Sex differences in outcomes after coronary artery bypass grafting: A pooled analysis of individual patient data

Aims: Data suggest that women have worse outcomes than men after coronary artery bypass grafting (CABG), but results have been inconsistent across studies. Due to the large differences in baseline characteristics between sexes, suboptimal risk adjustment due to low-quality data may be the reason for the observed differences. To overcome this limitation, we undertook a systematic review and pooled analysis of high-quality individual patient data from large CABG trials to compare the adjusted outcomes of women and men. Methods and results: The primary outcome was a composite of all-cause mortality, myocardial infarction (MI), stroke, and repeat revascularization (major adverse cardiac and cerebrovascular events, MACCE). The secondary outcome was all-cause mortality. Multivariable mixed-effect Cox regression was used. Four trials involving 13 193 patients (10 479 males; 2714 females) were included. Over 5 years of follow-up, women had a significantly higher risk of MACCE [adjusted hazard ratio (HR) 1.12, 95% confidence interval (CI) 1.04-1.21; P = 0.004] but similar mortality (adjusted HR 1.03, 95% CI 0.94-1.14; P = 0.51) compared to men. Women had higher incidence of MI (adjusted HR 1.30, 95% CI 1.11-1.52) and repeat revascularization (adjusted HR 1.22, 95% CI 1.04-1.43) but not stroke (adjusted HR 1.17, 95% CI 0.90-1.52). The difference in MACCE between sexes was not significant in patients 75 years and older. The use of off-pump surgery and multiple arterial grafting did not modify the difference between sexes. Conclusions: Women have worse outcomes than men in the first 5 years after CABG. This difference is not significant in patients aged over 75 years and is not affected by the surgical technique.