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Do women spend longer on wait lists for coronary bypass surgery? Analysis of a population-based registry… Levy, Adrian R; Sobolev, Boris G; Kuramoto, Lisa; Hayden, Robert; MacLeod, Stuart M Aug 2, 2007

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ralssBioMed CentBMC Cardiovascular DisordersOpen AcceResearch articleDo women spend longer on wait lists for coronary bypass surgery? Analysis of a population-based registry in British Columbia, CanadaAdrian R Levy*†1,2, Boris G Sobolev†1,3, Lisa Kuramoto3, Robert Hayden4,5 and Stuart M MacLeod6,7Address: 1Department of Health Care and Epidemiology, University of British Columbia (BC), Vancouver, Canada, 2Centre for Health Evaluation & Outcome Sciences, Providence Health Care, Vancouver, Canada, 3Centre for Clinical Epidemiology and Evaluation, Vancouver General Hospital, Vancouver, Canada, 4Department of Surgery, Royal Columbian Hospital, New Westminster, Canada, 5BC Cardiac Registries, Provincial Health Services Authority, Vancouver, Canada, 6BC Research Institute of Women's and Children's Health, Vancouver, BC, Canada and 7BC Provincial Health Services Authority, Vancouver, CanadaEmail: Adrian R Levy* - alevy@cheos.ubc.ca; Boris G Sobolev - sobolev@interchange.ubc.ca; Lisa Kuramoto - Lisa.Kuramoto@vch.ca; Robert Hayden - erh@telus.net; Stuart M MacLeod - smacleod@cw.bc.ca* Corresponding author    †Equal contributorsAbstractBackground: Studies have shown patients who are delayed for surgical cardiac revascularizationare faced with increased risks of symptom deterioration and death. This could explain theobservation that operative mortality among persons undergoing coronary artery bypass surgery(CABG) is higher among women than men. However, in jurisdictions that employ priority wait liststo manage access to elective cardiac surgery, there is little information on whether women waitlonger than men for CABG. It is therefore difficult to ascertain whether higher operative mortalityamong women is due to biological differences or to delayed access to elective CABG.Methods: Using records from a population-based registry, we compared the wait-list timebetween women and men in British Columbia (BC) between 1990 and 2000. We compared thenumber of weeks from registration to surgery for equal proportions of women and men, afteradjusting for priority, comorbidity and age.Results: In BC in the 1990s, 9,167 patients aged 40 years and over were registered on wait listsfor CABG and spent a total of 136,071 person-weeks waiting. At the time of registration for CABG,women were more likely to have a comorbid condition than men. We found little evidence tosuggest that women waited longer than men for CABG after registration, after adjusting forcomorbidity and age, either overall or within three priority groups.Conclusion: Our findings support the hypothesis that higher operative mortality during electiveCABG operations observed among women is not due to longer delays for the procedure.BackgroundIn publicly funded health care systems, priority wait listsvention is designed to facilitate access to surgery within aclinically appropriate time [2], patients who are delayedPublished: 2 August 2007BMC Cardiovascular Disorders 2007, 7:24 doi:10.1186/1471-2261-7-24Received: 10 January 2007Accepted: 2 August 2007This article is available from: http://www.biomedcentral.com/1471-2261/7/24© 2007 Levy et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Page 1 of 8(page number not for citation purposes)are commonly used to manage access to elective cardiacsurgery [1]. While queuing according to urgency of inter-for surgical cardiac revascularization are faced withincreased risks of worsening symptoms [3] and deathBMC Cardiovascular Disorders 2007, 7:24 http://www.biomedcentral.com/1471-2261/7/24[4,5]. The additional risks incurred by longer delays maybe of particular concern for women with cardiovasculardisease because, at presentation, women are more likelythan men to have comorbid medical conditions such ashypertension, diabetes or obesity [6-11]. These comorbidmedical conditions may increase the amount of time thatwomen wait for CABG.A number of studies have shown that the operative mor-tality among women undergoing CABG surgery is higherthan that of men [12,13]. However, there is no informa-tion on whether women wait longer than men for CABG,after adjusting for age, severity of disease and comorbid-ity. It is therefore difficult to ascertain whether higheroperative mortality may be due to delayed access to carein the pre-surgical period. Addressing this question isimportant for improving the care of persons with cardio-vascular disease because, if differences are due to longerwaiting times, it might be feasible to implement strategiesto reduce waiting times among women.The objective of this study was to compare the time fromregistration on the wait list to CABG between women andmen, after adjusting for differences in age, severity of cor-onary artery disease, and comorbidity. To examine theconsistency over time of any effects of sex on waitingtimes, comparisons were done across synthetic cohorts ofpatients defined by two-year periods of registration on thewait lists: 1991–92, 1993–94, 1995–96, 1997–98, or1999–2000.MethodsData sourcesThe BC Cardiac Registries (BCCR) prospectively capturethe occurrence and timing of registration, surgery, orremoval from the wait lists without surgery, for allpatients accepted for cardiac surgery procedures in thefour heart-surgery centers delivering services in BC (popu-lation of four million) [14]. Registered patients wereremoved from the wait lists without surgery if they died,declined the operation, accepted surgery from anothersurgeon, moved away, or continued with medical man-agement. Cardiac surgeons in BC have developed com-mon guidelines for prioritizing patients and assigning thesuggested waiting time for surgery based on angina symp-toms, affected coronary anatomy, non-invasive testresults, and left ventricular function impairment asdescribed elsewhere [15]. Using those guidelines, eachpatient was classified by the surgeon into one of the fol-lowing three groups: priority 1 if the suggested time to sur-gery was three days, priority 2 if the suggested time toTable 1: Characteristics of 9,167 patients registered for CABG surgery in British Columbia, 1991–2000Women (N = 1,629) Men (N = 7,538)Characteristic N (%) N (%)Age Group (y)40–49 68 (4.2) 600 (8.0)50–59 241 (14.8) 1764 (23.4)60–69 638 (39.2) 2892 (38.4)70–79 633 (38.9) 2137 (28.3)80–89 49 (3.0) 145 (1.9)Urgency at RegistrationPriority 1 123 (7.6) 534 (7.1)Priority 2 1116 (68.5) 5339 (70.8)Priority 3 377 (23.1) 1567 (20.8)Unknown 13 (0.8) 98 (1.3)Comorbidity at RegistrationNo comorbidity 750 (46.0) 3985 (52.9)Major comorbidity (CHF, diabetes, COPD, rheumatism, cancer)463 (28.4) 1540 (20.4)Other conditions 416 (25.2) 2013 (26.7)Registration Period1991–1992 318 (19.5) 1394 (18.5)1993–1994 297 (18.2) 1574 (20.9)1995–1996 379 (23.3) 1619 (21.5)1997–1998 350 (21.5) 1527 (20.3)1999–2000 285 (17.5) 1424 (18.9)Page 2 of 8(page number not for citation purposes)Abbreviations: CABG = outpatient isolated coronary artery bypass surgery; CHF = congestive heart failure; COPD = chronic obstructive pulmonary diseaseBMC Cardiovascular Disorders 2007, 7:24 http://www.biomedcentral.com/1471-2261/7/24surgery was six weeks, and priority 3 if the suggested timeto surgery was 12 weeks.PatientsThere were 9,366 records of registration for isolated CABGadded to the Registry between January 1991 and Decem-ber 2000. We excluded 135 records of patients who were:emergency cases (30), removed on the registration date(101), and had missing operating room reports (4). Allremaining 9,231 records had either the surgery date or thedate and reason of removal from the list without surgery.We restricted the analyses to the first 52 weeks after regis-tration so that 475 (5%) patients remaining on the lists at12 months were censored. Of those, 167 eventuallyunderwent surgery; seven died; 78 received medical treat-ment; 104 declined surgery; 17 were transferred toanother surgeon or hospital; and 102 were removed forother reasons.ComorbidityTo control for co-existing conditions, each patient wasclassified as (1) presenting with no co-existing conditions,(2) presenting with a major comorbid condition includ-ing congestive heart failure, diabetes, chronic obstructivepulmonary disease, cancer, or rheumatoid arthritis, or (3)presenting with a minor comorbid condition includingother coexisting chronic conditions including peripheralvascular