h i s marked s h o r t e n i n g of scan t i m e s a l l o w s c l e a r e r p i c t u r e s i n s i t u a t i o n s of u n c o o p e r a t i v e or s e r i o u s l y i l l p a t i e n t s who are u n w i l l i n g or unable to h o l d s t i l l or to suspend b r e a t h i n g f o r even a few seconds. The s h o r t s c a n n i n g time a l s o o b v i a t e s the need f o r bowel muscle r e l a x a n t s t o sto p p e r i s t a l s i s which f r e q u e n t l y caused a r t e f a c t s w i t h l o n g e r 4 s c a n n i n g t i m e . There a re now many s o f t w a r e programs f o r CT t h a t a l l o w f o r b e t t e r d i s p l a y of i t s images. For example, a b u i l t - i n "scanogram" can produce a f r o n t a l or l a t e r a l f u l l - t h i c k n e s s image s i m i l a r to a c o n v e n t i o n a l r a d i o -4 graph. There a re s o f t w a r e programs t h a t a re used i n the p l a n n i n g of r a d i o t h e r a p h y . These programs can a c c u r a t e l y l o c a t e a tumour i n r e l a t i o n t o the s k i n and a d j a c e n t organs. The p l a n n i n g of r a d i o t h e r a p y f i e l d s can, t h e r e -4 f o r e , become e x t r e m e l y a c c u r a t e . Some newer s o f t w a r e programs can p r o v i d e f o r c o l o u r d i s p l a y o p t i o n s and t h r e e -d i m e n s i o n a l image p r e s e n t a t i o n . The i n t r o d u c t i o n of c o l o u r d i s p l a y o p t i o n s w i l l be u s e f u l i n d e m o n s t r a t i n g d i f f e r e n t i n t e n s i t y i s o d o s e c o n t o u r s f o r r a d i o t h e r a p y 24 tr e a t m e n t p l a n n i n g . T h r e e - d i m e n s i o n a l CT image p r e -s e n t a t i o n w i l l improve d i a g n o s i s by e n a b l i n g p h y s i c i a n s t o 21 24 v i s u a l i z e body structures in a better perspective. This w i l l also be useful in pre-surgical assessment as i t w i l l enable a better perception of the lesion in r e l a t i o n to the organs of the body. The use of s p e c i a l l y designed intravenous con-trast materials has greatly improved the a b i l i t y of CT to i d e n t i f y lesions. This i s especially true in CT of the 25 abdomen. For example, an intravenous l i p i d - s o l u b l e con-trast material, ethiodised o i l emulsion, i s used to reveal lymphoma deposits in the l i v e r and spleen. Metastases of the order of 0.25 to 0.5 centimeter in diameter can be 4 visualized with this type of contrast agent. The use of intravenous contrast materials in conjunction with new software programs for faster scanners enables "angiotomo-graphy" to be performed. This technique i s useful in diseases such as aort i c dissections, aneurysms, vascular 4 stenoses, and vascular tumours. The use of intravenous 26 contrast materials i s now very common. Evens has analyzed data from ninety-four medical CT i n s t a l l a t i o n s and has found that contrast materials are used in approx-imately 70% of body and 80% of head examinations. Very l i t t l e has been written about the safety aspect of CT. This may simply r e f l e c t that CT i s a r e l a -t i v e l y safe procedure. However, there are at least two r i s k s , the r i s k of radiation exposure, and the r i s k of 22 adverse r e a c t i o n s t o the i n t r a v e n o u s i n j e c t i o n of c o n t r a s t m a t e r i a l s . The i n t r o d u c t i o n of new s c a n n e r s w i t h s h o r t e r s c a n n i n g times has s i g n i f i c a n t l y reduced r a d i a t i o n expo-s u r e . The dose of r a d i a t i o n r e c e i v e d d u r i n g s c a n n i n g i s r e l a t e d to the d e s i r e d a n a t o m i c a l and d e n s i t y r e s o l u t i o n , the number of s e c t i o n s o b t a i n e d , and the r e l a t i v e s p a c i n g of the s e c t i o n s . R a d i a t i o n exposure from the average CT e x a m i n a t i o n i s comparable t o a more c o n v e n t i o n a l procedure 27 such as barium enema. With the i n c r e a s i n g use of i n t r a v e n o u s c o n t r a s t m a t e r i a l s and the i n t r o d u c t i o n of new t y p e s of c o n t r a s t m a t e r i a l s , t h e r e i s a s m a l l but d e f i n i t e r i s k of adverse r e a c t i o n s e i t h e r to the c h e m i c a l i t s e l f or to the p r o -cedure of i n t r a v e n o u s a d m i n i s t r a t i o n . However, t h e r e are no data i n the c u r r e n t l i t e r a t u r e on t h i s s u b j e c t . When CT was f i r s t i n t r o d u c e d , i t was used i n the e x a m i n a t i o n of i n t r a c r a n i a l l e s i o n s , m a i n l y tumours and haematomas. As a r e s u l t of CT 1s improved t e c h n i c a l capa-b i l i t i e s , i t i s now b e i n g a p p l i e d to an expanding spectrum of c l i n i c a l problems. In e x a m i n a t i o n of the head, CT can d e t e c t c o r t i c a l a t r o p h y , aneurysms, v a s c u l a r anomalies and 26 t e m p o r a l bone l e s i o n s . I n the body, CT i s used to study l e s i o n s of the l i v e r , s p l e e n , k i d n e y s , p a n c r e a s , and s o f t 28 r e t r o p e r i t o n e a l t i s s u e s . CT i s a l s o u s e f u l i n exami-23 nation of the spinal canal especially in evaluating com-pression of the spinal cord and nerve roots produced by 4 disc protrusions and tumours. Such widening applications of CT have continued to influence i t s u t i l i z a t i o n and d i f f u s i o n . These issues w i l l be discussed l a t e r in this chapter. 3.3 DIFFUSION OF COMPUTED TOMOGRAPHY In this section, we s h a l l look at the a v a i l a b i -l i t y of CT scanners in both the United States and Canada. In the United States, where new technologies tend to be more readily accepted, the f i r s t commercial head scanner was i n s t a l l e d at the Mayo C l i n i c in 1973. Other hospitals throughout the country quickly followed. Because of concern with the cost and the appropriate supply and d i s t r i b u t i o n of t h i s expensive technology, in 1978 the National Health Planning Program set up standards 29 for the acquisition of CT scanners. These standards remained in effect, u n t i l the end of 1982 when they were removed because further advances in CT technology had made them out-dated. State health planning agencies were allowed to develop their own standards for review of certificate-of-need applications to purchase CT scanners. 24 F i g u r e 3.1: C u m u l a t i v e Number of CT Scanners I n s t a l l e d i n  the U n i t e d S t a t e s (1973-1980). 1500 1400 1300 1200 1100 N 1000 U 900 M 800 B 700 E 600 R 500 400 300 200 100 0 1973 74 75 76 77 YEAR 78 79 1980 Source: O f f i c e of Technology Assessment, 30 Congress of the U n i t e d S t a t e s . 25 19 I n i t s o r i g i n a l study done i n 1978, the O f f i c e of Technology Assessment (OTA) noted a r a p i d r a t e of d i f -f u s i o n of CT s c a n n e r s a c r o s s the U n i t e d S t a t e s . However, 30 i n a f o l l o w - u p study p u b l i s h e d by OTA i n 1981, i t was observed t h a t t h e r e was a s i g n i f i c a n t drop i n the r a t e d u r i n g 1978, 1979 and 1980. T h i s i s i l l u s t r a t e d by F i g u r e 3.1. In 1977, CT s c a n n e r s were i n s t a l l e d a t the r a t e of f o r t y per month. In 1978, the r a t e f e l l by h a l f . In 1979 and 1980, the r a t e of i n s t a l l a t i o n f e l l t o about seventeen s c a n n e r s per month. The d i s t r i b u t i o n of s c a n n e r s a c r o s s the U n i t e d S t a t e s i s shown i n T a b l e 3.1. I t can be observed t h a t t h e r e are s i g n i f i c a n t d i f f e r e n c e s between the v a r i o u s s t a t e s i n t h e i r s c a n n e r - t o - p o p u l a t i o n r a t i o s . T h i s i s p r o b a b l y the r e s u l t of a number of l o c a l f a c t o r s i n c l u d i n g p o p u l a t i o n d i s t r i b u t i o n , economic c o n d i t i o n s , t y p e s of h e a l t h i n s u r a n c e , a v a i l a b i l i t y of CT f a c i l i t i e s i n nearby s t a t e s , and the s t a t e ' s own g u i d e l i n e s f o r the purchase of CT s c a n n e r s . 31 In 1982, T e r h o r s t c a r r i e d out an e x t e n s i v e study by p e r f o r m i n g a n a t i o n a l survey of CT u n i t c a p a c i t y i n the U n i t e d S t a t e s . She r e p o r t e d t h a t t h e r e were a t o t a l of 2,019 scanners i n the U n i t e d S t a t e s . Comparing T e r h o r s t ' s f i g u r e and OTA's e s t i m a t e of 1471 s c a n n e r s i n 30 1980 , t h e r e appeared to have been a r e a c c e l e r a t i o n of 26 T a k l a S . l i D i a t r l b u t l o n o f CT S c a n n e r * i n t h e U n i t e d S t a t e s ( 1 9 8 0 ) . NUMBER OF SCANNERS RATIO OF SCANNERS PER MILLION POPULATION S T A T E NUMBER OF SCANNERS RATIO OF SCANNERS PER MILLION POPULATION S T A T E HOSPITAL O F F I C E S HOSPITAL O F F I C E S NEW ENGLAND SOUTH ATLANTIC M a i n e 5 0 4.6 D e l a w a r e 1 1 3.4 New H a a p a h l r e 3 1 4.7 Ma r y l a n d 21 6 6.5 V e r a o n t 1 1 4.6 D i s t r i c t o f N a a a a c h u a e t t a 25 5 5.2 C o l u m b i a 10 1 16.7 Rhode I a l a n d 2 1 3.3 V i r g i n i a 27 4 6.0 C o n n e c t i c u t 12 1 4.2 West V i r g i n i a 9 1 5.3 N o r t h C a r o l i n a 28 4 5.7 S o u t h C a r o l i n a 7 0 2.4 MIDDLE ATLANTIC G e o r g i a 32 7 7.6 F l o r i d a 70 27 10.9 Ne» T o r k 61 42 5.9 New J e r e e y 20 7 3.7 WEST SOUTH CENTRAL P e n n s y l v a n i a 66 7 6.2 A r k a n s a a 9 1 4.6 L o u l a i a n a 25 3 6.9 EAST NORTH CENTRAL O k l a h o a a 15 0 5.2 T e x a s 77 25 7.7 O h i o SO 12 5.8 I n d i a n a 24 6 5.5 MOUNTAIN I l l i n o i s 69 11 7.1 M i c h i g a n 27 6 3.6 M o n t a n a 3 0 3.8 W l a c o n a l n 20 6 5.5 I d a h o 3 0 3.3 W y o a l n g 2 0 4.4 C o l o r a d o 17 3 7.2 UBST NORTH CENTRAL New M e i l e o 5 5 8.0 A r l r o n a 18 4 9.0 H l n n e e o t a 17 6 5.7 U t a h 6 1 5.1 Iowa 13 4 5.9 Nevada 6 1 12.8 H l a a o u r l A* 2 9.4 N o r t h D a k o t a 5 1 9.1 P A C I F I C S o u t h D a k o t a 3 0 4.4 N e b r a a k a 11 2 8.3 W a s h i n g t o n 19 11 7.6 U n t i l IA 0 5.9 O r e g o n 16 0 6.3 C a l i f o r n i a 196 43 10. 5 A l a s k a 3 0 7.4 BAST SOUTH CENTRAL H a w a i i 5 0 5.5 I e n t u c k y 11 2 3.7 P u e r t o R i c o 2 3 1.6 T e o n e a a e e 24 3 6.2 A l e b a a a 22 0 5.8 TOTAL IN UNITED STATES 1193 278 6.7 M l e a i e s l p p l 10 1 5.8 30 S o u r c e : O f f i c e o f T e c h n o l o g y A s s e s s m e n t , C o n g r e s s o f t h e U n i t e d S t a t e a . the rate of scanner i n s t a l l a t i o n s between the years 1980 and 1982. This could have been due to widening a p p l i -cations of CT, especially i n r e l a t i o n to the body. Terhorst estimated that in 1978, 68% of the scanners were body scanners as compared to 80% in 1982. In 1978, 75% of scans were of the head and the rest were of the body. In 1982, the percentage of body scans had increased to 43%. As might be expected, i n s t a l l a t i o n of new scan-ners resulted in an increase in hospital CT examinations. During the period 1979 to 1982, the number of CT scan pro-cedures performed in acute-care hospitals in the United 29 States t r i p l e d from 194,000 to 600,000. In the State of C a l i f o r n i a , between the years 1977 and 1981, head scans increased by 96% while body scans increased by a dramatic 32 463%. This increase in u t i l i z a t i o n appears to be at rates higher than the acquisition rate of scanners. This i s probably due to increases in both the range of a p p l i -cations and in physician acceptance of the technology. 30 In 1980, OTA reported that in the United States there were 6.7 CT scanners per m i l l i o n population (Table 3.1). For the year 1984, assuming a t o t a l of 2,200 33 34 CT scanners and a population of 234.4 m i l l i o n , t h i s ratio would have increased to 9.4. This represents a 40% increase over four years. 28 In Canada, as a r e s u l t of the o r g a n i z a t i o n of the h e a l t h c a r e system, the d i f f u s i o n of CT s c a n n e r s has been l e s s r a p i d . H o s p i t a l and m e d i c a l c a r e i n Canada i s p r o v i d e d by a d e l i v e r y system composed of independent p r o -v i d e r s who are r e i m b u r s e d by a government h e a l t h i n s u r a n c e scheme. The h e a l t h c a r e system can be r e g a r d e d as e s s e n t -i a l l y a t r i p a r t i t e r e l a t i o n s h i p i n v o l v i n g the p a t i e n t as r e c e i v e r , the p h y s i c i a n as p r o v i d e r , and the government as payer. Most p h y s i c i a n s f u n c t i o n as p r i v a t e p r a c t i -t i o n e r s and are r e i m b u r s e d by the system on a f e e - f o r -s e r v i c e b a s i s . H o s p i t a l s are u s u a l l y owned by m u n i c i p a -l i t i e s . They f u n c t i o n i n d e p e n d e n t l y , but t h e i r budgets ( b o t h o p e r a t i n g budget and c a p i t a l budget) are m a i n l y from g r a n t s p r o v i d e d by the p r o v i n c i a l government. Through t h i s system, the p u b l i c has i n d i r e c t c o n t r o l over i n s t i t u t i o n a l budgets and f e e s c h e d u l e s . However, the assessment of m e d i c a l t e c h n o l o g i e s i s u s u a l l y l e f t to the h e a l t h p r o f e s -35 s i o n s and i n s t i t u t i o n s . Evans w r i t e s : "Remarkably l i t t l e a t t e n t i o n has been g i v e n at the government l e v e l to the e v a l u a t i o n of p a r t i -c u l a r forms of c a r e . The g e n e r a l p h i l o s o p h y seems to have been to r e l y on i n d i v i d u a l p h y s i c i a n s and h o s p i t a l s to c a r r y out the p r o c e s s of t e c h n o l o g y assessment." N e v e r t h e l e s s , the f u n d i n g mechanism has p r o v i d e d s i g n i f i c a n t c o n t r o l over the i n t r o d u c t i o n and d i f f u s i o n of 29 medical technologies in Canada. As a res u l t , medical tech-nologies have not spread as quickly as those in the United States. Table 3.2 shows the distribution, of CT scanners in Canada. It can be seen that, on a population basis, Canada has s i g n i f i c a n t l y fewer scanners than the United States. For the year 1984, the overall r a t i o of scanners per m i l l i o n population was 2.9 i n Canada compared with a ra t i o of 9.4 for the United States. It i s worth noting that Japan, with approximately half the population of the United States, has approximately the same number of CT 33 scanners. Since a l l three countries, Canada, the United States, and Japan, are considered to be advanced in the f i e l d of medical care, the existence of such large differences in scanner a v a i l a b i l i t y would be an intere s t i n g subject to study i n terms of the reasons for such differences and the impact on the health care systems. It i s also interesting to note that, as in the case of the United States, there i s considerable variation in the rat i o s of scanners per m i l l i o n population between the provinces i n Canada.. This i s probably due to regional factors such as population d i s t r i b u t i o n , economic conditions, and l o c a l government p o l i c i e s . 