Female sex as an independent predictor of morbidity and survival after isolated coronary artery bypass grafting

Abstract

Background: This study sought to determine whether female sex was an independent risk factor for combined in-hospital morbidity, mortality, and long-term survival after coronary artery bypass grafting (CABG).

Methods: Data were collected prospectively for 1,114 (23.5%) women and 3,628 (76.5%) men operated on between January 1, 1996 and December 31, 2004 with median follow-up of 7.9 years (interquartile range 3.55 to 10.5). The combined morbidity end point was defined as in-hospital renal failure, stroke, ventilation for more than 24 hours, deep sternal wound infection, reoperation, myocardial infarction (MI), and mortality less than 30 days after discharge. The long-term all-cause and cardiac mortality outcomes were analyzed using multivariate proportional hazard regression.

Results: Females were older, with lower body surface area, and generally had more significant comorbid conditions than did males (p<0.05). Female sex was associated with increased odds of the combined morbidity end point (adjusted odds ratio [OR]=1.29; 95% confidence interval, 1.04 to 1.59, p=0.02). There were 868 deaths (18.3% of total sample) during the follow-up period, and 305 deaths (n=305 [35.1%] of deaths) were deemed to be of cardiac causes. In adjusted survival models, female sex was associated with cardiac mortality (hazard ratio [HR]=1.28; 95% confidence interval, 0.96 to 1.73; p=0.10) but not with all-cause mortality (HR=0.92; 95% confidence interval, 0.77 to 1.11; p=0.38).

Conclusions: Female sex was associated with early combined morbidity and long-term cardiac mortality but not long-term all-cause mortality. A greater proportion of concomitant risk factors characterize female patients undergoing CABG.