disease, cerebrovascular disease, dementia, pepticulcer disease, hemiplegia, renal disease, or liver disease[16]. The first set of conditions were those originally usedpotential concomitant illnesses that could delay surgery,we added the other category that included conditionsfrom Charlson comorbidity index [18]. We entered twoindicator variables in the models to represent the threecomorbidity categories.Statistical methodsWaiting times were analyzed as prospective observationsbeginning at the time of registration. Each patient had awaiting time calculated in calendar weeks from registra-tion to surgery or removal for other reasons. The cumula-tive probability of undergoing surgery as a function ofwaiting time was estimated using the Kaplan-Meiermethod [19]. Patients removed from the list for reasonsother than surgery were treated as censored observations.Primary comparisons were done across synthetic cohortsof patients defined by two-year periods of registration onthe wait lists. Within each registration period, differencesin the distributions of wait-list times between women andmen were examined using the log rank-test [20].The effect size for each period was estimated using hazardratios for surgery derived from a Cox proportional hazardsmodel [21] in which we stratified on age. The prioritygroup and the comorbidity measures were included asindependent variables in the Cox model to estimateadjusted effects. Hazard ratios (HR) for women evaluatethe conditional probability of undergoing CABG relativeto men at any week on the list. The weekly surgery rate wasTable 2: Outcomes of registration for CABG surgery in British Columbia 1991–2000 at 52 weeksWomen (N = 1629) Men (N = 7538)Outcomes N (%) N (%)Underwent Surgery*Within recommended time 534 (32.8) 2393 (31.7)Beyond recommended time845 (51.9) 4120 (54.7)Between 1 and 12 weeks, priority unknown8 (0.5) 33 (0.4)Removed without surgery**Died while waiting 9 (0.6) 81 (1.1)Medical treatment 46 (2.8) 128 (1.7)Patient request 42 (2.6) 145 (1.9)Transferred or moved 12 (0.7) 87 (1.2)Other reason 45 (2.8) 166 (2.2)Still on wait list at 52 weeks88 (5.4) 385 (5.1)Abbreviation: CABG = outpatient isolated coronary artery bypass surgery* χ2 = 2.0, df = 2, p = 0.36** χ2 = 14.8, df = 4, p = 0.0052Page 3 of 8(page number not for citation purposes)in a study on the appropriateness of coronary revasculari-zation [17]. As we were concerned that there were othercalculated by dividing the number of operations by thetotal number of patient-weeks on the list.BMC Cardiovascular Disorders 2007, 7:24 http://www.biomedcentral.com/1471-2261/7/24The Clinical Research Ethics Board of the University ofBritish Columbia approved the study protocol in Septem-ber, 2001. Individual consent was waived.Results and discussionIn BC in the 1990s, 9,167 patients aged 40 years and overwere registered on wait lists for CABG and spent a total of136,071 person-weeks waiting. Of 9,167 persons aged 40to 89 y who were registered for CABG in BC between 1991and 2000, about 18% (1,629) were women (Table 1). Atregistration for CABG, among women, 19% were underage 60 y and 42% were over age 70 y, compared with 31%of men under age 60 y and 30% over age 70 y. There wasa significant difference in the distribution of age betweenwomen and men (X2 = 128.3, df = 4, P < 0.0001). Thenumber of women registered ranged from a low of 297 in1993–1994 to a high of 379 in 1995–1996 (data notshown).At registration, 46% of women had no comorbid condi-tions recorded, 25% had at least one minor comorbidmedical condition and 28% had at least one majorcomorbid condition. Women were 20% less likely thanmen to have no comorbid conditions (OR = 0.8) and 50%more likely to have a major comorbid condition (OR =1.5). There was a significant difference in the distributionof women and men received the operation within the rec-ommended waiting time (Table 2).Over all periods, at registration for CABG, approximatelyequal proportions of women and men were in prioritygroup 1 (OR = 1.0, 95% CI: 0.8, 1.2 (adjusted for year andage)), a lower proportion of women was in priority group2 (OR = 0.9, 95% CI: 0.8, 1.0 (adjusted for year and age)),and a higher proportion was in priority group 3 (OR = 1.2,95% CI 1.0, 1.3 (adjusted for year and age)) (Table 3).There was a significant difference