30 T a b l e 3.2: D i s t r i b u t i o n of CT Scanners i n Canada (1984) . P R O V I N C E POPULATION (thousands) NUMBER of CT SCANNERS RATIO OF SCANNERS PER MILLION POPULATION Newfoundland 578.9 1 1.7 P r i n c e Edward I s l a n d 125.0 1 8.0 Nova S c o t i a 868.1 2 2.3 New Brunswick 712.3 2 2.8 Quebec 6,540.1 12 1.8 O n t a r i o 8,916.8 29 3.3 M a n i t o b i a 1,054.4 2 1.9 Saskatchewan 1,003.3 2 2.0 A l b e r t a 2,349.1 9 3.8 B r i t i s h Columbia 2,863.2 13 4.5 Yukon 21.7 0 0 Northwest T e r r i t o r i e s 49.3 0 0 TOTAL IN CANADA 25,082.2 73 2.9 Sour c e s : 1. I n s t i t u t i o n a l S t a t i s t i c s S e c t i o n , H e a l t h D i v i s i o n , S t a t i s t i c s Canada, 1984. 2. C l a r k e , C.E. and H r y c i u k , M a r i l y n , ( e d s ) , Corpus Almanac and Canadian Source Book, 20th E d i t i o n , Volume I , O n t a r i o : Southam Communications L i m i t e d , 1985. 31 3.4 IMPACT OF COMPUTED TOMOGRAPHY ON NEUROLOGICAL TESTS The p r e s e n t study w i l l l o o k at the impact of CT on the u t i l i z a t i o n of n e u r o l o g i c a l t e s t s and i t s subse-quent e f f e c t on c o s t s . I n t h i s s e c t i o n , we s h a l l r e v i e w p r e v i o u s l i t e r a t u r e on t h i s t o p i c . In p a r t i c u l a r , we s h a l l l o o k a t the d i a g n o s t i c impact and economic impact of CT under d i f f e r e n t s i t u a t i o n s and s e t t i n g s . One of the e a r l i e s t e v a l u a t i o n s of the e f f e c t of CT on o t h e r n e u r o l o g i c a l t e s t s was done a t the Mayo C l i n i c where the f i r s t head scanner i n the U n i t e d S t a t e s was i n -36 s t a l l e d . Baker found t h a t over a p e r i o d of e i g h t e e n months (June 1973 to November 1974), w i t h the e x c e p t i o n of e l e c t r o e n c e p h a l o g r a p h y (EEG) which had no volume change, a l l o t h e r n e u r o l o g i c a l t e s t s decreased d r a m a t i c a l l y . C e r e b r a l angiography was the l e a s t a f f e c t e d and decreased by o n l y 20%, pneumoencephalography f e l l by 50%, and n u c l i d e b r a i n s c a n n i n g f e l l by 55%. One p o i n t t o note r e g a r d i n g the data i s t h a t t h e s e are aggregate i n s t i t u -t i o n a l f i g u r e s which c o u l d be a f f e c t e d by the number of p a t i e n t s seen a t the Mayo C l i n i c and the d i s e a s e - m i x of these p a t i e n t s . A c t u a l l y t h e r e was l i t t l e change i n the number of p a t i e n t s . Baker s t a t e d t h a t "the number of p a t i e n t s examined i n thes e y e a r s i n c r e a s e d by about 1.5%". However, t h e r e was no i n f o r m a t i o n r e g a r d i n g d i s e a s e - m i x . I t i s c o n c e i v a b l e t h a t the a v a i l a b i l i t y of CT might have 32 affected r e f e r r a l patterns and hence changing the disease-mix. In passing, H i l l e r has b r i e f l y commented on the diagnostic accuracy of CT. It was claimed that there was an error rate of 4 to 5 percent, of which approximately half were f a l s e - p o s t i t i v e s and half were false-negatives. However, there were no data or information to support this observation. The pattern of the impact of CT on the various neurological tests revealed by the Mayo C l i n i c study i s confirmed by a subsequent study carried out by Knaus, 37 Schroeder and Davis at the George Washington University Medical Center (GWUMC). They assessed the diagnostic impact of CT on the u t i l i z a t i o n of neurological procedures and the economic impact in terms of t o t a l hospital charges. This was a before-after comparison and data were collected for the f i s c a l year 1973, when CT was not available, and for the f i r s t two complete f i s c a l years of i t s use (1975 and 1976). On an aggregrate i n s t i t u t i o n a l basis, the GWUMC study found that there was no change in the frequency of EEG while nuclear brain scans f e l l 14.5%, cerebral angiograms f e l l 15.6% and pneumoencephalograms f e l l 80%. These results are f a i r l y comparable to those of the Mayo C l i n i c study except for the smaller decrease in nuclear brain scans. 33 The GWUMC study also found that the u t i l i z a t i o n of CT scanning had exceeded that of a l l other neuro-diagnostic procedures combined. Hospital b i l l i n g s for neuro-diagnostic tests increased fourfold from US$321,000 in 1973 to US$1,314,204 in 1976. In 1976, 74% of the to t a l charges for neuro-diagnostic tests were attributed to CT scans. However, in their calculations, the authors did not adjust for the increases over the study period of unit charges for the tests. If we make such an adjustment by applying the 1976 fee schedule of GWUMC onto the number of tests done in 1973, then the adjusted charges i n 1973 would be US$415,325. This i s a threefold increase between 1973 and 1976 rather than the fourfold increase when calculated from unadjusted charges. Nevertheless, this i s s t i l l a dramatic increase. As we sh a l l see l a t e r , the data collected in this thesis do not show such a large percentage increase. However, as pointed out before, the problem of looking at t o t a l i n s t i t u t i o n a l charges i s that such figures are affected by patient volume and disease-mix. Unlike the Mayo C l i n i c study which only considered aggregate i n s t i t u t i o n a l data, the GWUMC study has also examined the effect of CT on indi v i d u a l patient groups. Two groups of neurological patients were studied, one with cerebrovascular diseases and the other with brain 34 tumours. It was found that CT scanning had reduced the frequency of arteriography (p } 0.05) in the cerebro-vascular disease group and the frequency of EEGs (p } 0.001) and brain scans (p } 0.01) in the brain tumour group. 38 In 1977, Fineberg, Bauman and Sosman studied the effect of CT of the head on 194 patients who were scanned consecutively over a seventeen-day period at the Massachusetts General Hospital. Physicians who ordered CT were asked hypothetically what other neurological tests would be necessary i f CT were not available and how did the results of CT change the treatment of their patients. The results of this survey showed that CT had a major diagnostic impact as approximately 41% of nuclear scans, 52% of cerebral angiograms, and 73% of pneumoencephalo-grams were avoided. The estimated f a l l i n angiograms i s much larger than those reported by the Mayo C l i n i c study and by the GWUMC study. Since these figures were derived from what was e s s e n t i a l l y an opinion survey, they might not r e f l e c t what would have happened in actual practice. In their study, Fineberg, Bauman and Sosman have also looked at the therapeutic impact of CT; It was e s t i -mated that 19% of patients, who were exposed to CT, had a change in their therapy. Unfortunately, there were no detailed data on the effect of CT on patient outcome as a 35 r e s u l t of such changes i n t h e r a p y . . The a u t h o r s e x p l a i n e d t h a t because of the s m a l l number of p a t i e n t s i n v o l v e d (36 p a t i e n t s had t h e r a p y c h a n g e s ) , e s t i m a t e s i n p a t i e n t outcome might not be s t a t i s t i c a l l y m e a n i n g f u l . However, they p o i n t e d out t h a t i t was c l i n i c a l l y s i g n i f i c a n t t h a t t h e r a p y changes d i d improve outcome i n p a t i e n t s w i t h s u b d u r a l haematoma, but made no d i f f e r e n c e i n those w i t h i s c h a e m i c s t r o k e or i n t r a c e r e b r a l haemorrhage. The GWUMC study had shown a s i g n i f i c a n t i n c r e a s e i n t o t a l charges as a r e s u l t of CT. However, Enlow and 39 co-workers found q u i t e the o p p o s i t e . They s t u d i e d the e f f e c t of CT on the u t i l i z a t i o n and charges of a l t e r n a t i v e d i a g n o s t i c p r o c e d u r e s at the Barrow N e u r o l o g i c a l I n s t i t u t e of S t . Joseph's H o s p i t a l and M e d i c a l Center ( B N I ) . Monthly u t i l i z a t i o n d ata f o r EEG, n u c l e a r b r a i n s c a n s , pneumoencephalography and c e r e b r a l angiography were c o l l e c t e d over a t e n - y e a r p e r i o d (1969 to 1978). The CT scanner was i n t r o d u c e d i n 1975. There was no s i g n i f i c a n t change i n the p a t i e n t p o p u l a t i o n over the study p e r i o d . The d i a g n o s e s were head trauma ( 4 5 % ) , c e r e b r o v a s c u l a r d i s e a s e ( 4 1 % ) , m a l i g n a n t b r a i n tumours ( 7 % ) , and b r a i n a t r o p h y and a c q u i r e d h y d r o c e p h a l u s ( 7 % ) . Comparing the pre-CT p e r i o d w i t h the post-CT p e r i o d , EEGs, n u c l e a r b r a i n s c a n s , and pneumoencephalograms a l l d e c l i n e d s i g n i f i c a n t l y (24%, 58%, and 74% r e s p e c t i v e l y ) . However, i n c o n t r a s t to the s t u d i e s c i t e d so f a r , the average number of angiograms 36 was h i g h e r by 32% d u r i n g the post-CT p e r i o d . A l s o , i t i s worth n o t i n g t h a t , u n l i k e both the Mayo C l i n i c study and the GWUMC study which found no change i n the u t i l i z a t i o n of EEG, the BNI study showed t h a t EEG had d e c l i n e d by 24% over the study p e r i o d . In the BNI s t u d y , Enlow and co-workers have a l s o a s s e s s e d the economic impact of CT as a r e s u l t of i t s e f f e c t on the u t i l i z a t i o n of n e u r o l o g i c a l t e s t s . U s i n g r a t h e r c o m p l i c a t e d s t a t i s t i c a l t e c h n i q u e s , a t i m e - s e r i e s f o r e c a s t i n g model was s e t up to p r e d i c t the u t i l i z a t i o n of a l t e r n a t i v e n e u r o - d i a g n o s t i c t e s t s i f CT were not a v a i l a b l e . I t was p r o j e c t e d t h a t t h e r e would be a net i n c r e a s e i n the number of n e u r o l o g i c a l t e s t s due to i n c r e a s e s i n both n u c l e a r b r a i n scans and c e r e b r a l angiograms, even though these would be p a r t l y o f f - s e t by d e c r e a s e s i n EEG's and pneumoencephalograms. As a r e s u l t of CT, the r e d u c t i o n i n the u t i l i z a t i o n of a l t e r n a t i v e t e s t s had r e s u l t e d i n c o s t - s a v i n g s i n the second and t h i r d y e a r s of the post-CT p e r i o d . S i m i l a r to the f i n d i n g s of the BNI s t u d y , Newton 40 and co-workers have a l s o found c o s t - s a v i n g s f o l l o w i n g the i n c r e a s e d u t i l i z a t i o n of CT at the U n i v e r s i t y of C a l i -f o r n i a , San F r a n c i s c o (UCSF). The m e d i c a l and f i n a n c i a l r e c o r d s of t h r e e c o h o r t s (1976, 1978 and 1980), of twenty c o n s e c u t i v e p a t i e n t s each, were a s s e s s e d . These p a t i e n t s 37 had a l l undergone t r a n s p h e n o i d a l s u r g e r y f o r p i t u i t a r y adenomas. The average charge f o r r a d i o l o g i c a l t e s t s per p a t i e n t , a d j u s t e d to 1980 d o l l a r s , d ecreased from US$1,747 i n 1976 to US$585 i n 1980. T h i s was m a i n l y due to the d r a m a t i c d i s a p p e a r a n c e of both pneumoencephalography (from one per p a t i e n t i n 1976 to z e r o i n 1980) and a r t e r i o g r a p h y (from 0.85 per p a t i e n t i n 1976 to z e r o i n 1980). On the o t h e r hand, CT rose from 0.1 per p a t i e n t i n 1976 to one per p a t i e n t i n 1980. I t was a l s o found t h a t the average l e n g t h of h o s p i t a l s t a y had f a l l e n from 14.9 days i n 1976 to 8.1 days i n 1980. T h i s was m a i n l y due to a decrease i n p r e -o p e r a t i v e s t a y from 6.8 days i n 1976 to 1.9 days i n 1980. T h i s was a very s i g n i f i c a n t drop but the a u t h o r s d i d not e x p l a i n why i t had o c c u r r e d . Presumably, t h i s was p a r t l y due t o the c e s s a t i o n of the use of pneumoencephalography and a r t e r i o g r a p h y as p r e - o p e r a t i v e e v a l u a t i o n s , and the p o s s i b l e use of CT i n p r e - a d m i s s i o n t e s t i n g . However, t h e r e might be o t h e r reasons to account f o r t h i s s i z a b l e d ecrease i n p r e - o p e r a t i v e s t a y such as the i n c r e a s i n g p o p u l a r i t y of p r e - a d m i s s i o n t e s t i n g and t i g h t e r c o n t r o l of the l e n g t h of h o s p i t a l s t a y . No s i g n i f i c a n t changes i n the average l e n g t h of h o s p i t a l s t a y were observed i n a study by L a r s o n and 41 Omenn of the U n i v e r s i t y of Washington. They s t u d i e d the 38 diagnostic, therapeutic and economic impact of CT on the care of patients with suspected brain tumour at time of admission. Three groups of patients were analyzed, a before-CT group (1973/4), and two after-CT groups (1974/5 and 1975/6). Comparing the before-CT group with the l a t t e r after-CT group, a l l other neuro-diagnostic tests f e l l , EEG by 10%, arteriograms by 23%, nuclear brain scans by 54% and pneumoencephalograms by 75%. Although CT accounted for about 40% of the charges for rieuro-diagnostic tests in the after-CT groups, the t o t a l charges for neuro-diagnostic tests per patient (adjusted to the 1976 fee schedule) did not change. In their assessment of the therapeutic impact of CT, Larson and Omenn considered the speed of diagnostic work-up, the types of therapy and the length of hospital stay. The speed of diagnostic work-up was measured by the number of days required by the physician to make a d e f i n i t i v e diagnosis that agreed with the eventual discharge diagnosis. The types of therapy . were divided into medical, surgical and radiotherapy. They found l i t t l e change between the before-CT and the after-CT groups. In another study of the therapeutic impact of CT on neurological patients, Sterman