Gender and outcomes after coronary artery bypass grafting: a propensity-matched comparison.

OBJECTIVE: Our objective is to determine whether gender is a marker or a causal influence for poor outcomes after coronary revascularization.
METHODS: Propensity-modeling techniques were used to investigate whether gender adversely impacts outcomes after coronary revascularization. A parsimonious explanatory model was developed by bootstrap bagging with variable selection from 64 baseline and 37 operative variables. Propensity scores were calculated from a logistic model that included the parsimonious model and additional baseline variables. Greedy matching techniques were applied to match female and male patients to the nearest propensity scores. Comparisons were made among the propensity-matched women and men.
RESULTS: Of the 15,597 patients undergoing isolated coronary artery bypass graft surgery, only 26% of the 3596 women were matched on propensity scores with men. Distribution of covariates among the matched pairs was, on average, equal. Postoperative mortality (P =.76), neurologic morbidity (global deficit P =.07, focal deficit P =.51), infection (sepsis P =.88), mediastinitis (P =.18), renal failure (P =.84), intra-aortic balloon pump usage (P =.61), and reoperation for bleeding (P =.10) were similar among women and men. Occurrence of Q-wave myocardial infarction (P = <.01), postoperative inotropic usage (P = <.01), and prolonged ventilatory support (P =.02) were more common in women compared with propensity-matched men.
CONCLUSIONS: The preoperative profiles of women and men are markedly different. Propensity matching women and men was difficult, because only 26% of women were able to be matched with men. However, in well-matched patients, female gender was not associated with increased mortality and had minimal impact on morbidity after coronary artery bypass grafting.