Outcomes in patients undergoing coronary artery bypass graft surgery in the United States based on hospital volume, 2007 to 2011

Objective: To examine national trends in coronary artery bypass grafting (CABG) volume between 2007 and 2011, and analyze in-hospital outcomes after CABG surgery stratified according to hospital volume. Methods: We analyzed all patients who underwent isolated CABG surgery between 2007 and 2011 in the National Inpatient Sample database. Trends in procedure volume and rates of adverse in-hospital outcomes were examined. Multivariate propensity-score adjusted analysis was performed to compare in-hospital mortality for hospitals based on quartiles of CABG volume. Results: The frequency of isolated CABG decreased by 25.4% from 2007 to 2011 (from 326 cases per million adults to 243 cases per million adults), with the most marked decline at higher-volume centers. Patients in the highest-volume quartile were more likely to have a history of previous CABG, previous percutaneous coronary intervention, peripheral vascular disease, hypertension, or chronic renal failure. In-hospital mortality was highest in low-volume centers. In multivariate logistic regression analysis, low hospital volume was an independent predictor of in-hospital all-cause mortality (adjusted odds ratio, 1.39; 95% confidence interval, 1.24-1.56; P < .001). Conclusions: The rate of CABG procedures has declined, mainly at high-volume centers. Low CABG volume is associated with an increase in in-hospital mortality.