and Schaumburg found that CT had resulted in altered therapy in 15% of the 39 patients. The difference i n the findings between these two studies might be due to the fact that.the Larson and Omenn study looked at brain tumour patients only while the Sterman and Schaumberg study looked at neurological patients in general (brain tumour patients accounted for less than ten percent). Summarizing these findings, i t appears that CT has had a major diagnostic impact on the u t i l i z a t i o n of neuro-diagnostic tests. A l l the studies reviewed in this section found that the introduction of CT was followed by a major f a l l in the u t i l i z a t i o n of pneumoencephalography and nuclear scanning. CT was c l e a r l y acting as a replace-ment for these tests. However, the effect of CT on EEG was r e l a t i v e l y 36 37 minor. The Mayo C l i n i c and the GWUMC studies found l i t t l e change in the overall u t i l i z a t i o n of EEG while the 39 41 BNI and the University of Washington studies found a small decrease. This i s not surprising as EEG i s ess e n t i a l l y a physiological test ( i . e . i t i s a test of nerve c e l l a c t i v i t y ) compared to CT which i s an anatomical test ( i . e . i t locates a l e s i o n ) . Thus i n some situations, CT i s not a substitute for EEG. For example, in the investigation of a cerebrovascular disease patient, the physician uses EEG to provide information on the state of a c t i v i t y of the brain c e l l s and to exclude 40 the p o s s i b i l i t y of e p i l e p s y . However, the s i t u a t i o n i s q u i t e d i f f e r e n t i f the o b j e c t i v e i s to l o c a t e a l e s i o n , such as i n a p a t i e n t w i t h a p o s s i b l e b r a i n tumour. In t h i s c a s e , CT i s much more u s e f u l than EEG i n d e f i n i n g the l o c a t i o n and the s i z e of the tumour. I n the case of c e r e b r a l a n g i o g r a p h y , most 36-38, 40-42 s t u d i e s r e p o r t e d m i l d to moderate d e c r e a s e s i n 39 i t s u t i l i z a t i o n , whereas the BNI study r e p o r t e d a 32% i n c r e a s e . T h i s i s p r o b a b l y due to the f a c t t h a t most of the d i a g n o s e s i n the BNI study were v a s c u l a r - r e l a t e d . The most f r e q u e n t d i a g n o s e s were head trauma (45%) and c e r e b r o v a s c u l a r d i s e a s e ( 4 1 % ) . These two d i a g n o s t i c c a t e g o r i e s would f r e q u e n t l y r e q u i r e the use of angiography t o a s s e s s the s t a t e of v a s c u l a r s u p p l y and the p o s s i b i l i t y of haemorrhage. As f o r the economic impact of CT on the t o t a l c o s t of n e u r o l o g i c a l t e s t s , the f i n d i n g s r e q u i r e c a r e f u l 40 i n t e r p r e t a t i o n . On a p a t i e n t group b a s i s , the UCSF study r e p o r t e d a s i g n i f i c a n t d ecrease i n c o s t s , w h i l e the 41 U n i v e r s i t y of Washington study r e p o r t e d no change. T h i s apparent d i s c r e p a n c y i n t h e i r f i n d i n g s c o u l d be due t o the f a c t t h a t the p a t i e n t groups i n these s t u d i e s were not e x a c t l y comparable. The UCSF study a s s e s s e d p a t i e n t s who were h o s p i t a l i z e d f o r t r a n s p h e n o i d a l s u r g e r y f o r p i t u i t a r y adenoma. The U n i v e r s i t y of Washington study a s s e s s e d 41 p a t i e n t s who were h o s p i t a l i z e d because they were s u s p e c t e d to have a b r a i n tumour. The UCSF p a t i e n t s were a d m i t t e d f o r d e f i n i t i v e t r e a t m e n t whereas the U n i v e r s i t y of Wash-i n g t o n p a t i e n t s were a d m i t t e d f o r i n v e s t i g a t i o n . Thus, one would expect the l a t t e r group of p a t i e n t s to r e q u i r e a wider s e l e c t i o n of t e s t s d u r i n g h o s p i t a l i z a t i o n . I n a d d i t i o n , the UCSF study r e p o r t e d t h a t p r e - o p e r a t i v e s t a y f e l l from 6.8 days i n the pre-CT p e r i o d to 1.9 days i n the post-CT p e r i o d . T h i s d r a m a t i c f a l l i n p r e - o p e r a t i v e s t a y i n the post-CT p e r i o d p r o b a b l y meant t h a t those p a t i e n t s might have had some of the n e u r o l o g i c a l t e s t s done b e f o r e a d m i s s i o n to h o s p i t a l . C o n s e q u e n t l y , the number of t e s t s d u r i n g h o s p i t a l i z a t i o n would f a l l . T h i s would account f o r the decrease i n the c o s t of n e u r o l o g i c a l t e s t i n g d u r i n g h o s p i t a l i z a t i o n i n the post-CT p e r i o d . On an aggregate i n s t i t u t i o n a l b a s i s , the GWUMC 37 study found a l a r g e i n c r e a s e i n the t o t a l c o s t of n e u r o l o g i c a l t e s t s i n the post-CT p e r i o d . T h i s was a t t r i b u t e d to the i n c r e a s e d use of CT. However, the BNI 39 study suggested t h a t , i f CT were not a v a i l a b l e , t h i s i n c r e a s e i n t o t a l c o s t would have been even h i g h e r . R e g arding the i s s u e of the t h e r a p e u t i c impact of 38 CT, both the M a s s a c h u s e t t s G e n e r a l H o s p i t a l study and 42 the Sterman and Schaumberg study showed a change i n t h e r a p y , as a r e s u l t of exposure to CT s c a n n i n g , i n 19% 42 and 15% of patients respectively. Such changes in therapy would be important i f a positive impact on the outcome of these patients could be demostrated. Unfortunately, these studies did not evaluate patient outcome. The UCSF '40 study reported a s i g n i f i c a n t decrease in the length of hospital stay. Normally, the length of hospital stay could be regarded as a measure of patient outcome. But in the UCSF study, the decrease was largely due to a shortening of pre-operative stay. This ce r t a i n l y could not be attributed to therapeutic changes subsequent to CT, as a l l patients (in both pre-CT and p'ost-CT periods) under-went the same therapy of transphenoidal surgery. The 41 University of Washington study reported that CT did not affect the speed of diagnostic work-up, patient therapy or the length of hospital stay. The difference in findings between this study and the other studies i s probably due to differences i n patient group composition because the results obtained in these studies were dependent upon the types of patients involved. For example, we would expect CT to have a bigger replacement effect on cerebral angio-graphy in brain tumour patients than in cerebro-vascular disease patients, since in the l a t t e r group i t i s often necessary to delineate cerebral blood supply. Therefore, when discussing the impact of CT, we should specify the diagnostic groups on which the findings are based. 43 None of t h e s e s t u d i e s e v a l u a t e d p a t i e n t outcome subsequent to t h e r a p y changes. P a t i e n t outcome may be de-f i n e d as the d i f f e r e n c e between i n i t i a l and f i n a l l e v e l s 43 of h e a l t h . There are s e v e r a l problems i n the e v a l u a t i o n of p a t i e n t outcome. F i r s t , we need to s p e c i f y c l e a r l y what t y p e s of p a t i e n t outcome we are i n t e r e s t e d i n and how to measure them. T h i s i s not easy because outcome i s not a f i n a l but r a t h e r an i n t e r m e d i a r y r e s u l t . Second, we need to s t a r t w i t h a l a r g e p a t i e n t sample because o n l y a s m a l l p o r t i o n of t h e s e p a t i e n t s w i l l e x p e r i e n c e t h e r a p y 38,42 changes as a r e s u l t of exposure to CT. Out of t h i s s m a l l p o r t i o n , p r o b a b l y not many w i l l have outcome 41 changes. Thus, i n o r d e r to d e t e c t outcome changes t h a t are of c l i n i c a l i m p o r t a n c e , a l a r g e sample of p a t i e n t s i s r e q u i r e d . I f one wishes t o prove s t a t i s t i c a l s i g n i f i c a n c e , an even l a r g e r sample might be n e c e s s a r y . T h i r d , the measurement of outcome changes may r e q u i r e a p r o l o n g e d p e r i o d of f o l l o w - u p i n o r d e r to a s s e s s the l o n g - t e r m e f f e c t of an i n t e r v e n t i o n . T h i s i s o f t e n c o s t l y and i m p r a c t i c a l . D e s p i t e these d i f f i c u l t i e s i n a s s e s s i n g p a t i e n t outcome, s t u d i e s i n t h i s f i e l d s h o u l d be encouraged because p a t i e n t outcome i s the u l t i m a t e measure of the e f f e c t i v e n e s s of an i n t e r v e n t i o n . P o l i c y d e c i s i o n s s h o u l d be based on the f i n d i n g s of such s t u d i e s . 44 Most of the s t u d i e s reviewed i n t h i s s e c t i o n have a s s e s s e d the impact of CT e i t h e r on an aggregate i n s t i t u t i o n a l b a s i s or on an i n d i v i d u a l p a t i e n t group 37 b a s i s . The GWUMC study was the o n l y one t h a t l o o k e d a t both a s p e c t s . Both types of f i n d i n g s are of p r a c t i c a l i m p o r t a n c e . In g e n e r a l , the a d m i n i s t r a t i o n ( h o s p i t a l or government) i s more i n t e r e s t e d i n f i n d i n g s based on aggregate i n s t i t u t i o n a l d a ta because t h i s w i l l i n f l u e n c e r e s o u r c e a l l o c a t i o n and the p l a n n i n g of f a c i l i t i e s and manpower. On the o t h e r hand, p h y s i c i a n s are l i k e l y t o be more i n t e r e s t e d i n f i n d i n g s based on p a t i e n t group data because these f i n d i n g s p r o v i d e i n f o r m a i o n on the e f f i c a c y or e f f e c t i v e n e s s of a c e r t a i n i n t e r v e n t i o n . In the p r e s e n t s t u d y , we are goi n g t o determine the impact of CT on the u t i l i z a t i o n of n e u r o - d i a g n o s t i c t e s t s . We s h a l l l o o k s p e c i f i c a l l y a t two d i a g n o s t i c groups: the b r a i n tumour group and the c e r e b r o v a s c u l a r d i s e a s e group. Based on the r e s u l t s of s t u d i e s r e viewed i n t h i s c h a p t e r , we expect to f i n d t h a t CT would have a major replacement e f f e c t on pneumoencephalography and n u c l e a r b r a i n s c a n n i n g . To a l e s s o r e x t e n t , CT would p r o b a b l y decrease the u t i l i z a t i o n of EEG and s k u l l r a d i o -graphy. However, the magnitude of such changes would d i f f e r between th e s e two d i a g n o s t i c groups. In the case of c e r e b r a l a n g i o g r a p h y , i t i s l i k e l y f o r CT to decrease i t s u t i l i z a t i o n i n the b r a i n tumour group. However, the 45 e f f e c t i s u n c e r t a i n i n the c e r e b r o v a s c u l a r d i s e a s e group because angiography i s f r e q u e n t l y e s s e n t i a l i n the i n v e s t i g a t i o n of these p a t i e n t s . At the aggregate i n s t i t u t i o n a l l e v e l , we p r o -b a b l y would see s i m i l a r t r e n d s . However, such t r e n d s might not be as o b v i o u s because th e s e d a t a are summations of a c t i v i t i e s of a l l p a t i e n t groups t r e a t e d a t the h o s p i t a l . N e v e r t h e l e s s , we would expect to f i n d a r a p i d i n c r e a s e i n CT scans i n the post-CT y e a r s . 46 CHAPTER 4 METHODOLOGY 4 . 1 INTRODUCTION T h i s s t u d y i s c a r r i e d out to d e t e r m i n e whether or not the i n t r o d u c t i o n of CT s c a n n i n g of the head a t a C a n a d i a n community h o s p i t a l has had any i m p a c t on the u t i l i z a t i o n of o t h e r n e u r o - d i a g n o s t i c t e s t s . I t i s m o d e l l e d on the s t udy c a r r i e d out by K n a u s , S c h r o e d e r and 37 D a v i s a t the George Wash ing ton U n i v e r s i t y M e d i c a l C e n t e r (GWUMC). The a im i s to see whether the f i n d i n g s of the GWUMC s tudy a r e r e p r o d u c i b l e i n a C a n a d i a n s e t t i n g . 4 . 2 SETTING T h i s s t u d y was c a r r i e d out a t the L i o n s Gate H o s p i t a l ( L G H ) , N o r t h V a n c o u v e r , B r i t i s h C o l u m b i a . LGH i s a community h o s p i t a l w i t h a p p r o x i m a t e l y f o u r hundred a c u t e - c a r e beds s e r v i n g the commun i t i e s of the N o r t h S h o r e . These c o m m u n i t i e s c o n s i s t of the D i s t r i c t of N o r t h V a n c o u v e r , the C i t y o f N o r t h V a n c o u v e r , the D i s t r i c t o f West V a n c o u v e r , the V i l l a g e of L i o n s B a y , and the R u r a l D i s t r i c t of Bowen I s l a n d . LGH i s the o n l y a c u t e - c a r e h o s p i t a l on the N o r t h S h o r e . The N o r t h Shore i s s e p a r a t e d from the r e s t of G r e a t e r Vancouver by an i n l e t , a c r o s s w h i c h t h e r e a re two b r i d g e s l i n k i n g t r a f f i c . As the N o r t h 47 Shore i s g e o g r a p h i c a l l y i n c l o s e p r o x i m i t y to the r e s t of G r e a t e r Vancouver, t h e r e i s a c o n s i d e r a b l e amount of c r o s s - f l o w of p a t i e n t s between the N o r t h Shore and the o t h e r p a r t s of G r e a t e r Vancouver. I t has been e s t i m a t e d t h a t a p p r o x i m a t e l y 80% of h o s p i t a l days at LGH are a t t r i b u t a b l e to r e s i d e n t s of the N o r t h Shore, and 80% of h o s p i t a l days of N o r t h Shore r e s i d e n t s are spent a t the 44 h o s p t i a l . The s i z e of the p o p u l a t i o n of the N o r t h Shore has remained r a t h e r s t a b l e over the past decade. A c c o r d i n g to the 1981 N a t i o n a l Census, t h e r e were 138,960 people l i v i n g i n the r e g i o n . Over the p e r i o d 1973 to 1981, t h e r e 44 was v i r t u a l l y no change i n the s i z e of the p o p u l a t i o n . 4 .3 STUDY DESIGN T h i s study i s a r e t r o s p e c t i v e , b e f o r e - a f t e r comparison of the u t i l i z a t i o n of n e u r o - d i a g n o s t i c t e s t s a t LGH. I t compares the u t i l i z a t i o n of t h e s e t e s t s b e f o r e and a f t e r the a v a i l a b i l i t y of CT. B e f o r e LGH i n s t a l l e d i t s own CT scanner i n 1982, some p a t i e n t s were sent to o t h e r h o s p i t a l s f o r CT s c a n -n i n g . Thus, the a f t e r - C T group a c t u a l l y c o n s i s t s of two t r a n s f e r - C T groups and one in-house-CT group. F i g u r e 4.1 i s a s c h e m a t i c r e p r e s e n t a t i o n of the study d e s i g n . 