in the distribution ofpriority group among women and men (X2 = 7.72, df = 3,P = 0.0521).Among women, the distribution of priority group at regis-tration for CABG remained approximately constant dur-ing the first four periods; in the final period, there was areduced proportion in priority group 1 and an increasedproportion in the priority group 3. A similar pattern wasobserved among men, with a relatively constant distribu-tion of priority groups during the first four periods and ashift in the last period to a reduced proportion in the mosturgent priority group and an increased proportion in theleast urgent priority group.Among women and over all registration periods, theTable 3: Distribution of patients registered for CABG in British Columbia 1991–2000 by priority group and registration periodPriority 1 Priority 2 Priority 3Registration PeriodN (%) N (%) N (%)Women1991–1992 27 (8.5) 224 (70.4) 65 (20.4)1993–1994 21 (7.1) 210 (70.7) 64 (21.5)1995–1996 47 (12.4) 248 (65.4) 81 (21.4)1997–1998 25 (7.1) 238 (68.0) 83 (23.7)1999–2000 3 (1.1) 196 (68.8) 84 (29.5)All periods* 123 (7.6) 1116 (68.5) 377 (23.1)Men1991–1992 88 (6.3) 990 (71.0) 267 (19.2)1993–1994 89 (5.7) 1160 (73.7) 317 (20.1)1995–1996 202 (12.5) 1105 (68.3) 291 (18.0)1997–1998 91 (6.0) 1083 (70.9) 341 (22.3)1999–2000 64 (4.5) 1001 (70.3) 351 (24.6)All periods** 534 (7.1) 5339 (70.8) 1567 (20.8)Abbreviation: CABG = outpatient isolated coronary artery bypass surgery*Excludes 13 patients with unknown priority**Excludes 98 patients with unknown priorityPage 4 of 8(page number not for citation purposes)of comorbid medical conditions between women andmen (X2 = 51.9, df = 2, P < 0.0001). A similar proportionmedian wait list time for outpatient isolated CABG in BCwas 11 weeks, ranging from 7 weeks in the earliest periodBMC Cardiovascular Disorders 2007, 7:24 http://www.biomedcentral.com/1471-2261/7/24to 16 weeks in the middle period (Table 4). Among men and over all registration periods, the median wait list timewas also 11 weeks, ranging from 9 weeks in the earliestperiod to 14 weeks in the middle period. As measured bythe interquartile range (IQR), the variability in wait listtime over all periods was 1 week longer for women thanmen (18 weeks versus 17 weeks).One difference between women and men was observedfor those patients with longer waiting times: the wait-listinterval requiring 40% of operations in patients stayingon the lists longer than the median time was 6 weekslonger among women than men, as measured by the dif-ferences between 90th and 50th percentiles. The differentialbetween women and men reached a maximum 14 weeksin 1993–1994.The differences in time spent on the wait lists were not sig-nificantly different between women and men in any cal-endar period of registration (P > 0.10 for all periods). Thedistributions of the estimated probability of undergoingCABG at each week on the wait list for the period 1999–2000 were overlapping for women and men over the first36 weeks after registration (Figure 1).For women, the average weekly rate of operations per 100varied from 6.9 (6.1–7.7) in the 1991–1992 cohort to 4.7(4.2–5.2) in the 1995–1996 cohort to 5.8 (5.1–6.6) in theCharacteristics of 9,167 patients registered for outpatient isolated coronary artery bypass sur ery in British Columbia, 1991–2000Figure 1Characteristics of 9,167 patients registered for outpatient isolated coronary artery bypass surgery in British Columbia, <1 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 3600.  TIME (WEEKS)PROBABILITY  OF  UNDERGOING  SURGERYTable 4: Percentiles of wait-list time (weeks) for women and men registered for CABG in British Columbia 1991–2000 by registration periodPercentileRegistration Period10th 25th 50th 75th 90th 90th – 50thWomen1991–1992 1 2 7 19 43 361993–1994 1 4 8 18 49 411995–1996 1 6 16 27 53 371997–1998 3 6 15 26 40 251999–2000 3 6 11 19 47 36All periods 1 5 11 23 49 38Men1991–1992 1 3 9 19 44 251993–1994 2 4 9 18 44 251995–1996 1 6 14 26 46 321997–1998 2 6 13 24 43 301999–2000 3 6 10 19 39 29All periods 2 5 11 22 43 32Abbreviation: CABG = outpatient isolated coronary artery bypass surgeryPage 5 of 8(page number not for citation purposes)1999–2000 cohort (Table 5). At any week on the list, theconditional probability of undergoing surgery was1991–2000.BMC