Sex differences in mortality after first time, isolated coronary artery bypass graft surgery: a systematic review and meta-analysis of randomized controlled trials

Aim Reports of sex-specific differences in mortality after coronary artery bypass graft surgery (CABGS) are contradictory. The review aim was to determine whether CABGS is differentially efficacious than alternative procedures by sex, on short- and longer-term mortality. Methods and results EMBASE, CINAHL, Medline, and the Cochrane Library were searched. Inclusion criteria: English language, randomized controlled trials from 2010, comparing isolated CABGS to alternative revascularization. Analyses were included Mantel-Haenszel fixed-effects modelling, risk of bias (Cochrane RoB2), and quality assessment (CONSORT). PROSPERO Registration ID: CRD42020181673. The search yielded 4459 citations, and full-text review of 29 articles revealed nine studies for inclusion with variable time to follow-up. Risk of mortality for women was similar in pooled analyses [risk ratio (RR) 0.94, 95% confidence interval (CI) 0.84-1.05, P = 0.26] but higher in sensitivity analyses excluding 'high risk' patients (RR 1.22, 95% CI 1.01-1.48, P = 0.04). At 30 days and 10 years, in contrast to men, women had an 18% (RR 0.82, 95% CI 0.66-1.02, P = 0.08) and 19% (RR 0.81, 95% CI 0.69-0.95, P = 0.01) mortality risk reduction. At 1-2 years women had a 7% (RR 1.07, 95% CI 0.69-1.64, P = 0.77), and at 2-5 years a 25% increase in risk of mortality compared with men (RR 1.25, 95% CI 1.03-1.53, P = 0.03). Women were increasingly under-represented over time comprising 41% (30 days) to 16.7% (10 years) of the pooled population. Conclusion Meta-analysis revealed inconsistent sex-specific differences in mortality after CABGS. Trials with sex-specific stratification are required to ensure appropriate sex-differentiated treatments for revascularization.