48 F i g u r e 4.1: Study Design Before-CT Group (1973) T r a n s f e r - C T Groups (1977 and 1981/2) In-House CT Group (1983/4) COMPARISON OF UTILIZATION OF NEURO-DIAGNOSTIC TESTS BETWEEN THESE GROUPS 4.4 STUDY PERIODS The f i r s t CT scanner i n the G r e a t e r Vancouver R e g i o n a l H o s p i t a l D i s t r i c t (which i n c l u d e s the N o r t h Shore) was i n s t a l l e d a t the Vancouver G e n e r a l H o s p i t a l i n 1974. The second was i n s t a l l e d a t the R o y a l Columbian H o s p i t a l i n May, 1980. L i o n s Gate H o s p i t a l o b t a i n e d i t s scanner i n Oct o b e r , 1982. B e f o r e t h a t t i m e , those i n p a t -i e n t s of LGH who r e q u i r e d CT were taken t o the Vancouver G e n e r a l H o s p i t a l ( b e f o r e mid-1980), or to the R o y a l Columbian H o s p i t a l ( a f t e r mid-1980) f o r t h e i r s c a n s . T h i s study i n v o l v e s f o u r 12-month p e r i o d s as shown i n Table 4.1. Because of the c o n s i d e r a b l e time s e p a r a t i o n between the before-CT p e r i o d and the i n - h o u s e , a f t e r - C T p e r i o d , two t r a n s f e r - C T p e r i o d s were i n c l u d e d i n the study t o g i v e a b e t t e r i n d i c a t i o n of the time t r e n d of e v e n t s . 49 Table 4.1: Study P e r i o d s PERIOD NATURE REMARK 1973 1977 1981/2* 1983/4* B e f o r e CT T r a n s f e r CT T r a n s f e r CT A f t e r CT No scanner a v a i l a b l e To Vancouver G e n e r a l H o s p i t a l To R o y a l Columbian H o s p i t a l In-house scanner a v a i l a b l e * There was a change i n the r e p o r t i n g of h o s p i t a l s t a t i s t i c s from c a l e n d a r year t o f i s c a l y e a r . 4.5 STUDY POPULATION Two groups of n e u r o l o g i c a l p a t i e n t s who were h o s p i t a l i z e d a t LGH d u r i n g the a b o v e - s t a t e d study p e r i o d s were i n c l u d e d i n t h i s s t u d y . These were the b r a i n tumour group and the c e r e b r o v a s c u l a r d i s e a s e group. The b r a i n tumour group i n c l u d e d ICD-9 codes 191, 198 and 225, and the c e r e b r o v a s c u l a r d i s e a s e group i n c l u d e d ICD-9 codes 430 to 438 ( a l l sub-codes were i n c l u d e d ) . For the f i r s t two study p e r i o d s (1973 and 1977), ICD-8 was i n use. However, t h e r e was l i t t l e d i f f e r e n c e between these two ICD c l a s s i f -i c a t i o n s i n r e l a t i o n t o the above d i a g n o s t i c groups. Ta b l e 4.2 shows the dia g n o s e s which c o r r e s p o n d t o these ICD-9 codes. 50 T a b l e 4 . 2 : S tudy Groups ICD-9 CODE DIAGNOSIS BRAIN TUMOUR GROUP 191 M a l i g n a n t neoplasm of b r a i n 198 Secondary neoplasm of b r a i n 225 B e n i g n neoplasm of b r a i n and o t h e r p a r t s of ne rvous sys tem CEREBROVASCULAR DISEASE GROUP 430 S u b a r a c h n o i d haemorrhage 431 I n t r a c e r e b r a l haemorrhage 432 S u b d u r a l haemorrhage 433 O c c l u s i o n or s t e n o s i s of p r e -c e r e b r a l a r t e r y 434 O c c l u s i o n o f c e r e b r a l a r t e r y 435 T r a n s i e n t i s c h a e m i c a t t a c k 436 A c u t e c e r e b r o v a s c u l a r d i s e a s e not o t h e r w i s e s p e c i f i e d 437 Other c e r e b r o v a s c u l a r d i s e a s e 438 L a t e e f f e c t of c e r e b r o v a s c u l a r d i s e a s e 51 These two d i a g n o s t i c groups were chosen f o r two re a s o n s . F i r s t , as p o i n t e d out i n S e c t i o n 4.1, t h i s study 37 i s m o delled on the GWUMC s t u d y , thus i n o r d e r t o make r e s u l t s comparable, the same d i a g n o s t i c groups are a s s e s s e d . Second, these two groups are exposed t o CT of the head more o f t e n than o t h e r d i a g n o s t i c groups. There-f o r e , i t i s a n t i c i p a t e d t h a t CT would have i t s g r e a t e s t d i a g n o s t i c impact on them. As i n the case of the GWUMC s t u d y , data on the b r a i n tumour and the c e r e b r o v a s c u l a r d i s e a s e groups w i l l be a n a l y z e d s e p a r a t e l y . These two groups of d i s e a s e s are d i f f e r e n t w i t h r e s p e c t t o p r e s e n t a t i o n , c l i n i c a l c o u r s e , method of i n v e s t i g a t i o n , t r e a t m e n t and p r o g n o s i s . Conse-q u e n t l y , the impact of CT on the u t i l i z a t i o n of n e u r o l o g i c a l t e s t s by these two d i a g n o s t i c groups might be expected to be d i f f e r e n t i n n a t u r e or i n degree. As the r e s u l t s w i l l show l a t e r , t h i s i s indeed the c a s e . For a p a t i e n t - a d m i s s i o n to be i n c l u d e d i n the st u d y , two c r i t e r i a must be met. F i r s t , the p r i m a r y d i a g -n o s i s ( i . e . the main reason f o r h o s p i t a l i z a t i o n ) must be one of those d i s e a s e s l i s t e d i n Table 4.2. Second, i t must be a f i r s t a d m i s s i o n , as the i n v e s t i g a t o r y p a t t e r n f o r r e - a d m i s s i o n cases i s l i k e l y to be d i f f e r e n t . The t o t a l number of b r a i n tumour p a t i e n t s seen a t LGH d u r i n g the f o u r twelve-month study p e r i o d s was 52 T a b l e 4.3: S i z e of Study Groups. STUDY PERIOD (Year) BRAIN TUMOUR GROUP CEREBROVASCULAR DISEASE GROUP POPULATION STUDY GROUP POPULATION STUDY GROUP 1973 10 a l l 151 a l l 1977 12 a l l 249 150 1981/2 24 a l l 290 150 1983/4 39 a l l 294 156 s m a l l and a l l were i n c l u d e d i n the s t u d y . For the c e r e b r o -v a s c u l a r d i s e a s e group, because the p a t i e n t p o p u l a t i o n s are much l a r g e r , s a m p l i n g was n e c e s s a r y i n t h r e e of the f o u r study p e r i o d s . The sample s i z e r e q u i r e d i s 45-47 c a l c u l a t e d to be one hundred and f o r t y - n i n e . D e t a i l s of the c a l c u l a t i o n are shown i n Appendix A. Random sampli n g was c a r r i e d o u t . The a c t u a l s i z e s of the v a r i o u s study groups a re shown i n Table 4.3. 4.6 DATA SOURCE AND COLLECTION I n s t i t u t i o n a l d ata on LGH were e x t r a c t e d from r e c o r d s kept by the M e d i c a l Records Department and the Department of D i a g n o s t i c Imaging, as w e l l as from v a r i o u s m e d i c a l s t a f f r e p o r t s . The r e l e v a n t p a t i e n t p o p u l a t i o n s were d e r i v e d from the H o s p i t a l M e d i c a l Records I n s t i t u t e 53 (HMRI) r e p o r t s . These HMRI r e p o r t s a re s u b m i t t e d by LGH to the B r i t i s h Columbia M i n i s t r y of H e a l t h on an annual b a s i s . S p e c i f i c p a t i e n t data needed f o r t h i s s tudy were e x t r a c t e d from i n d i v i d u a l p a t i e n t c h a r t s . The p a t i e n t c h a r t i n f o r m a t i o n e x t r a c t form i s shown i n Appendix B. In or d e r t o make sure t h a t no n e u r o l o g i c a l t e s t s were o v e r -l o o k e d , p a r t i c u l a r a t t e n t i o n was p a i d t o l a b o r a t o r y r e p o r t s , r e f e r r a l l e t t e r s , a d m i s s i o n h i s t o r i e s , c o n s u l t -a t i o n notes and d i s c h a r g e summaries. 4 . 7 STATISTICAL ANALYSIS T h i s study was undertaken t o determine i f t h e r e was any change i n the p a t t e r n of u t i l i z a t i o n of neuro-d i a g n o s t i c t e s t s f o l l o w i n g the i n t r o d u c t i o n of CT. The p r o p o r t i o n s of p a t i e n t s who were exposed t o t h e s e t e s t s , b e f o r e and a f t e r the a v a i l a b i l i t y of CT, were compared. T h i s method of comparison was used i n the U n i v e r s i t y of 41 Washington s t u d y . S i n c e the performances of n e u r o l o g i c a l t e s t s were s i m p l e d i c h o t o m i e s (yes or n o ) , we s h a l l a p p l y the C h i - s q u a r e T e s t t o a n a l y z e the d a t a . The o r i g i n a l oC i n t e n d e d was 0.05. However, because the C h i -square T e s t w i l l be used t w e l v e t i m e s , we s h a l l have to a d j u s t f o r t h i s m u l t i p l e comparison problem by changing < to 0.004. The r a t i o n a l e behind t h i s adjustment i s t h a t 54 t h e c h a n c e o f f i n d i n g a s t a t i s t i c a l l y s i g n i f i c a n t r e s u l t i n c r e a s e s w i t h t h e f r e q u e n c y o f s t a t i s t i c a l t e s t i n g . I t s h o u l d b e p o i n t e d o u t t h a t n o n e o f t h e s t u d i e s r e v i e w e d h a d m a d e a n y a d j u s t m e n t f o r m u l t i p l e c o m p a r i s o n . I f t h i s w e r e d o n e , t h e n m o s t o f t h e s u p p o s e d l y " s t a t i s t i c a l l y s i g n i f i c a n t " f i n d i n g s w o u l d n o t b e s o . 55 C H A P T E R 5 R E S U L T S 5.1 I N T R O D U C T I O N In t h i s c h a p t e r , data on the u t i l i z a t i o n of n e u r o - d i a g n o s t i c t e s t s w i l l be p r e s e n t e d f i r s t a t the i n s t i t u t i o n a l l e v e l and then a t the p a t i e n t group l e v e l . These n e u r o - d i a g n o s t i c t e s t s i n c l u d e EEG, s k u l l X -ray, c e r e b r a l angiogram, pneumoencephalogram, n u c l e a r b r a i n scan and CT b r a i n s c a n . I t i s i m p o r t a n t to a s s e s s data a t both l e v e l s . U t i l i z a t i o n t r e n d s a t the p a t i e n t group l e v e l might not be the same as those a t the i n s t i t u t i o n a l l e v e l because i n s t i t u t i o n a l data are aggregate d a t a from a l l p a t i e n t groups. F u r t h e r m o r e , f i n d i n g s a t the p a t i e n t group l e v e l a r e more u s e f u l t o p h y s i c i a n s who w i l l c o n s i d e r such f i n d i n g s when making f u t u r e c l i n i c a l d e c i s i o n s , whereas f i n d i n g s at the i n s t i t u t i o n a l l e v e l tend to have more s i g n i f i c a n c e f o r a d m i n i s t r a t o r s and p l a n n e r s when they have to make d e c i s i o n s on p o l i c y or r e s o u r c e a l l o c a t i o n . We s h a l l a l s o l o o k a t the economic impact by comparing the average c o s t of n e u r o l o g i c a l t e s t s on a per p a t i e n t b a s i s over the study p e r i o d from 1973 to 1983/4. 5.2 P R O V I N C I A L DATA Table 5.1 shows the number and r a t e of neuro-56 l o g i c a l a d m i s s i o n s f o r the P r o v i n c e of B r i t i s h Columbia f o r the y e a r s 1973, 1977, 1981/2 and 1982/3. The f i g u r e s f o r 1983/4 have not yet been r e l e a s e d . These d a t a p r o v i d e a background f o r l o o k i n g a t the LGH d a t a . Over t h i s p e r i o d 1973 to 1982/3, w h i l e the popu-l a t i o n of B r i t i s h Columbia i n c r e a s e d by 20.5%, the number of b r a i n tumour and c e r e b r o v a s c u l a r d i s e a s e a d m i s s i o n s had i n c r e a s e d by 69.1% and 26.7% r e s p e c t i v e l y . On a r a t e b a s i s , b r a i n tumour a d m i s s i o n s r o s e by 40.2% w h i l e c e r e b r o v a s c u l a r a d m i s s i o n s r o s e by o n l y 5.2%. T h i s n o t i c e a b l e i n c r e a s e i n the r a t e of b r a i n tumour a d m i s s i o n s c o u l d be due to a number of f a c t o r s . F i r s t , i t c o u l d be the r e s u l t of improved c a s e - f i n d i n g i n which CT might have p l a y e d a p a r t . Second, i t c o u l d be due to changes i n the p a t t e r n of a d m i s s i o n s subsequent t o changes i n t h e r a p e u t i c methods and to the emphasis on s h o r t e r h o s p i t a l s t a y s . T h i r d , i t c o u l d be the r e s u l t of an i n c r e a s e i n the s u r v i v a l r a t e of b r a i n tumour p a t i e n t s who would p r o b a b l y r e q u i r e more r e - a d m i s s i o n s f o r f u r t h e r t r e a t m e n t . I d e a l l y , i t would be i n t e r e s t i n g to c o r r e l a t e the above p r o v i n c i a l data on n e u r o l o g i c a l a d m i s s i o n s w i t h the p r o v i n c i a l data on the number of n e u r o l o g i c a l t e s t s done over the same p e r i o d . U n f o r t u n a t e l y , the p r o v i n c e had not been c o l l e c t i n g such data u n t i l r e c e n t l y , and the a c c u r a c y of these d a t a i s by no means c e r t a i n . 57 Table 5 .1: Neurological Admissions for Province of B r l t i a h Columbia. ADMISSIONS* PERCENTAGE INCREASE 1973 1977 1981/2 1982/3 1973-1982/3 NUMBER RATE** NUMBER RATE** NUMBER RATE** NUMBER RATE** NUMBER RATE** BRAIN TUMOUR GROUP (ICD-9 191, 198 and 225). 391 1.69 566 2.27 718 2.62 661 2.37 69.1% 40.2% CEREBROVASCULAR DISEASES GROUP (ICD-9: 430-8). 5,822 25.14 6,624 26.52 7,314 26.65 7,379 26.45 26.7% 5.2% POPULATION OF BRITISH COLUMBIA 2,315,000 2,497,600 2,744,465 2,790,532 20.5% Including Re-Admissions. ** Per Ten Thousand Population. Source: Research D i v i s i o n , Hospital Programs, S t a t i s t i c s of Hospital Cases  Discharges, 1973, 1977, 1981/2, 1982/3, Minis t ry of Health, Province of B r i t i s h Columbia. 5.3 INSTITUTIONAL DATA Table 5.2 shows the number of neurological patients who were admitted, for the f i r s t time, to LGH during the years 1973, 1977, 1981/2 and 1983/4. Over the period 1973 to 1983/4, there was an increase of 290% for the brain tumour group, and an increase of 94.7% for the cerebrovascular group. However, a si g n i f i c a n t portion of this increase was due to ref e r r a l s from areas beyond the North Shore (see Tables 5.4 and 5.5). If we remove these r e f e r r a l s and just look at the admissions of North Shore Table 5.2: Number of First-Admission  Neurological Patients. CLASSIF-ICATION NUMBER OF PATIENTS PERCENTAGE INCREASE 1973 1977 1981/2 1983/4 1973-1983/4 BRAIN TUMOUR GROUP (ICD-9: 191, 198 225) 10 12 24 39 290.0 CEREBRO-VASCULAR DISEASE GROUP (ICD-9: 430-438) 151 249 290 294 94.7 Source: Medical Records Department, Lions Gate Hospital. 