Outcomes after aortic and mitral valve replacement surgery in Canada: 1994/95 to 1999/2000

Background — Although outcomes after coronary artery bypass grafting (CABG) have been studied extensively across Canada, using both clinical and administrative databases, studies examining outcomes after valve surgery in Canada have been restricted to regional investigations using clinical data sources of limited scope. The objective of the present study was to report on observed and risk-adjusted in-hospital mortality rates after aortic valve replacement (AVR) and mitral valve replacement (MVR) across Canada between 1994/95 and 1999/2000 using administrative data.

Methods — All cases of AVR and MVR (with and without concomitant CABG) performed between 1994/95 and 1999/2000 were identified using hospital discharge abstract data obtained from the Canadian Institute for Health Information. Rates of in-hospital mortality were risk-adjusted using logistic regression modelling techniques to account for variations in sociodemographic, comorbidity, and disease-specific indicators of average severity of illness across years and provinces. Risk-adjusted outcomes were unavailable for the province of Quebec.

Results — The overall in-hospital mortality rate, excluding Quebec, between 1994/95 and 1999/2000 after isolated AVR with or without CABG was 3.7% and isolated MVR with or without CABG was 5.7%. Although risk-adjusted in-hospital mortality rates by year were unchanged between 1994/95 and 1999/2000, significant interprovincial variation did exist, ranging from 2.6% to 6.8% for AVR with or without CABG and 2.5% to 13.0% for MVR with or without CABG.

Conclusion — In-hospital mortality rates after valve surgery have remained stable over time. However, significant variation in outcomes was noted between provinces. The results of this study provide the first comprehensive account of valve surgery outcomes across Canada.