Cardiovascular Disorders 2007, 7:24 http://www.biomedcentral.com/1471-2261/7/24reduced by 39% in 1995–1996 women, HR = 0.61 (0.51–0.72), and by 13% in 1999–2000 women, HR = 0.87(0.73–1.05), relative to the period 1991–1992, afteradjusting for priority, comorbidity, and age.For men, the average weekly rate of operations per 100varied from 6.5 (6.1–6.8) in the 1991–1992 cohort to 5.1(4.9–5.4) in the 1995–1996 cohort to 6.3 (6.0–6.7) in the1999–2000 cohort. At any week on the list, the condi-tional probability of undergoing surgery was reduced by28% in 1995–1996 men, HR = 0.72 (0.66–0.78), and by7% in 1999–2000 men, HR = 0.93 (0.86–1.01), relative tothe period 1991–1992, after adjusting for priority, comor-bidity, and age.Within priority groups, there was little evidence thatwomen waited longer than men for CABG after registra-tion, after adjusting for comorbidity, age and sex (Table6).ConclusionIn this paper we found little evidence that women waitedlonger than men for elective CABG in BC during the1990s. After adjusting for comorbidity and age, the timespent on CABG wait lists did not differ between womenand men in any calendar period of registration or withinany of the three priority groups. A similar proportion ofThe distribution of women undergoing CABG was lowerthan reported in other jurisdictions [6,8,22,23] andwithin the range reported in other Canadian provinces: alower proportion (12%) of women was observed in NovaScotia [3] and a higher proportion (30%) in Alberta [24].The significance of our findings can be understood withinthe context that women have higher mortality after CABG[6,25-28]. This issue was addressed using the UnitedStates Society of Thoracic Surgeons National Cardiac Sur-gery Database to examine peri-operative survival among344,913 patients undergoing CABG between 1994 and1997 [6]. After adjustment for other risk factors, femalesex remained an independent predictor of operative mor-tality in all but very high risk patients. The main findingin the current study – that waiting times did not differbetween women and men in BC – supports the hypothesisthat the higher operative mortality among women is dueto biological differences. Studies from the ClevelandClinic and the Northern New England Study Group haveshown the impact of body size on peri-operative CABGmortality [29,30]. Women typically have a smaller bodysurface area than men which in turn is associated withsmaller hearts and correspondingly diminutive coronaryarteries. This is thought to increase the technical difficultyof CABG and contribute to poorer outcome [31]. Alterna-tively, the differences in operative mortality may be due toTable 5: Average weekly rate of CABG in British Columbia, 1991–2000 and adjusted hazard ratios by registration periodRegistration PeriodNumber of operationsTotal waiting time, weeksCrude Rate, per 100SE RR 95% CI*Women1991–1992 281 4094.0 6.9 (0.4) 1.00 Referent1993–1994 260 3892.5 6.7 (0.4) 0.98 (0.82, 1.17)1995–1996 313 6676.5 4.7 (0.3) 0.61 (0.51, 0.72)1997–1998 293 5587.5 5.2 (0.3) 0.68 (0.57, 0.81)1999–2000 240 4103.5 5.8 (0.4) 0.87 (0.73, 1.05)Men1991–1992 1211 18773.0 6.5 (0.2) 1.00 Referent1993–1994 1370 21221.0 6.5 (0.2) 1.01 (0.93, 1.09)1995–1996 1403 27353.0 5.1 (0.1) 0.72 (0.66, 0.78)1997–1998 1311 24570.0 5.3 (0.1) 0.79 (0.72, 0.85)1999–2000 1251 19799.5 6.3 (0.2) 0.93 (0.86, 1.01)Abbreviations: CABG = outpatient isolated coronary artery bypass surgery; SE = standard error; HR = hazard ratio; 95% CI = 95% confidence interval*adjusted for priority group and comorbidity; stratified by age.0 patients were on the wait list on December 31, 2001Page 6 of 8(page number not for citation purposes)women and men received the operation within the recom-mended waiting time.a delay in treatment or in referral to catheterization [32].Other Canadian investigators found that the medianBMC Cardiovascular Disorders 2007, 7:24 http://www.biomedcentral.com/1471-2261/7/24duration between cardiac catheterization and surgery diddiffer between women and men waiting for CABG or aor-tic valve replacement in Nova Scotia [3].We also found that, for one portion of the waiting timedistribution that included patients who waited longerthan the median waiting time as measured by the differ-ences between 90th and 50th percentiles, the waiting timewas six weeks