59 r e s i d e n t s , then the a d j u s t e d i n c r e a s e s were 60% f o r the b r a i n tumour group and 72% f o r the c e r e b r o v a s c u l a r group. These f i g u r e s r e f l e c t e d the f a c t t h a t , over t h i s p e r i o d , LGH was g r a d u a l l y becoming a c e n t r e of r e f e r r a l f o r such p a t i e n t s and had been drawing them both from the N o r t h Shore and from a r e a s beyond i t . I t i s expected t h a t t h i s i n c r e a s e i n a d m i s s i o n s would have a c o n s i d e r a b l e impact on the aggregate i n s t i t u t i o n a l data on the u t i l i z a t i o n of n e u r o l o g i c a l t e s t s . T a ble 5.3 shows the f r e q u e n c y of n e u r o d i a g n o s t i c procedures c a r r i e d out a t LGH. These were aggregate data f o r a l l t y p e s of p a t i e n t s . D u r i n g the y e a r s 1977 and 1981/2, p a t i e n t s who r e q u i r e d CT were t r a n s f e r r e d to o t h e r h o s p i t a l s f o r t h e i r s c a n s . U n f o r t u n a t e l y , d a t a r e g a r d i n g the number of such t r a n s f e r s were not a v a i l a b l e . Over the p e r i o d 1973 t o 1983/4, t h e r e was a s m a l l i n c r e a s e of EEGs by 17.3% and a moderate i n c r e a s e of c e r e b r a l angiograms by 31.2%. I t s h o u l d be noted t h a t the i n c r e a s e i n c e r e b r a l angiograms a c t u a l l y took p l a c e between 1973 and 1977. Over the p e r i o d 1973 to 1983/4, s k u l l x - r a y s f e l l by 16.3%. However, between 1973 and 1981/2, i t a c t -u a l l y i n c r e a s e d by 10.3% p e r c e n t . The f a l l took p l a c e between 1981/2 and 1983/4, when i t f e l l by 24.1%. T h i s s u g g e s t s t h a t the i n s t a l l a t i o n of the in-house CT scanner 60 Table 5.3: Frequency of Neuro-Diagnostic Tests at LGH. TEST NUMBER OF TESTS PERCENTAGE INCREASE 1973 1977 1981/2 1983/4 1973-1983/4 EEG 934 1004 1 ,001 1,096 + 17.3 SKULL X-RAY 865 932 954 724 - 16.3 CEREBRO-ANGIO-GRAM 215 294 277 282 + 31.2 PNEUMOEN-CEPHALO-GRAM 71 16 0 0 - 100.0 NUCLEAR BRAIN SCAN CT BRAIN SCAN 662 0 885 * N. A. 548 * N.A. 179 2,013 - 73.0 * Data on patients who were transferred to other hospitals for CT were not available. Sources: 1. Department of Imaging, LGH. 2. Medical Staff Reports, LGH, (1973, 1977, 1981/2, 1983/4). at LGH in 1982 prompted physicians to choose CT instead of skull x-ray as a screening procedure for certain groups of neurological patients. Nuclear brain scans increased during the f i r s t part of the period and then f e l l substantially between 61 1977 and 1983/4. The o v e r a l l r a t e of decrease over the whole p e r i o d was 73%. Pneumoencephalograms were c o m p l e t e l y r e p l a c e d . None were done i n the y e a r s 1981/2 and 1983/4. In the f i r s t f u l l f i s c a l year of o p e r a t i o n of the CT scanner a t LGH (1983/4), t h e r e were 2,013 CT b r a i n s c a n s , making i t the most f r e q u e n t n e u r o - d i a g n o s t i c p r o -cedure a t the h o s p i t a l . T h i s r a p i d a c c e p t a n c e by p h y s i c i a n s i s p r o b a b l y due to the f a c t t h a t even b e f o r e 1982, they were a l r e a d y f a m i l i a r w i t h CT when they t r a n s -f e r r e d p a t i e n t s to o t h e r h o s p i t a l s f o r s c a n n i n g . 5 .4 STUDY GROUP CHARACTERISTICS T a b l e s 5.4 and 5.5 p r e s e n t data on the study group c h a r a c t e r i s t i c s f o r the b r a i n tumour p a t i e n t s and c e r e b r o v a s c u l a r d i s e a s e p a t i e n t s r e s p e c t i v e l y . I t s h o u l d be p o i n t e d out t h a t because of the s m a l l s i z e of the b r a i n tumour groups, v a r i a t i o n i n i n d i v i d u a l p a t i e n t c h a r a c t e r i -s t i c s would a f f e c t the group c h a r a c t e r i s t i c s c o n s i d e r a b l y . There were more males than females i n the b r a i n tumour groups w h i l e the numbers were r o u g h l y e q u a l i n the c e r e b r o v a s c u l a r d i s e a s e groups. The b r a i n tumour p a t i e n t s were, on average, younger than the c e r e b r o v a s c u l a r d i s e a s e p a t i e n t s . 62 T a b l e 5.4: H o s p i t a l i s e d B r a i n Tumour P a t i e n t s (ICD-9: 191, 198 and 225) . CHARACTERISTICS 1973 1977 1981/2 1983/4 PATIENTS IN STUDY GROUP (Number) 10 12 24 39 MALE/FEMALE ( R a t i o ) 1.5 2.0 1.2 1.3 AGE (Year) Mean Median Standard D e v i a t i o n 47.1 46.5 19.4 56.3 58.0 16.3 53.3 55.0 15.7 57.0 62.0 19.8 HOSPITAL STAY (Days) Mean Median Standard D e v i a t i o n 15.1 14.5 9.4 19.8 16.5 13.8 23.3 17.5 20.3 29.6 13.0 55.1 PLACE OF RESIDENCE (%) No r t h Shore G r e a t e r Vancouver ( e x c e p t N o r t h Shore) Others 100 0 0 58.3 41.7 0 50.0 37.5 12.5 41.0 35.9 23.1 PHYSICIAN SPECIALITY (%' Fa m i l y P r a c t i t i o n e r I n t e r n i s t N e u r o l o g i s t Neurosurgeon 50 0 0 50 33.3 8.3 0 58.3 20.8 0 8.3 70.8 5.1 5.1 15.4 74.4 HOSPITAL DEATHS (%) 10 16.7 12.5 12.8 63 Table 5.5: H o s p i t a l i s e d C e r e b r o v a s c u l a r D i s e a s e P a t i e n t s (ICD-9: 430 t o 438). CHARACTERISTICS 1973 1977 1981/2 1983/4 PATIENTS IN STUDY GROUP (Number) 151 150 150 156 MALE/FEMALE ( R a t i o ) 0.9 1.1 0.9 0.9 AGE (Year) Mean Median Standard D e v i a t i o n 71.7 75.0 14.6 69.2 69.5 13.8 69.3 70.0 14.6 68.3 71.0 14.0 HOSPITAL STAY (Days) Mean Median Standard D e v i a t i o n 19.8 9.0 26.4 31.2 15.0 38.3 19.7 8.5 29.9 20.6 11.0 28.5 PLACE OF RESIDENCE (%) No r t h Shore G r e a t e r Vancouver ( e x c e p t N o r t h Shore) Others 85.4 7.9 6.6 81.3 10.7 8.0 82.0 8.0 10.0 75.6 12.8 11.5 PHYSICIAN SPECIALITY (% Fa m i l y P r a c t i t i o n e r I n t e r n i s t G e n e r a l Surgeon N e u r o l o g i s t Neurosurgeon Others ) 80.1 11.3 2.6 2.0 3.3 0.7 68.0 12.7 0.7 1.3 17.3 0 76.0 0.7 1.3 7.3 14.8 0.7 67.9 1.9 5.1 9.0 14.7 1.3 HOSPITAL DEATHS (%) 38.5 26.1 30.4 22.8 64 Over the p e r i o d 1973 to 1983/4, t h e r e was a s l i g h t but g r a d u a l i n c r e a s e i n the l e n g t h of h o s p i t a l s t a y of b r a i n tumour p a t i e n t s . However i n 1983/4, t h e r e were two p a t i e n t s who were h o s p i t a l i s e d f o r 113 days and 156 days r e s p e c t i v e l y , thus i n f l a t i n g the average l e n g t h of s t a y f o r t h a t y e a r . For c e r e b r o v a s c u l a r d i s e a s e p a t i e n t s t h e r e was l i t t l e change i n the l e n g t h of s t a y over the whole p e r i o d . However, the l e n g t h of s t a y was a b n o r m a l l y h i g h i n 1977 due to a s i g n i f i c a n t number of l o n g - s t a y p a t i e n t s . (Out of a t o t a l of 150 p a t i e n t s , 6 p a t i e n t s s t a y e d more than a hundred days and 23 p a t i e n t s s t a y e d between f i f t y and a hundred days.) An i n c r e a s i n g percentage of b r a i n tumour p a t -i e n t s were coming from o u t s i d e of the N o r t h Shore. At the same t i m e , t h e r e was an o b v i o u s d e c l i n e i n the percentage of f a m i l y p r a c t i t i o n e r s b e i n g the p h y s i c i a n - i n - c h a r g e , w h i l e t h e r e was an i n c r e a s e i n the p ercentage of p a t i e n t s under neurosurgeons. S i m i l a r changes were a l s o seen i n c e r e b r o v a s c u l a r d i s e a s e p a t i e n t s , however, they were l e s s marked; the percentage of f a m i l y p r a c t i t i o n e r s a l s o dropped s l i g h t l y from 80.1% i n 1973 t o 67.9% i n 1983/4, w i t h i n c r e a s e s i n the p e r c e n t a g e s of both n e u r o l o g i s t s and n eurosurgeons. The above changes suggested an o b v i o u s s h i f t from f a m i l y p r a c t i t i o n e r s to s p e c i a l i s t s . 65 I t i s i n t e r e s t i n g to note t h a t the r a t e of hos-p i t a l deaths had d e c l i n e d by 41% i n the c e r e b r o v a s c u l a r d i s e a s e p a t i e n t s . T h i s c o u l d be due t o improved ( f i r s t -a d m i s s i o n ) p a t i e n t s u r v i v a l . For the b r a i n tumour p a t -i e n t s , the r a t e of ( f i r s t - a d m i s s i o n ) h o s p i t a l deaths had i n c r e a s e d s l i g h t l y . However, the numbers were too s m a l l to show a m e a n i n g f u l t r e n d . Note t h a t the p r o v i n c i a l data ( S e c t i o n 5.2) had suggested an i n c r e a s e i n the s u r v i v a l r a t e of b r a i n tumour p a t i e n t s . Thus, i f we assume both o b s e r v a t i o n s t o be c o r r e c t , then we c o u l d p o s t u l a t e t h a t t h i s i n c r e a s e i n s u r v i v a l r a t e of b r a i n tumour p a t i e n t s o n l y o c c u r r e d i n those who s u r v i v e d t h e i r f i r s t a d m i s s i o n . 5.5 FREQUENCY OF NEUROLOGICAL TESTS IN STUDY GROUPS T a b l e s 5.6 and 5.7 p r o v i d e the f r e q u e n c i e s of n e u r o l o g i c a l t e s t s f o r the b r a i n tumour group and the c e r e b r o v a s c u l a r d i s e a s e group r e s p e c t i v e l y . Over the e n t i r e study p e r i o d , CT had i n c r e a s e d r a p i d l y , so t h a t by 1983/4 i t accounted f o r h a l f of a l l n e u r o l o g i c a l t e s t s done on both groups of p a t i e n t s . L o o k i n g a t the t r e n d s of the u t i l i z a t i o n of t hese t e s t s over the study p e r i o d , t h e r e are o b v i o u s d i f -f e r e n c e s between th e s e two groups of p a t i e n t s . For the b r a i n tumour group, over the p e r i o d 1973 to 1983/4 ( w i t h the e x c e p t i o n of CT), the u t i l i z a t i o n of a l l n e u r o l o g i c a l 66 Table 5.6: Frequency of N e u r o l o g i c a l Testa i n the B r a i n Tumour Group. 1973 1977 1981/2 1983/4 Number of Tests % P a t i e n t With Test Number of Tests % P a t i e n t With Test Number of Tests % P a t i e n t With Test Number of Tests % P a t i e n t With Test EEG 9 90 7 50 9 33.3 11 23.1 SKULL X-RAY 8 80 3 25 6 25.0 10 23.1 CEREBRAL ANGIOGRAM 8 80 10 75 16 66.7 22 56.4 PNEUMOENCEPHALOGRAM 4 40 0 0 0 0 0 0 NUCLEAR BRAIN SCAN 5 50 4 33.3 5 20.8 0 0 CT BRAIN SCAN 0 0 5 41.7 22 66.7 47 76.9 Table 5.7: Frequency of N e u r o l o g i c a l Teats i n the Cerebrovascular Disease Group. 1973 1977 1981/2 1983/4 Number of Tests % P a t i e n t With Test Number of Teats % P a t i e n t With Test Number of Testa % P a t i e n t With Test Number of Testa % P a t i e n t With Test EEG 48 29.8 65 39.3 63 41.3 38 23.7 SKULL X-RAY 35 21.9 42 27.3 33 20.7 19 12.2 CEREBRAL ANGIOGRAM 29 10.6 41 24.0 38 21.3 56 28.2 PNEUMOENCEPHALOGRAM 6 4.0 1 0.7 0 0 0 0 NUCLEAR BRAIN SCAN 40 25.8 55 34.7 56 36.0 5 3.2 CT BRAIN SCAN 0 0 7 4.7 42 27.3 112 59.6 t e s t s f e l l . In g e n e r a l , t h i s d e c r e a s e , as i n d i c a t e d by the 1977 f i g u r e s , o c c u r r e d r e a s o n a b l y e a r l y . Most t e s t s c o n t i n u e d t o d e c l i n e a f t e r 1977, except f o r s k u l l X-ray which remained unchanged and f o r pneumoencephalogram which had a l r e a d y dropped to n i l i n 1977. For the c e r e b r o -v a s c u l a r d i s e a s e p a t i e n t s , the u t i l i z a t i o n of these t e s t s d e c l i n e d much l a t e r . A c t u a l l y , EEG, and n u c l e a r b r a i n scan rose between 1973 and 1981/2, and then f e l l a f t e r 1981/2. The u t i l i z a t i o n of s k u l l X-ray a l s o r o s e i n 1977 and then dropped a f t e r t h a t . Pneumoencephalogram was the e x c e p t i o n i n t h a t most of i t s decrease o c c u r r e d b e f o r e 1977. C e r e b r a l angiogram d i d not f o l l o w the g e n e r a l 48 p a t t e r n and appeared not to have been a f f e c t e d by CT. T h i s o b s e r v a t i o n w i l l be e l a b o r a t e d i n the next c h a p t e r . These p a t t e r n s of u t i l i z a t i o n of the neuro-l o g i c a l t e s t s c o u l d be e x p l a i n e d by l o o k i n g a t the u t i l i -z a t i o n of CT. In the b r a i n tumour group, CT was a l r e a d y w i d e l y u t i l i z e d i n 1977. However, i n the c e r e b r o v a s c u l a r d i s e a s e group, t h i s d i d not occur u n t i l 1981/2. T h i s t e m p o r a l r e l a t i o n s h i p between the i n c r e a s e i n CT and the decrease i n the o t h e r t e s t s s u g gests a replacement e f f e c t of CT. The s t a t i s t i c a l a n a l y s e s of the o v e r a l l changes i n f r e q u e n c y of the u t i l i z a t i o n of n e u r o l o g i c a l t e s t s f o r both groups of p a t i e n t s are shown i n Table 5.8. A l t h o u g h 69 Table 5.8: Statistical Analyses of Overall Changes in Frequency of  Utilization of Neurological Tests (1973 - 1983/4). BRAIN TUMOUR GROUP CEREBROVASCULAR DISEASE GROUP DIAGNOSTIC TEST NUMBER OF PATIENTS WITH TEST 2 x VALUE SIGNIFICANCE NUMBER OF PATIENTS WITH TEST 2 x VALUE SIGNIFICANCE 1973 1983/4 1973 1983/4 EEG 9 9 12.59 0.0004 45 37 1.16 0.282 SKULL X-RAY 8 9 9 0.0027 33 19 4.44 0.035 CEREBRAL ANGIOGRAM 8 22 1 0.03 16 44 14.03 0.0002 PNEUMOENCEPHALOGRAM 4 0 12 0.0005 6 0 4.41 0.03 NUCLEAR BRAIN SCAN 5 0 16.60 < 0.0001 39 5 30 < 0.0001 CT BRAIN SCAN 0 30 16.73 < 0.0001 0 93 126 < 0.0001 TOTAL NUMBER OF PATIENTS 10 39 151 156 the power i s l e s s i n the b r a i n tumour group because of i t s s m a l l s i z e , f o r t u n a t e l y most of the observed d e c r e a s e s i n the u t i l i z a t i o n of n e u r o l o g i c a l t e s t s were l a r g e thus making them s t a t i s t i c a l l y s i g n i f i c a n t . I f one uses 0.004 as the c u t - o f f l e v e l of s i g n i f i c a n c e (as d i s c u s s e d i n S e c t i o n 4.7), then the r e s u l t s f o r EEG, s k u l l X -ray, pneumoencephalogram, n u c l e a r b r a i n scan and CT b r a i n scan i n the b r a i n tumour group, and the r e s u l t s f o r c e r e b r a l angiogram, n u c l e a r b r a i n scan and CT b r a i n scan i n the c e r e b r o v a s c u l a r d i s e a s e group, can be re g a r d e d as b e i n g s t a t i s t i c a l l y s i g n i f i c a n t . A l t h o u g h pneumoencephalogram d i d not a c h i e v e s t a t i s t i c a l s i g n i f i c a n c e when i t s u t i l i z a -t i o n f e l l from 4% to 0% ( T a b l e 5.7), t h i s f a l l i s c l e a r l y of p r a c t i c a l s i g n i f i c a n c e s i n c e i t showed an ob v i o u s t r e n d . When we speak of an observed change b e i n g s t a t -i s t i c a l l y s i g n i f i c a n t we mean t h a t t h i s change i s u n l i k e l y 49 t o o ccur by chance. However, the l e v e l of s i g n i f i c a n c e i s a r b i t r a r i l y s e t . In most m e d i c a l s t u d i e s , the l e v e l i s u s u a l l y s e t a t p = 0.05 w i t h o u t a d j u s t i n g f o r the m u l t i p l e comparison problem as d i s c u s s e d i n S e c t i o n 4.7. I f we had used t h i s s i g n i f i c a n c e l e v e l of 0.05, then i n t h i s study almost a l l of the observed changes i n n e u r o l o g i c a l t e s t s u t i l i z a t i o n would have been s t a t i s t i c a l l y s i g n i f i c a n t . 