The improving outcomes of coronary artery bypass graft surgery in Ontario, 1981 to 1995

Background — There is continuing uncertainty over the relative contribution of outcomes monitoring to changes in surgical outcomes over time. The authors studied temporal trends in the clinical characteristics and short-term outcomes of patients who underwent coronary artery bypass grafting (CABG) in Ontario before and after the implementation, in 1993, of a province-wide program to provide feedback on cardiac surgery outcomes.

Methods — The authors analysed data from hospital discharge abstracts on the clinical characteristics and in-hospital death rates of all 67,784 patients who underwent isolated CABG in Ontario between Apr. 1, 1981, and Mar. 31, 1996.

Results — Death rates were relatively stable during the first half of the 1980s, then declined gradually in the second half of the decade; this decline continued into the first half of the 1990s. In the 1990s patients were older than those in the 1980s, and a higher proportion had coexisting diseases. Between 1986/87 and 1995/96 the unadjusted death rate decreased by 52% (5.0% v. 2.4%) (p < 0.001). The annual relative rate of decline was approximately 6% (95% confidence interval 5% to 7%) in the period before the outcomes feedback program was implemented and about 9% (95% confidence interval 7% to 11%) in the period after implementation.

Interpretation — Rates of death after CABG have been declining steadily in Ontario since the mid-1980s. Outcomes-based quality improvement interventions may facilitate; but are not a prerequisite for, improvements in the quality of surgical care.