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UBC Theses and Dissertations

An analysis of the relationship between injury severity and hospital inpatient costs Butt, Thomas Stephen


A sample of motor vehicle accident victims hospitalized at Vancouver General Hospital, Vancouver, British Columbia, was chosen to analyze the relationship between hospital costs and the severity of the patient's injury or illness. Severity was measured using two scales, specifically, the Injury Severity Scale and the Abbreviated Injury Scale. Hospital costs were also measured, using two different methodologies. The first was the Per Diem costs that were derived by dividing all related annual costs by the number of patient separation days in 1975. A Per Diem episodic cost was determined by multiplying length of stay by the daily average cost. The second approach used a step-down technique that distributed all non-patient care related hospital services across direct patient care departments, cost centres or programs. Unit costs were then developed for each cost centre, depending upon their annual workload. The 1975 medical record for each patient in the sample was analyzed to determine the number of work units used in each cost centre during the patient's hospital stay. A Step-Down episodic cost was determined by totalling all costs from each cost centre that provided services to the patient. A paired t-Test did not show a significant difference between the Per Diem and Step-Down episodic costs. It was assumed that the range of severity of the patient in the sample weakened this t-Test, severity measured by I.S.S. was grouped in low, medium, and high categories, or when severity was measured by A.I.S., the paired t-Test did show that there was a significant difference in the two costing methodologies. The regression analysis identified a significant relationship between both episodic costs and severity. The strongest relationship occurred when severity was measured by I.S.S. and costs were determined, using the Step-Down methodology (R² = 0.26, F = 35.45). When other related independent variables (i.e., death as outcome and operation not performed) and all interaction terms were introduced, the regression co-efficient increased to R² = 0.45 and the F value increased to F = 24.9. Recommendations were made to include a severity rating on all hospitalized patients' records to assist in patient classification. A final outcome of this study was identifying the value of a Step-Down approach to determining hospital costs and identifying the limitations of the Per Diem methodology of hospital accounting.

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