71 5.6 IMPACT ON TOTAL COST OF NEUROLOGICAL TESTS As a l r e a d y d i s c u s s e d u n d e r S e c t i o n 3.3 o f t h i s t h e s i s , r e s i d e n t s o f Canada a r e c o v e r e d by a p u b l i c m e d i c a l i n s u r a n c e scheme a d m i n i s t e r e d by t h e p r o v i n c i a l g o v e r n m e n t . T h u s , t h e t e r m " c o s t " means c o s t t o t h e p r o -v i n c i a l g o v e r n m e n t a s i t i s t h e p a y e r f o r h e a l t h c a r e r e c e i v e d by t h e i n d i v i d u a l . T a b l e 5.9 l i s t s t h e f e e s c h a r g e d by p h y s i c i a n s f o r t h e p e r f o r m a n c e o f t h e v a r i o u s n e u r o l o g i c a l t e s t s . S u c h f e e s a r e n e g o t i a t e d b e t w e e n t h e B r i t i s h C o l u m b i a M e d i c a l A s s o c i a t i o n and t h e P r o v i n c i a l G o v e r n m e n t o f B r i t i s h C o l u m b i a on an a n n u a l b a s i s . E a c h f e e i s composed o f a p r o f e s s i o n a l component ( p h y s i c i a n c o s t ) and a t e c h n i c a l component ( a l l o t h e r c o s t s ) . H owever, a c c o r d i n g t o t h e B r i t i s h C o l u m b i a M i n i s t r y o f H e a l t h , t h i s d i v i s i o n i n t o t h e two c o m p o n e n t s i s a r b i t r a r y and i s b a s e d on c o n s e n s u s r a t h e r t h a n on a c t u a l c o s t s t u d i e s . U s i n g t h i s f e e s c h e d u l e and a p p l y i n g i t t o t h e a v e r a g e number o f t e s t s p e r p a t i e n t , one c a n c a l c u l a t e and compare t h e a v e r a g e c o s t o f i n v e s t i g a t i n g an i n d i v i d u a l p a t i e n t i n e a c h o f t h e f o u r s t u d y p e r i o d s . I n o r d e r t o compare t h e c o s t s i n e a c h o f t h e f o u r p e r i o d s on an e q u a l b a s i s , t h e f e e s c h e d u l e f o r t h e l a t e s t p e r i o d o f t h e s t u d y ( 1 9 8 3 / 4 ) was u s e d t o c a l c u l a t e a l l c o s t s . The r e s u l t s a r e shown i n T a b l e s 5.10 and 5.11. 72 Table 5.9: Fee Schedule of Neurological Diagnostic Procedures 1973 1977 1981/2 1983/4 TECHNICAL PROFESSIONAL TOTAL TECHNICAL PROFESSIONAL TOTAL TECHNICAL PROFESSIONAL TOTAL TECHNICAL PROFESSIONAL TOTAL EEG 26.9 10.7 37.6 39.1 12.5 51.6 57.3 18 75.3 65.3 20.6 85.9 SKULL X-RAY 12.9 18.3 14.9 5.8 20.7 37.7 8.4 32.1 27 9.6 36.6 ANGIOGRAM 26.9 10.7 37.6 35.4 13 48.4 56.4 26.1 82.5 64.3 29.8 94.1 PNEUMOENCEPHALOGRAM 26.3 11.3 37.6 34.7 13.7 48.4 55.2 19.2 74.4 62.9 21.9 84.8 NUCLEAR BRAIN SCAN * 64.5 21.5 86.0 77.4 25.0 102.4 113.7 33.82 147.5 ! 129.6 38.55 168.15 CT (without contrast) • (58.5) (19.5) (78) (90) 30 120) (102.6) 34.2 136.8] CT (with contrast) (77.5) (31.4) 108.9 (125.7) 41.9 p 1 (143.4) 47.8 1 191.2 * CT is a special case. Starting in 1981/2, the government only reimbursed the professional com-ponent, the technical component was absorbed by the hospital (being part of the global funding from government). For the sake of comparison, the figures in brackets were derived with the following assumptions: 1. The professional component was 25% of the total cost which was the usual case for the other procedures. 2. The government did not pay any fee in 1977. The figures was arbitrari ly derived from figures for 1981/2 using the same proportional discount as for the other procedures (1977 fee/1981-2 fee = 0.65). Source: Brit i sh Columbia Medical Association. Table 5.10: Average Cost of Neur o l o g i c a l Teats per Brain Tumour Patient ( i n 1983/4 f e e - d o l l a r s ) . NEUROLOGICAL DIAGNOSTIC PROCEDURE FEE PER TEST 1983/4 1973 1977 1981/2 1983/4 AVERAGE NUMBER OF TEST PER PATIENT COST AVERAGE NUMBER OF TEST PER PATIENT COST AVERAGE NUMBER OF TEST PER PATIENT COST AVERAGE NUMBER OF TEST PER PATIENT COST EEG 85 90 0 9 77 31 0 58 49 82 0 .38 32 64 0. 28 24.05 SKULL X-RAY 36 60 0 8 29 .28 0 25 9 15 0 .25 9 15 0.26 9.52 CEREBRAL ANGIOGRAH 94 10 0 a 75 28 0 83 78 10 0 .67 63 05 0.56 52.70 PNEUMOENCEPHALOGRAM 84 80 0 4 33 92 0 0 0 0 0 0 NUCLEAR BRAIN SCAN 168 15 0 5 84 08 0 33 55 49 0 .21 35 31 0 0 CT BRAIN SCAN 180. 32* 0 0 0 42 75 73 0 .92 165 89 1.21 218.19 TOTAL 3. 4 299 87 2. 41 268.29 2 .43 306 04 2.31 304.46 27 * I t has been estimated that roughly 80% of CT studies were done with co n t r a s t . Therefore, the fee f o r CT i s a weighted-average of the fees f o r CT with contrast and without c o n t r a s t . Table 5.11: Average Coat of Neurological Teats per Cerebrovascular Disease Patient ( i n 1983/4 f e e - d o l l a r s ) . -4 NEUROLOGICAL DIAGNOSTIC PROCEDURE 1973 1977 1981/2 1983/4 FEE PER TEST 1983/4 AVERAGE NUMBER OF TEST PER PATIENT COST AVERAGE NUHBER OF TEST PER PATIENT COST AVERAGE NUHBER OF TEST PES PATIENT COST AVERAGE NUMBER OF TEST PER PATIENT COST EEG 85 90 0 32 27 50 0 43 36 94 0.42 36.08 0.24 20.62 SKULL X-RAY 36 60 0 23 8 42 0 28 10 25 0.22 8.05 0.12 4.39 CEREBRAL ANGIOGRAM 94 10 0 19 17 88 0 27 25 41 0.25 23.53 0.36 33.88 PNEUMOENCEPHALOGRAM 84 80 0 04 3 .39 0 01 0 B5 0 0 0 0 NUCLEAR BRAIN SCAN 168 15 0 26 43 72 0 37 62 22 0.37 62.22 0.03 5.04 CT BRAIN SCAN 180 32* 0 0 0 05 9 02 0.28 50.49 0.72 129.83 TOTAL 1 04 131 44 1 41 144 67 1 .54 180.36 1.11 193.76 27 * I t has been estimated that roughly 80% of CT atudies were done with c o n t r a s t . Therefore, the fee fo r CT i a a weighted-average of the fees f o r CT with contrast and without c o n t r a s t . For the b r a i n tumour group, each p a t i e n t i n 1973 had an average of 3.4 t e s t s . By 1983/4, t h i s had f a l l e n t o 2.3 t e s t s . However, d e s p i t e such a drop, the average c o s t had remained rem a r k a b l y c o n s t a n t t h r o u g h o u t the p e r i o d . T h i s i s due to the f a c t t h a t CT i s more ex p e n s i v e than the o t h e r t e s t s . T h e r e f o r e , even though the average number of t e s t s per p a t i e n t had d e c l i n e d , the average c o s t d i d n o t . For the c e r e b r o v a s c u l a r d i s e a s e group, the a v e r -age number of t e s t s per p a t i e n t had a c t u a l l y i n c r e a s e d between 1973 and 1981/2. Then i t s t a r t e d to d e c l i n e so t h a t by 1983/4, the average number of t e s t s was o n l y m a r g i n a l l y h i g h e r than t h a t of 1973. In t h i s group, the average c o s t showed a p e r s i s t e n t r i s e t h roughout t h i s p e r i o d from $131.44 i n 1973 to. $193.76 i n 1983/4. The r i s e i n 1977 was l a r g e l y due to the i n c r e a s e i n n u c l e a r b r a i n s c a n , w h i l e the r i s e i n 1981/2 and i n 1983/4 were due to the r a p i d i n c r e a s e i n the u t i l i z a t i o n of CT s c a n s . The above c a l c u l a t i o n of o v e r a l l c o s t s can be r e p e a t e d on the i n s t i t u t i o n a l l e v e l by a p p l y i n g the f e e sc h e d u l e f o r 1983/4 to the number of n e u r o - d i a g n o s t i c t e s t s done a t LGH ( T a b l e 5.3). However, s i n c e data on the number of CT scans f o r 1977 and 1981/2 were not a v a i l a b l e , we s h a l l not i n c l u d e these two y e a r s . The r e s u l t s are shown i n T a b l e 5.12. In terms of 1983/4 f e e - d o l l a r s , the 76 t o t a l c o s t f o r t h i s g r o up o f n e u r o - d i a g n o s t i c t e s t s had d o u b l e d o v e r t h i s p e r i o d . Table 5.12: T o t a l Coat of N e u r o l o g i c a l Teats at Lions Gate H o s p i t a l ( i n 1983/4 f e e - d o l l a r s ) . DIAGNOSTIC TESTS FEE PER TEST 1983/4 1973 1983/4 NUMBER COST NUMBER COST EEG 85.90 934 80,230.60 1,096 94,146.40 SKULL X-RAY 36.60 865 31,659.00 724 24,498.40 CEREBRAL ANGIOGRAM 94.10 215 20,231.50 282 26,536.20 PNEUMOENCEPHALOGRAM 84.80 71 6,020.80 0 0 NUCLEAR BRAIN SCAN 168.15 662 111,315.30 179 30,098.85 CT BRAIN SCAN 180.32 0 0 2,013 362,984.16 TOTAL COST 249,456.40 540,264.01 77 CHAPTER 6 DISCUSSION AND CONCLUSION 6.1 EFFECT OF CT ON NEUROLOGICAL TESTS The r e s u l t s of t h i s s tudy suggest t h a t , f o r both the b r a i n tumour and c e r e b r o v a s c u l a r groups of p a t i e n t s , CT i s a complete replacement f o r pneumoencephlography and n u c l e a r s c a n n i n g , and i s a p a r t i a l replacement f o r EEG and p l a i n s k u l l r a d i o g r a p h y . These f i n d i n g s a re i n agreement 36-41 w i t h the l i t e r a t u r e r e v iewed i n Chapter 3. In the case of c e r e b r a l a n g i o g r a p h y , p r e v i o u s s t u d i e s have shown mixed r e s u l t s . Most s t u d i e s found s m a l l to moderate d e c l i n e s i n c e r e b r a l a n g i o -36,37,38,40,41 graphy. However, o t h e r s t u d i e s found t h a t 39,48 c e r e b r a l angiography was not a f f e c t e d by CT. The r e s u l t s of t h i s s tudy show t h a t CT d i d not cause any s i g n i f i c a n t d e c l i n e i n c e r e b r a l a n g i o g r a p h y . Over the study p e r i o d 1973 to 1983/4, c e r e b r a l angiography f e l l m a r g i n a l l y ( p = 0.03 ) f o r the b r a i n tumour group, and r o s e by 160% (p = 0.0002) f o r the c e r e b r o v a s c u l a r d i s e a s e group ( T a b l e s 5.6 and 5.7). At the aggregate i n s t i t u -t i o n a l l e v e l , c e r e b r a l angiography i n c r e a s e d by 31.2% over the same p e r i o d ( T a b l e 5.3). I t s h o u l d be noted t h a t the i n c r e a s e i n c e r e b r a l angiography (as shown by both aggre-gate i n s t i t u t i o n a l and c e r e b r o v a s c u l a r d i s e a s e p a t i e n t 78 data) a c t u a l l y took p l a c e between 1973 and 1977 when c o m p a r a t i v e l y l i t t l e CT was done. T h i s o b s e r v a t i o n was 39 a l s o made by Enlow and co-workers i n the BNI s t u d y . They found t h a t b e f o r e CT was a v a i l a b l e , the u t i l i z a t i o n of c e r e b r a l angiography had i n c r e a s e d by 50% between 1973 and 1975. Comparing the pre-CT p e r i o d (1973-5) w i t h the post-CT p e r i o d (1976-8), they found t h a t the average monthly u t i l i z a t i o n of c e r e b r a l angiography had i n c r e a s e d by 32%. Based on the pre-CT t r e n d , they p r e d i c t e d t h a t i f CT were not a v a i l a b l e the i n c r e a s e i n c e r e b r a l angiography would have been even h i g h e r . T h e r e f o r e , a l t h o u g h CT d i d not show an obvi o u s e f f e c t on c e r e b r a l a n g i o g r a p h y , i t d i d a f f e c t the r a t e of i n c r e a s e of c e r e b r a l a n g iography p r o b a b l y by r e p l a c i n g i t i n s i t u a t i o n s where the i n d i c a t i o n s f o r angiography were m a r g i n a l . The observed i n c r e a s e i n the u t i l i z a t i o n of c e r e b r a l angiography by c e r e b r o v a s c u l a r d i s e a s e p a t i e n t s might have been due to the f a c t t h a t , w i t h improvements i n the t e c h n i q u e s of n e u r o - v a s c u l a r s u r g e r y , p h y s i c i a n s have been a d o p t i n g a more a g g r e s s i v e s t a n c e i n the management of t h e s e p a t i e n t s . B e f o r e a d e c i s o n can be made on p o s s i b l e s u r g i c a l t r e a t m e n t , p h y s i c i a n s need to know the l o c a t i o n of the p a t h o l o g y as w e l l as the s t a t e of the l o c a l v a s c u l a r s u p p l y . Under such c i r c u m s t a n c e s , s i n c e CT cannot p r o v i d e the r e q u i r e d i n f o r m a t i o n , c e r e b r a l angiography becomes n e c e s s a r y . ' 79 48 Bradac and Okerson compared angiography w i t h CT i n p a t i e n t s w i t h c e r e b r o - a r t e r i a l o c c l u s i v e d i s e a s e s . They concl u d e d t h a t o n l y angiography g i v e s the s e l e c t i v e s p a t i a l s o l u t i o n i n the d e m o n s t r a t i o n of c e r e b r a l v e s s e l s . In p a t i e n t s w i t h t r a n s i e n t i s c h a e m i c a t t a c k s , c a t h e t e r angiography remains the most i m p o r t a n t and n e c e s s a r y d i a g -n o s t i c s t e p . I t w i l l h e l p i n d e t e c t i n g s t e n o s i s or o c c l u -s i o n of c e r e b r a l v e s s e l s . CT, on the o t h e r hand, w i l l o n l y p r o v i d e i n f o r m a t i o n about the o v e r a l l a s p e c t of the b r a i n and a l l o w e l i m i n a t i o n of a d i f f e r e n t p a t h o l o g y . In p a t -i e n t s w i t h s t r o k e , both angiography and CT w i l l show the l o c a t i o n of the b r a i n l e s i o n , w h i l e angiography w i l l a l s o r e v e a l the p a t h o l o g i c a l c o n d i t i o n of the c e r e b r a l v e s s e l s . I n the s t a t i s t i c a l a n a l y s i s of the f i n d i n g s of t h i s s tudy ( T a b l e 5.8), those r e s u l t s which are s t a t i s t -i c a l l y s i g n i f i c a n t (p < 0.004) are EEG, s k u l l r a d i o g r a p h y , pneumoencephalography, n u c l e a r s c a n n i n g and CT s c a n n i n g f o r the b r a i n tumour group, and c e r e b r a l a n g i o g r a p h y , n u c l e a r s c a n n i n g and CT s c a n n i n g f o r the c e r e b r o v a s c u l a r d i s e a s e group. The o t h e r changes are not s t a t i s t i c a l l y s i g n i f i c a n t . A p a r t from s t a t i s t i c a l s i g n i f i c a n c e , we s h o u l d a l s o c o n s i d e r p r a c t i c a l s i g n i f i c a n c e . In o t h e r words, are the observed r e s u l t s i m p o r t a n t i n r e a l p r a c t i c e . For example, i n the c e r e b r o v a s c u l a r d i s e a s e group, over the 80 study p e r i o d 1973 t o 1983/4, the u t i l i z a t i o n of pneumoencephalography f e l l from 4% to 0% ( T a b l e 5.7), w i t h p = 0.03 ( T a b l e 5.8). A l t h o u g h t h i s change d i d not meet the r e q u i r e d s t a t i s t i c a l s i g n i f i c a n c e l e v e l of 0.004, i t d i d show a r a t h e r o b v i o u s t r e n d which was a l s o n o t i c e d i n 36-41 o t h e r s t u d i e s . T h e r e f o r e , f o r p r a c t i c a l p u rposes, t h i s f a l l i n pneumoencephalography c o u l d be r e g a r d e d as s i g n i f i c a n t and s h o u l d be c o n s i d e r e d by d e c i s i o n - m a k e r s i n t h e i r p l a n n i n g and a l l o c a t i o n of r e s o u r c e s . The r e s u l t s o b t a i n e d by t h i s s tudy have sup p o r t e d the argument t h a t i n g e n e r a l CT i s a s u b s t i t u t e f o r most n e u r o l o g i c a l t e s t s . T h e r e f o r e , d e s p i t e the d r a m a t i c i n c r e a s e i n the u t i l i z a t i o n of CT over the study p e r i o d , the average number of n e u r o l o g i c a l t e s t s per p a t i e n t d i d not show a c o r r e s p o n d i n g i n c r e a s e . A c t u a l l y , f o r the b r a i n tumour group ( T a b l e 5.10), the average number of n e u r o l o g i c a l t e s t s per p a t i e n t even f e l l from 3.4 i n the pre-CT p e r i o d (1973) to 2.3 i n the post-CT p e r i o d (1983/4). For the