Outcomes after coronary artery bypass graft surgery in Canada: 1992/93 to 2000/01

Background — The authors have previously reported on Canada-wide outcomes of coronary artery bypass graft (CABG) surgery for 1992/93 through 1995/96.

Objective — To provide an updated Canada-wide CABG surgery outcome report with outcome data organized by province and by year for 1992/93 through 2000/01.

Methods — Hospital discharge abstract data were obtained from the Canadian Institute for Health Information and were used to identify all patients who underwent isolated CABG surgery in eight provinces from fiscal year 1992/93 through 2000/01. Crude data from Quebec hospitals were available for calendar years 1998 and 1999. Logistic regression modelling was used to calculate risk-adjusted in-hospital mortality rates by year and province.

Results — Patients undergoing CABG surgery in the later years studied were on average older and had more comorbidities than did patients undergoing this surgery in earlier years. Despite increasing case complexity, risk-adjusted mortality rates decreased significantly from 3.5% (95% CI 3.2% to 3.8%) to 2.0% (95% CI 1.8% to 2.3%). Risk-adjusted mortality rates varied between provinces. Provincial risk-adjusted mortality rates ranged from 2.0% to 3.3%. However, all provinces studied had either persistently low mortality rates (Nova Scotia) or declining mortality rates across years studied, such that all provinces achieved risk-adjusted mortality rates of 2.7% or lower in 2000/01.

Conclusions — This evaluation of Canadian CABG surgery outcomes demonstrates a pattern of either steadily improving or persistently favourable provincial in-hospital mortality rates after isolated CABG surgery. These favourable provincial outcome trends have been achieved despite an accompanying increase in the average case complexity of patients undergoing CABG in Canada.