Effects of race, with or without gender, on operative mortality after coronary artery bypass grafting: A study using the society of thoracic surgeons national database

Background. Although gender is known to be an independent predictor of 30-day operative mortality (OM) after coronary artery bypass grafting, the purpose of this study was to determine whether race - alone or in combination with gender - affects OM. Methods. For 1994 to 1996, The Society of Thoracic Surgeons database records for 441,542 coronary artery bypass grafting-only procedures were analyzed. Baseline annual multivariate models were built. Gender and race were added to each model. Risk-adjusted OM rates were then calculated for race, gender, and their combination. Patients were also stratified into groups of comparable predicted OM to allow for a direct comparison of risk-matched Caucasians and non-Caucasians. Results. Of the procedures, 28.2% were on women and 8.5% on non-Caucasians. Overall, OM was 3.29%. Multivariate risk-adjusted OM varied by gender and race (p < 0.10). Risk-adjusted OM rates (with 95% confidence intervals) were 4.0% (3.9% to 4.1%) for females and 3.2% (3.2% to 3.3%) for males. Risk-adjusted OM rates were 3.9% (3.7% to 4.1%) for non-Caucasians and 3.3% (3.2% to 3.3%) for Caucasians. Among equally risk-matched Caucasians and non-Caucasians, non-Caucasians had significantly higher (p < 0.005) mortality among the lower risk subgroups (up to 10% predicted OM) but not among the higher risk subgroups. Conclusions. Race and gender are independent predictors of adverse outcome following coronary artery bypass grafting, holding all other risk factors constant.