longer among women than men. An expla-nation of this finding remains speculative and could serveas the basis of a future study.As reported by other investigators [6-11], we found thatwomen were significantly older and more likely to have amajor comorbid medical conditions when registered forCABG. Part of this difference stems from women present-ing with initial symptoms of cardiovascular disease at anolder age. This may also be indicative of differences inhealth seeking behavior by women [33,34] or in referralpatterns from a cardiologist to a cardiac surgeon forwomen with symptoms of cardiovascular disease [32].LimitationsThe internal validity of this study was high and it isunlikely that potential biases could have materiallyaffected the results. Selection bias was minimized becausethe registry maintains a record for virtually every personassessed by a cardiac surgeon in BC and active follow-upis undertaken for all persons registered. Information biaswas not a concern because there is no reason to believethat any coding or other errors occurred differentiallyamong women and men. While there is always the possi-bility of confounding in an observational study, the like-lihood of a major unknown confounder is small becauseit would need to have exerted a strong influence to sub-stantially affecting the interpretation and results, and weare unaware of any powerful factor that affected waitingtime.The main question regarding the validity of the study isthe generalizability of the results. A study examiningwhether the waiting time for CABG differs betweenbe of considerable interest to determine the impact of sexin health systems that use wait lists but have differenttypes of reimbursement mechanisms.Competing interestsThe author(s) declare that they have no competing inter-ests.Authors' contributionsARL conceived and designed the study, acquired the data,interpreted the results, and drafted the manuscript. BGSconceived and designed the study, analysed the data,interpreted the results, and drafted the manuscript. LKanalysed the data and interpreted the results. RH partici-pated in the design of the study, helped acquire the data,and interpreted the results. SMM conceived and designedthe study and interpreted the results. All authors read andapproved the final manuscript.AcknowledgementsThe authors gratefully acknowledge the contributions of Rita Sobolyeva and Laurie Kilburn.The following cardiac surgeons are contributors to the BCCR Surgical Research Committee: Drs. James Abel, Richard Brownlee, Larry Burr, Anson Cheung, James Dutton, Guy Fradet, Virginia Gudas, Robert Hayden, Eric Jamieson, Michael Janusz, Shahzad Karim, Tim Latham, Jacques LeBlanc, Sam Lichtenstein, Hilton Ling, John Ofiesh, Michael Perchinsky, Peter Skars-gard and Frank Tyers.This study received financial support from the: BC Research Institute of Women's and Children's Health, St Paul's Hospital Foundation (ARL), Van-couver Coastal Health Research Institute (BGS, JMF), Michael Smith Foun-dation for Health Research (ARL), Canada Foundation for Innovation (ARL, BGS), and Canada Research Chairs program (BGS).References1. Hurst J, Siciliani L: Tackling excessive waiting times for electivesurgery: a comparison of policies in twelve OECD countries.Paris, Organisation for Economic Co-operation and Development;2003. 2. MacCormick AD, Collecutt WG, Parry BR: Prioritizing patientsfor elective surgery: a systematic review.  ANZ J Surg 2003,73:633-642.3. Ray AA, Buth KJ, Sullivan JA, Johnstone DE, Hirsch GM: Waiting forcardiac surgery: results of a risk-stratified queuing process.Circulation 2001, 104:I92-I98.Table 6: Rate Ratios* by sex and priority group for patients undergoing CABG in British Columbia 1991–2000Priority 1 Priority 2 Priority 3Sex RR 95% CI RR 95% CI RR 95% CIMen 1.00 Referent 1.00 Referent 1.00 ReferentWomen 0.88 (0.69, 1.14) 0.99 (0.92, 1.06) 1.01 (0.88, 1.16)Abbreviations: CABG = outpatient isolated coronary artery bypass surgery; RR = rate ratio; 95% CI = 95% confidence interval*adjusted for comorbidity; stratified by age and registration periodPage 7 of 8(page number not for citation purposes)women and men in another jurisdiction that employs pri-ority wait lists for CABG would be valuable. It would also4. 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