CORONARY-ARTERY BYPASS-GRAFTING IN CANADA - NATIONAL AND PROVINCIAL MORTALITY TRENDS, 1992-1995

Background: Despite a body of research on outcomes of coronary artery bypass grafting (CABG) in Canada, little is known about Canada-wide ou tcome trends and interregional differences in outcome. The objectives of this study were to examine Canadian trends in rates of in-hospital death after CABG and to compare provincial risk-adjusted death rates. Methods: Hospital discharge data were obtained from the Canadian Insti tute for Health information and were used to identify complete cohorts of patients who underwent CABG in 8 provinces in fiscal years 1992/93 through 1995/96. Data from Quebec hospitals were not available. A log istic regression model was used to calculate risk-adjusted death rates by year, province, and province and year. Results: A total of 50 357 CABG cases were studied, with an overall death rate of 3.6%. A nationa l trend of decreasing mortality was found, with a risk-adjusted death rate of 3.8% in 1992/93 versus 3.2% in 1995/96 (relative decrease of 1 7%) (p < 0.001 for difference across years). Some provinces (e.g., Alb erta, Manitoba and Ontario) achieved overall declines in death rates o ver the study period, whereas others (e.g., British Columbia and Saska tchewan) did not. The average severity of illness of patients who unde rwent CABG differed considerably across provinces. Despite risk adjust ment for these differences, provincial death rates varied significantl y (p < 0.001). Interpretation: Rates of death after CABG in Canada dec reased significantly in a relatively short period. Despite this encour aging finding, there were interprovincial differences in severity of i llness and risk-adjusted death rates. This finding raises the possibil ity of unequal access to CABG and variable quality of care for patient s undergoing the surgery across Canadian provinces.