c e r e b r o v a s c u l a r d i s e a s e group ( T a b l e 5.11), the average number of t e s t s r o s e m a r g i n a l l y from 1.04 i n 1973 to 1.11 i n 1983/4. I t i s i n t e r e s t i n g to note t h a t the s u b s t i t u t i o n e f f e c t of CT had o c c u r r e d sooner i n the b r a i n tumour group ( T a b l e 5.6) than i n the c e r e b r o v a s c u l a r d i s e a s e group ( T a b l e 5.7). T h i s i s because the f r e q u e n t u t i l i z a t i o n of 81 CT had o c c u r r e d much e a r l i e r f o r the b r a i n tumour group. In 1977, 41.7% of b r a i n tumour p a t i e n t s and o n l y 4.7%.of c e r e b r o v a s c u l a r d i s e a s e p a t i e n t s had CT s c a n s . I t i s l i k e l y t h a t t h i s observed d i f f e r e n c e i n CT u t i l i z a t i o n between th e s e two groups of p a t i e n t s was due to the l i m i t e d a v a i l a b i l i t y of CT. In 1977, Vancouver G e n e r a l H o s p i t a l (VGH) was the o n l y h o s p i t a l i n G r e a t e r Vancouver w i t h a CT scanner ( S e c t i o n 4.4). Thus o n l y those p a t i e n t s w i t h c l e a r i n d i c a t i o n s f o r CT (such as t h o s e w i t h s u s p e c t e d b r a i n tumours) were r e f e r r e d from LGH to VGH f o r s c a n s . However, as the a v a i l a b i l i t y of CT g r a d u a l l y i n c r e a s e d , t h e r e was l e s s r a t i o n i n g , thus e n a b l i n g o t h e r p a t i e n t groups a l s o to become major u s e r s of CT. However, because CT was more e x p e n s i v e than the o t h e r t e s t s ( T a b l e 5.9), the average t o t a l c o s t of n e u r o l o g i c a l t e s t s per b r a i n tumour p a t i e n t d i d not f a l l d e s p i t e the drop i n the average number of t e s t s per p a t i e n t ( T a b l e 5.10). For t h i s group, the t o t a l c o s t of n e u r o l o g i c a l t e s t s had remained f a i r l y c o n s t a n t t h r o u g h o u t the study p e r i o d d e s p i t e changing p a t t e r n s i n the u t i l i z a t i o n of i n d i v i d u a l t e s t s . T h i s i s s i m i l a r t o the 41 f i n d i n g of the U n i v e r s i t y of Washington study which a l s o l o o k e d s p e c i f i c a l l y a t b r a i n tumour p a t i e n t s . For the c e r e b r o v a s c u l a r d i s e a s e group, the average t o t a l c o s t of n e u r o l o g i c a l t e s t s per p a t i e n t r o s e by 92% ( T a b l e 5.11). 82 T h e r e f o r e , d e s p i t e an o v e r a l l s u b s t i t u t i o n e f f e c t , CT d i d not r e s u l t i n c o s t - s a v i n g s f o r the b r a i n tumour group and was a s s o c i a t e d w i t h c o s t - i n c r e a s e s f o r the c e r e b r o v a s c u l a r d i s e a s e group. 6.2 EFFECT OF CT ON LIONS GATE HOSPITAL Over the p e r i o d 1973 to 1983/4, the aggregate i n s t i t u t i o n a l data of LGH on the f r e q u e n c y of n e u r o l o g i c a l t e s t s ( T a b l e 5.3) showed major d e c r e a s e s i n both pneumo-encephalography and n u c l e a r b r a i n s c a n n i n g , and a s l i g h t d ecrease i n s k u l l X - r a y s . On the o t h e r hand, both EEG and angiography e x p e r i e n c e d modest i n c r e a s e s , and i n the s c a n -n e r ' s f i r s t f u l l year of o p e r a t i o n (1983/4), CT became the most f r e q u e n t n e u r o l o g i c a l t e s t a t LGH. A p o i n t to note i s t h a t over t h i s p e r i o d , t h e r e was a s i z a b l e r i s e i n neuro-l o g i c a l a d m i s s i o n s ( T a b l e 5.2). T h e r e f o r e , one would e x p e c t , a l l t h i n g s b e i n g e q u a l , i n c r e a s e s s h o u l d occur i n a l l n e u r o l o g i c a l t e s t s . In terms of 1983/4 f e e - d o l l a r s , the t o t a l c o s t s of these n e u r o l o g i c a l t e s t s had r o u g h l y doubled over the study p e r i o d , r i s i n g from $249,456 i n 1973 t o $540,264 i n 1983/4 ( T a b l e 5.12). T h i s was a t t r i b u t a b l e t o CT s c a n s , the c o s t of which had i n c r e a s e d from z e r o d o l l a r s i n 1973 to $362,984 i n 1983/4, ( a c c o u n t i n g f o r 67% of t h a t y e a r ' s t o t a l c o s t s ) . However, t h i s i n c r e a s e i n t o t a l c o s t s i s 83 37 much s m a l l e r than t h a t found by the GWUMC s t u d y . A l t h o u g h t h e s e two c o s t - e s t i m a t e s were based on s l i g h t l y d i f f e r e n t c h a r g e - s c h e d u l e s ( t h e p r e s e n t study was based on p h y s i c i a n charges w h i l e the GWUMC study was based on h o s p i t a l c h a r g e s ) , we c o u l d s t i l l compare them because we are o n l y comparing the s i z e of the change i n t o t a l c o s t s i n each study r a t h e r than the a b s o l u t e d o l l a r amounts. I n the GWUMC s t u d y , Knaus, Schroeder and Davi s e s t i m a t e d t h a t the a d j u s t e d t o t a l c o s t of n e u r o - d i a g n o s t i c t e s t s had i n c r e a s e d t h r e e f o l d between 1973 and 1976. In 1976, 74% of the t o t a l c o s t was due to CT sc a n s . I t sh o u l d be noted t h a t t h i s i n c r e a s e was o n l y over f o u r y e a r s compared t o LGH's i n c r e a s e which was over e l e v e n y e a r s . T h i s d i f -f e r e n c e i n the amount of i n c r e a s e between these two s t u d i e s c o u l d be due to two re a s o n s : F i r s t , GWUMC i s a u n i v e r s i t y t e a c h i n g h o s p i t a l w h i l e LGH i s a community h o s p i t a l . We would expect more t e s t s t o he c a r r i e d out a t a u n i v e r s i t y t e a c h i n g h o s p i t a l because i t would r e c e i v e more r e f e r r a l s and would a l s o have a s i g n i f i c a n t l y h i g h e r 5 0 usage of a n c i l l a r y t e s t s on a per p a t i e n t b a s i s . Second, as d i s c u s s e d i n S e c t i o n 2.2, the r a t e of i n c r e a s e i n h e a l t h e x p e n d i t u r e s was slower i n Canada than i n the U n i t e d S t a t e s as a r e s u l t of t i g h t e r budgetary c o n t r o l f o l l o w i n g the c o m p l e t i o n of u n i v e r s a l m e d i c a l i n s u r a n c e i n 1971. T h i s was r e f l e c t e d i n the l i m i t e d a v a i l a b i l i t y of CT scanners i n Canada compared w i t h the U n i t e d S t a t e s (as 84 d i s c u s s e d i n S e c t i o n 3.3). I t would be both u s e f u l and i n t e r e s t i n g i f one c o u l d compare the aggregate data of LGH w i t h those of the p r o v i n c e , and those of s i m i l a r h o s p i t a l s i n B r i t i s h C olumbia. U n f o r t u n a t e l y , because of l i m i t a t i o n s i n t i m e , manpower and the a v a i l a b i l i t y of d a t a , t h i s i s beyond the scope of the p r e s e n t s t u d y . However, i t does p r o v i d e an i n t e r e s t i n g f i e l d t o be e x p l o r e d by f u t u r e s t u d i e s . 6.3 STUDY LIMITATIONS In the f i e l d of c l i n i c a l m e d i c i n e , the i d e a l model to demonstrate a r e l a t i o n s h i p between v a r i a b l e s or t o compare the e f f e c t s of a l t e r n a t i v e programs i s a d o u b l e - b l i n d , randomized c o n t r o l l e d t r i a l . Such a t r i a l i s n o r m a l l y s e t up because the r e s e a r c h e r s s u s p e c t t h a t a c e r t a i n p r o c e d u r e , which c o u l d be a t r e a t m e n t or a d i a g -n o s t i c p r o c e d u r e , i s s u p e r i o r to a n o t h e r . However, s i n c e the very r e a s o n f o r doing the t r i a l i m p l i e s t h a t t h e r e i s a good p o s s i b i l i t y t h a t the procedure i s b e t t e r , the p r o c e s s of r a n d o m i z a t i o n i s o f t e n r e s i s t e d by both p h y s i -c i a n s and p a t i e n t s . Many p h y s i c i a n s would c o n s i d e r i t u n e t h i c a l to w i t h h o l d from a p a t i e n t a p o s s i b l y s u p e r i o r p r o c e d u r e , even though t h i s had not been proven con-13 c l u s i v e l y i n c l i n i c a l t r i a l s . S i m i l a r l y , p a t i e n t s i n g e n e r a l do not l i k e the p o s s i b l i t y of m i s s i n g out on what 85 they p e r c e i v e t o be a b e t t e r a l t e r n a t i v e . Another problem w i t h a randomized c o n t r o l l e d t r i a l i s t h a t i t cannot be used to a s s e s s past e v e n t s . I f a r e t r o s p e c t i v e e v a l u a t i o n i s r e q u i r e d , then a r e t r o s p e c t i v e , b e f o r e - a f t e r study c o u l d be c a r r i e d o u t . As d i s c u s s e d under S e c t i o n 4 . 3 , t h i s s tudy i s a r e t r o s p e c t i v e , b e f o r e - a f t e r , comparison of the u t i l i z a t i o n of n e u r o l o g i c a l t e s t s by p a t i e n t s w i t h b r a i n tumour or c e r e b r o v a s c u l a r d i s e a s e . I d e a l l y , f o r a b e f o r e - a f t e r s t u d y , the same groups of s u b j e c t s s h o u l d be s t u d i e d b e f o r e and a f t e r exposure to the independent v a r i a b l e . T h i s i s not p o s s i b l e i n t h i s s t u d y . Here, we are a c t u a l l y comparing d i f f e r e n t p a t i e n t groups, w i t h the same d i s e a s e c l a s s i f i c a t i o n , i n d i f f e r e n t time p e r i o d s . A l t h o u g h we are i n t e r e s t e d m a i n l y i n the e f f e c t of CT on the u t i l i -z a t i o n of n e u r o l o g i c a l t e s t s , we a l s o need to c o n s i d e r the c o m p o s i t i o n of the p a t i e n t s groups ( r e g a r d i n g p a t i e n t c h a r a c t e r i s t i c s and d i a g n o s e s ) because t h i s would a f f e c t the c h o i c e of t e s t s . The assumption i s t h a t , w i t h i n each d i s e a s e c l a s s i f i c a t i o n ( b r a i n tumour or c e r e b r o v a s c u l a r d i s e a s e ) , the study groups of the f o u r time p e r i o d s would be comparable w i t h one a n o t h e r . The b e f o r e - a f t e r study i s a p r a c t i c a l and u s e f u l study d e s i g n . The r e t r o s p e c t i v e n a t u r e means t h a t a l l the dat a a re a l r e a d y a v a i l a b l e and one does not have t o w a i t , 86 as i n the case of some p r o s p e c t i v e s t u d i e s , many y e a r s be-f o r e the r e s u l t s can be f u l l y c o l l e c t e d and a n a l y z e d . A l s o , a l t h o u g h a b e f o r e - a f t e r study might not be as e f f e c t i v e as a randomized c o n t r o l l e d t r i a l i n p r o v i n g a c a u s a l r e l a t i o n s h i p between v a r i a b l e s , i t does show the time t r e n d of changes. Such i n f o r m a t i o n w i l l be u s e f u l i n the p l a n n i n g of f u t u r e manpower and f a c i l i t i e s . I n t h i s s t u d y , we have shown t h a t the u t i l i -z a t i o n of most of the n e u r o l o g i c a l t e s t s had f a l l e n f o l -l o w i n g the i n t r o d u c t i o n of CT. But can we a s c r i b e t h i s change to CT? The answer i s p r o b a b l y i n the a f f i r m a t i v e 51 because of the f o l l o w i n g o b s e r v a t i o n s : F i r s t , t h e r e was a time a s s o c i a t i o n between the i n t r o d u c t i o n of CT and the d ecrease i n the u t i l i z a t i o n of o t h e r n e u r o l o g i c a l t e s t s . Second, t h e r e was a "dose-response" r e l a t i o n s h i p , s i n c e the s i z e of the decrease i n these t e s t s appeared to be r e l a t e d to the s i z e of the i n c r e a s e i n CT scans ( T a b l e s 5.6 and 5.7). T h i r d , the s u b s t i t u t i o n e f f e c t of CT on such t e s t s as n u c l e a r b r a i n scans was o b v i o u s because of the s i z e of the observed d e c r e a s e . F o u r t h , i n g e n e r a l , the f i n d i n g s of t h i s s tudy are c o n s i s t e n t w i t h the f i n d i n g s of s i m i l a r s t u d i e s . F i f t h , our f i n d i n g s are c o h e rent w i t h e x i s t i n g c l i n i c a l p r a c t i c e . For example, i t i s now a c c e p t e d p r a c t i c e t h a t a CT scan i s a b e t t e r d i a g n o s t i c procedure than a s k u l l X-ray i n the d e t e c t i o n of i n t r a c r a n i a l haemorrhage. T h i s would have c o n t r i b u t e d 87 t o the o b s e r v e d f a l l i n s k u l l X - r a y s i n the a f t e r - C T p e r i o d . The f i n d i n g s of t h i s s t udy r e p r e s e n t e d what had happened a t LGH d u r i n g the s tudy p e r i o d 1973 to 1 9 8 3 / 4 . The q u e s t i o n i s whether such f i n d i n g s a re g e n e r a l i z a b l e to o t h e r h o s p i t a l s o f a s i m i l a r n a t u r e . The answer s h o u l d be p o s i t i v e because the r e s u l t s of t h i s s t udy a r e i n g e n e r a l agreement w i t h those o f p r e v i o u s s t u d i e s w h i c h were c a r r i e d out i n a d i v e r s i t y of h o s p i t a l s . N e v e r t h e l e s s , i t would be most i n t e r e s t i n g i f t h i s s tudy c o u l d be r e p e a t e d i n one or more of the "peer g roup" h o s p i t a l s of LGH ( h o s -p i t a l s i n B r i t i s h C o l u m b i a d e s i g n a t e d by the M i n i s t r y o f H e a l t h to be o f s i m i l a r n a t u r e to LGH i n r e s p e c t to s i z e , f a c i l i t i e s and f u n c t i o n s ) . 