Time-related mortality for women after coronary artery bypass graft surgery: a population-based study

Objective — This study explores the relative early and late mortality risks in women and men after coronary artery bypass graft surgery.

Methods — This was a retrospective cohort study (n = 54,425 patients, 12,079 women) using clinical data for all patients who underwent isolated coronary artery bypass graft surgery in Ontario between fiscal years 1991 and 1999 obtained from the Cardiac Care Network database, with outcomes of early (≤1 year) and late (>1 year up to 10 years) interval mortality identified through linkage to administrative databases.

Results — Female surgical candidates were older (65 vs 62 years, P < .0001) and higher-risk patients. The risk-adjusted survival of female patients was worse than that of male patients in the first year after coronary artery bypass graft surgery, but their long-term mortality was similar to that of male patients. The Cox proportional hazards model for early mortality had an adjusted female hazard ratio of 1.44 (95% confidence interval, 1.29-1.61; P = .02). This significantly differed from the late mortality model, which had a hazard ratio of 0.89 (95% confidence interval, 0.78-1.0; P = .06).

Conclusions — Early mortality was significantly higher for women after coronary artery bypass graft surgery, despite adjustment for confounding factors. However, the long-term relative mortality risk for women appeared equivalent to or even better than that experienced by men as early as 1 year after coronary artery bypass graft surgery. This population-based study of long-term mortality supports the benefits of coronary artery bypass graft surgery for women in the current era. However, further research is needed to identify ways to reduce early postoperative mortality in women.