Gender Differences in In-Hospital Outcomes After Coronary Artery Bypass Grafting

Women historically have a greater risk of operative mortality than men after coronary artery bypass grafting (CABG). There is paucity of contemporary data in gender outcomes of surgical revascularization and understanding modifiable factors that contribute to gender differences are critical for quality improvement and practice change. We, therefore, sought to examine whether the gender gap in CABG outcomes is closing in the contemporary era by conducting a retrospective analysis from the Nationwide Inpatient Sample database from 2003 to 2012. We included all patients who underwent isolated CABG surgery (n = 2,272,998; female n = 623,423 [27.4%]; male n = 1,649,575 [72.6%]). The annual rate of CABG surgeries decreased by 53.7% in men and 57.8% in women over the 10-year study period. Although internal mammary artery use in women was less frequent than in men in 2003 (77.4% vs 81.9%, p <0.001), a significant uptrend closed this gap by 2012 (86.2% vs 87.0%, ptrend 0.003). Overall, unadjusted in-hospital mortality was greater in women (3.2% vs 1.8%, p <0.001). Female gender remained an independent predictor of mortality after multivariate adjustment (odds ratio 1.40, 95% CI 1.36 to 1.43, p <0.001) across all age groups. However, in-hospital mortality decreased at a faster rate in women (3.8% to 2.7%, RR -29.1%, ptrend 0.002) than in men (2.2% to 1.6%, RR -25.7%, ptrend <0.001) from 2003 to 2012. In conclusion, CABG rates in the United States are decreasing over time, yet in-hospital mortality continues to improve. Women have worse in-hospital outcomes than men; however, the gender gap is slowly closing.