6 .4 CONCLUSION P a r t o f the i n c r e a s e i n the c o s t of h e a l t h c a r e has been a t t r i b u t e d to the i n c r e a s e d use o f m e d i c a l t e c h -7 n o l o g i e s . F o r example , i n the U n i t e d S t a t e s , the number of c o r o n a r y a r t e r y bypass o p e r a t i o n s has grown from v i r t u a l l y z e r o a decade ago to 110 ,000 i n 1980, and a c c o u n t s f o r 1% of a l l h e a l t h c a r e e x p e n d i t u r e s i n the 52 U n i t e d S t a t e s . L a b o r a t o r y t e s t s have grown i n volume t o such an e x t e n t t h a t t h e i r sha re o f the c o s t o f a h o s p i t a l day has i n c r e a s e d , d e s p i t e a d e c r e a s e i n the ave rage c o s t 88 53 per t e s t . A l t h o u g h a l o t of the a t t e n t i o n has been foc u s e d on new and h i g h - p r i c e d t e c h n o l o g i e s such as CT, 54 Moser i s of the o p i n i o n t h a t " i t i s the l e s s - t h a n - j u d i -c i o u s , widespread use of s m a l l - t i c k e t t e c h n o l o g i e s t h a t has c o n t r i b u t e d , i n a major, i f i n s i d i o u s manner t o the s k y r o c k e t i n g p r i c e of d i a g n o s t i c and t h e r a p e u t i c p r o c e -55 d u r e s . " T h i s view i s a l s o shared by Moloney and Rogers who c l a i m e d t h a t the b i g and h i g h l y v i s i b l e t e c h n o l o g i e s such as CT " a c t u a l l y account f o r f a r l e s s of the a n n u a l growth i n m e d i c a l e x p e n d i t u r e s than do the c o l l e c t i v e expense of thousands of s m a l l t e s t s and p r o cedures t h a t are more f r e q u e n t l y used by p h y s i c i a n s and t h a t i n d i v i -d u a l l y c o s t l i t t l e . " CT t e c h n o l o g y has improved r a p i d l y s i n c e i t s c l i n i c a l i n t r o d u c t i o n i n the e a r l y s e v e n t i e s . I t i s now an e s t a b l i s h e d component of modern m e d i c a l p r a c t i c e . For the c e n t r a l nervous system, CT i s the p r i m a r y imaging p r o c e -4,56 dure. As suggested by t h i s t h e s i s , i t has c o m p l e t e l y d i s p l a c e d pneumoencephalography and n u c l e a r b r a i n s c a n -n i n g . I t has a l s o decreased the use of o t h e r n e u r o l o g i c a l t e s t s such as EEG and s k u l l r a d i o g r a p h y . However, i t i s so e a s i l y a c c e p t e d by p h y s i c i a n s and p a t i e n t s t h a t i t runs the r i s k of becoming r o u t i n e i n p r a c t i c e . In o r d e r to a v o i d t h i s , f u r t h e r r e s e a r c h s h o u l d be encouraged to i d e n t i f y i t s a p p r o p r i a t e use. 89 The f u t u r e of CT w i l l depend on the f o l l o w i n g f a c t o r s : 1. Changes i n the c o s t of CT s c a n n i n g . T h i s w i l l depend on changes i n the p r i c e of s c a n n e r s , t h e i r o p e r a t i n g c o s t s and the f e e s charged by p h y s i c i a n s . A l o w e r i n g of the c o s t of CT s c a n -n i n g w i l l , no doubt, encourage i t s u t i l i z a t i o n . 2. New d i a g n o s t i c c a p a b i l i t y of the scanners as a r e s u l t of improved t e c h n o l o g y or new a p p l i -c a t i o n s . For example, as d i s c u s s e d i n S e c t i o n s 3.2 and 3.3, the i n c r e a s i n g d i a g n o s t i c c a p a b i l i t y of CT, p a r t i c u l a r l y i n e x a m i n a t i o n s of the abdomen, has l e d to a s i g n i f i c a n t 31,32 i n c r e a s e i n i t s u t i l i z a t i o n . 3. The development of competing d i a g n o s t i c t e c h n o -l o g i e s . A major l i m i t a t i o n of CT i s i t s i n a b i -l i t y i n most c i r c u m s t a n c e s t o p r o v i d e a s p e c i f i c p a t h o l o g i c a l d i a g n o s i s . A new imaging t e c h n o -l o g y , n u c l e a r magnetic resonance (NMR), i s c a p a b l e of p r o v i d i n g m o r p h o l o g i c a l i n f o r m a t i o n , 57 as w e l l as i n f o r m a t i o n on c e l l u l a r m e t a b o l i s m . Thus, the a l l o c a t i o n of r e s o u r c e s f o r NMR r e s e a r c h and development w i l l d i v e r t e f f o r t s and r e o s u r c e s away from f u r t h e r r e s e a r c h i n CT t e c h -58 n o l o g y . 90 4. Development of e f f e c t i v e t h e r a p i e s f o r c o n d i -t i o n s d e t e c t a b l e by CT. Such o c c u r r e n c e s would, no doubt, encourage the use of CT as a s c r e e n i n g p r o c e d u r e . 5. The i n f l u e n c e of s o c i o - e c o n o m i c c o n d i t i o n s which a f f e c t p o l i c i e s on h e a l t h c a r e and on the a l l o c a t i o n of r e s o u r c e s . The c o m b i n a t i o n of the l a c k of p r e c i s i o n i n m e d i c a l d e c i s i o n making and the c o n c e r n (which tends to be s u b j e c t i v e and p a t e r n a l i s t i c ) f o r the i n d i v i d u a l p a t i e n t s o f t e n d r i v e s d e c i s i o n making by p h y s i c i a n s toward p r o v i d i n g more r a t h e r than l e s s . Most of them have been o v e r l y charmed by the c l i n i c a l l a b o r a t o r i e s , w i t h d e c r e a -s i n g i m p o r t a n c e p l a c e d on b e d s i d e s k i l l s and c l i n i c a l r e a s o n i n g . The magnitude of t h i s problem i s f u r t h e r i n c r e a s e d by economic and l e g a l i n c e n t i v e s to r e l y more and more on l a b o r a t o r y d i a g n o s t i c a i d e s . To remedy t h i s , p h y s i c i a n s s h o u l d be more aware of c o s t - e f f e c t i v e n e s s and be j u d i c i o u s i n t h e i r s e l e c t i o n of d i a g n o s t i c t e s t s and t h e r a p e u t i c i n t e r v e n t i o n s . R a t i o n a l approaches must be adopted to p r e v e n t a p a t i e n t w i t h a g i v e n s e t of symptoms and s i g n s from b e i n g exposed to an a r r a y of t e s t s t h a t are no l o n g e r a p p l i c a b l e . I t i s n e c e s s a r y to develop new s e t s of a l g o r i t h m s t h a t are f l e x i b l e , r e l a t e d to c l i n i c a l mani-91 f e s t a t i o n s , t o the i n s t i t u t i o n , and t o l o c a l l y a v a i l a b l e equipment and manpower. M e d i c a l t e c h n o l o g i e s a re o f t e n a c c e p t e d f o r c l i n i c a l use w i t h o u t proper e v a l u a t i o n s . Some are u t i l i z e d f o r c o n d i t i o n s beyond those covered by p r e v i o u s e v a l u a t i v e s t u d i e s , w h i l e o t h e r s a re used a t f r e q u e n c i e s beyond those 59 known to be e f f i c a c i o u s and n e c e s s a r y . Even f o r those t e c h n o l o g i e s which a v o i d the above, t h e r e a re s i t u a t i o n s when an e q u a l l y e f f e c t i v e but cheaper a l t e r n a t i v e i s 12 a v a i l a b l e but not used. C o n s e q u e n t l y , e n s u r i n g appro-p r i a t e d i f f u s i o n and a p p r o p r i a t e u t i l i z a t i o n s h o u l d be the two main p o l i c y g o a l s . We s h o u l d l e a r n from our e x p e r i e n c e s w i t h the development, d i f f u s i o n and u t i l i -z a t i o n of CT and be a b l e t o f o r m u l a t e a p p r o p r i a t e and e f f e c t i v e p o l i c i e s t h a t w i l l guide the f u t u r e development of s i m i l a r m e d i c a l t e c h n o l g i e s . For example, a new emerging t e c h n o l o g y i s NMR which, i n many ways, can be compared t o CT. They are both h i g h l y t e c h n i c a l and e x p e n s i v e , but yet are r e l a t i v e l y s a f e and n o n - i n t r u s i v e . NMR equipment employs s u p e r c o n d u c t i v e magnets and r a d i o -waves to r e v e a l d e t a i l e d t i s s u e i n f o r m a t i o n about the 57 body's anatomy and even c h e m i c a l c o m p o s i t i o n . S i m i l a r to CT, t h i s i n f o r m a t i o n i s pr o c e s s e d by a- computer. Al t h o u g h NMR has u t i l i z e d a c o n s i d e r a b l e amount of image p r o c e s s i n g hardware and s o f t w a r e t h a t were developed f o r 92 CT, a l o t of i t s technology has to be newly developed. NMR i s most useful in examinations of the central nervous system, especially in areas where bone artefacts are a problem for CT but not for NMR, because bones do not give 57 off any NMR signals. However, NMR i s more expensive than 58 CT. Evens estimated that the economic break-even charge for NMR would be between US$402 and $775 per patient procedure (depending on volume), compared with $342 for CT. Consequently, we need to c a r e f u l l y evaluate NMR i n terms of the "combined model" of evaluation as proposed in Section 2.3. Namely we should assess the technical c a p a b i l i t y and safety, diagnostic accuracy, diagnostic impact, therapeutic impact, patient outcome, and economic impact of NMR before i t i s allowed to p r o l i f e r a t e . It i s hoped that experiences learned from CT could be applied e f f e c t i v e l y to guide the development and d i f f u s i o n of NMR and other new technologies. 93 REFERENCES 1. Banta, D a v i d . CT: Cost containment m i s d i r e c t e d . AJPH, 1980, 70:215-216. 2. Evans, Roger W. H e a l t h c a r e t e c h n o l o g y and the i n e v i t a b i l i t y of r e s o u r c e a l l o c a t i o n and r a t i o n i n g d e c i s i o n s , p a r t 1. JAMA, 1983, 249:2047-2053. 3. S t o c k i n g , B a r b a r a and M o r r i s o n , S t u a r t , The Image and  the R e a l i t y , O x f o r d : Oxford U n i v e r s i t y P r e s s , 1978. 4. K r e l l , L. Computed tomography updated. P r a c t i t i o n e r , 1984, 228:941-949. 5. 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O b s t e t .  G y n e c o l . Survey, 1979, 34:627-642. 22. Roht, L. H., Selwyn, B. J . , H o l g u i n , A. H., and C h r i s t e n s e n , B. L. P r i n c i p l e s of E p i d e m i o l o g y : _A S e l f - T e a c h i n g Guide, New York: Academic P r e s s , 1982. 23. I n s t i t u t e of M e d i c i n e , N a t i o n a l Academy of S c i e n c e s , Computed Tomography Sc a n n i n g : A P o l i c y Statement, Washington, D.C, 1977. 95 24. G l e n , W i l l i a m , e t a l . The u l t i m a t e CT image. In L i t t l e t o n , J e s s e and D u r i z c h , Mary Lou ( e d s ) , S e c t i o n a l Imaging Methods: A Comparison. B a l t i m o r e : U n i v e r s i t y Park P r e s s , 1983. 25. W i t t e n b e r g , J a c k . Computed tomography of the body, p a r t I . New England J o u r n a l of M e d i c i n e , 1983, 309: 1160-1224. 26. Evens, Ronald G. and J o s t , R. G i l b e r t . Computed tomo-graphy u t i l i z a t i o n and charges i n 1981. R a d i o l o g y , 1982, 145:427-429. 27. T e r - P o g o s s i a n , M.M. P h y s i c a l p r i n c i p l e s and i n s t r u -m e n t a t i o n s . In Lee, L.K., S a g e l , S.S. and S t a n l e y , R.J. ( e d s ) , Computed Body Tomography, New York: Raven P r e s s , 1983. 28. F i n e b e r g , Harvey V. A s s e s s i n g the d i a g n o s t i c c o n t r i -b u t i o n of imaging t e s t s : computed tomography and u l t r a s o u n d of the p a n c r e a s . I n A l p e r o v i t c h , A., de Domel, F.T. and Gremy, F. ( e d s ) , E v a l u a t i o n and E f f i - cacy of M e d i c a l A c t i o n , Amsterdam: N o r t h H o l l a n d P u b l i s h i n g Company, 1979. 29. Graves, E . J . N a t i o n a l Center f o r H e a l t h S t a t i s t i c s , CAT scan use i n s h o r t - s t a y n o n - f e d e r a l h o s p i t a l s : U n i t e d S t a t e s 1979-82. 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U n i t e d S t a t e s , Bureau of the Census, S t a t i s t i c a l  A b s t r a c t of the U n i t e d S t a t e s , (105 e d ) , Washington, D.C, 1984. 96 35. Evans, Robert G. The f i s c a l management of m e d i c a l t e c h n o l o g y : the case of Canada. In Resources f o r  H e a l t h : Technology Assessment f o r P o l i c y Making, B a n t a , David ( e d ) , New York: P r a e g e r P u b l i s h e r s , 1982. 36. Baker, H i l l e r L. The impact of CT on n e u r o r a d i o l o g i c p r a c t i c e . R a d i o l o g y , 1975, 116:637-640. 37. Knaus, W i l l i a m A., S c h r o e d e r , Steven A. and D a v i s , David 0. Impact of new t e c h n o l o g y : the CT s c a n n e r . M e d i c a l C a r e , 1977, 15:533-542. 38. F i n e b e r g , Harvey V., Bauman, Roger and Sosman, Martha. Computerized c r a n i a l tomography: e f f e c t on d i a g n o s t i c and t h e r a p e u t i c p l a n s . JAMA, 1977, 238:224-227. 39. Enlow, Ronald A., et a l . 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( e d s ) , E v a l u a t i o n of E f f i c a c y of M e d i c a l A c t i o n . Amsterdam: N o r t h H o l l a n d P u b l i s h i n g Company, 1979. 44. B.C. M i n i s t r y of H e a l t h , H o s p i t a l Programs, S t a t i s - t i c s of H o s p i t a l Cases D i s c h a r g e d D u r i n g 1980/1 and  1981/2. 45. Anderson, T.W. and S c l o v e , S t a n l e y L. An I n t r o d u c t i o n  to the S t a t i s t i c a l A n a l y s i s of Data. B o s t o n : Houghton M i f f l i n Company, 1978. 46. Winer, B . J . S t a t i s t i c a l P r i n c i p l e s i n E x p e r i m e n t a l  D e s i g n . New York: McGraw H i l l I n c . , 1962. 97 47. N e t e r , John and Wasserman, W i l l i a m . A p p l i e d L i n e a r  S t a t i s t i c a l Models: R e g r e s s i o n , A n a l y s i s of V a r i a n c e , and E x p e r i m e n t a l D e s i g n s . Homewood: R i c h a r d D. I r w i n I n c . , 1974. 48. Bradac, G.B. and Okerson, R. 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R a d i o l o g y . 1981 , 1 3 6 : 5 3 7 - 5 4 2 . 99 APPENDIX A: CALCULATION OF SAMPLE SIZE The sample s i z e i s c a l c u l a t e d u s i n g the f o l l o w i n g 45-47 f o r m u l a : Sample S i z e n = ( 1 . ( C j 7 p i ( l - p A ) + Z(i-p)/p£ ( l - p 2 ) J ( P j - P 2 ) The v a r i a b l e s a re s e t as f o l l o w : U s i n g the c o n v e n t i o n a l v a l u e s f o r «C and jB i n a one-t a i l e d t e s t , s e t *C = 0.05 and J5 = 0.2. 37 Based on data from the GWUMC st u d y , where 45% of the c e r e b r o v a s c u l a r d i s e a s e p a t i e n t s were exposed to c e r e b r a l angiography i n the pre-CT p e r i o d , s e t p 1 = 0.45. I f we w i s h the study to have the power to d e t e c t a change of a p p r o x i m a t e l y 25% i n the post-CT p e r i o d , s e t p^ = 0.35. T h e r e f o r e , n = |l. 645„/0 .45x0 . 55~ + 0. 845/0 . 35x0 . 65 J 2 ( 0 . 1 ) ~ 2 = {0.818 + 0.403}(0.1) ~ 2 = 149 100 APPENDIX B : PATIENT CHART EXTRACT FORM. 1. P a t i e n t I . D . : _ 1 6 2 . Sex : 1 = Male 2 = Female 7 _ 3 . Age ( y e a r s ) : 8 9 4 . Date of A d m i s s i o n 10_ _ _ _ _ _ _ _15 d mo y r 5 . Most r e s p o n s i b l e d i a g n o s i s ( I C D - 9 ) : On Admiss ion :__ 16 _ _ _ _ _ 19 On D i s p o s i t i o n : 20 _ 23 6 . L e n g t h of S tay ( d a y s ) : 24 26 ( C a l c u l a t e d from da te of n e u r o l o g i c a l d i a g n o s i s ) 7 . D i s p o s i t i o n : 1 = D i s c h a r g e 2 = Dea th 27 _ 8. A r e a of R e s i d e n c e : 28 _ 1 = N o r t h Shore 2 = G r e a t e r Vancouver e x c l . N o r t h Shore 3 = O t h e r s 4 = Unknown 9 . S p e c i a l i t y of Most R e s p o n s i b l e P h y s i c i a n : 29 _ 1 = F a m i l y P r a c t i t i o n e r 2 = I n t e r n i s t 3 = G e n e r a l Surgeon 4 = N e u r o l o g i s t 5 = Neurosu rgeon 6 = O t h e r s 10 . N e u r o l o g i c a l T e s t s : 0 = n i l ; 1 t o 8 = number of t e s t s done; 9 = unknown EEG SKULL ARTERIAL PNEUMO NUCLEAR EX CT SURG X-RAY STUDY SCAN CRANIO SCAN TREAT BIOPSY -MENT B e f o r e _ _ _ _ _ _ _ _ Admiss 30 37 D u r i n g _ _ _ _ _ _ _ _ _ H o s p ' n 38 45 1 1 . D i s e a s e G r o u p i n g : 46 _ 1 = B r a i n Tumour 2 = C e r e b r o v a s c u l a r d i s e a s e 12 . Time P e r i o d : 47 _ 1 = 1973 2 = 1977 3 = 1981/2 4 = 1983/4 101 

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