Association between female sex and short-term mortality after coronary artery bypass grafting: a retrospective cohort study

Abstract Background With the changes in coronary artery bypass grafting (CABG) guidelines, the demographic composition of surgical patients and their preoperative baseline characteristics have also shifted. However, it remains unclear whether sex differences affect postoperative mortality rates. Methods Data from the Medical Information Mart for Intensive Care-IV (MIMIC-IV) database, including 3,757 patients who underwent CABG surgery between 2008 and 2019, were retrospectively analyzed. A cohort with a 1:1 sex ratio was generated through propensity score to balance baseline differences between groups. Kaplan-Meier curves estimated the cumulative incidence of 30-day and 1-year postoperative mortality in both groups, with comparisons made using the log-rank test. Cox proportional hazards regression models assessed the association between sex and 30-day and 1-year mortality, reporting hazard ratios (HRs) and 95% confidence intervals (CIs). Stratified analysis and sensitivity testing were conducted on the propensity score-matched (PSM) cohort to validate the findings. Results After matching, each sex group included 713 patients. Kaplan-Meier analysis in both the original and PSM cohorts showed higher 1-year postoperative mortality in females (all p < 0.05). Multivariate Cox regression confirmed a significant difference in 1-year mortality (PSM cohort: HR = 1.630, 95% CI: 1.046–2.542, p < 0.05), while no significant difference was found in 30-day mortality between groups (PSM cohort: HR = 1.444, 95% CI: 0.601–3.469, p > 0.05). Stratified and sensitivity analyses further confirmed these results. Conclusion Female sex is an independent predictor of 1-year mortality following CABG surgery. Graphical Abstract