Association of Hospital and Physician Characteristics and Care Processes with Racial Disparities in Procedural Outcomes among Contemporary Patients Undergoing Coronary Artery Bypass Grafting Surgery

Background - Previous studies have reported that black patients undergoing coronary artery bypass surgery had worse outcomes than white patients, even after accounting for patient factors. The degree to which clinician, hospital, and care factors account for these outcome differences remains unclear. Methods and Results - We evaluated procedural outcomes in 11 697 blacks and 136 362 whites undergoing isolated coronary artery bypass surgery at 663 Society of Thoracic Surgery Database participating sites (January 1, 2010 to June 30, 2011) adjusted for patients' clinical and socioeconomic features, hospital and surgeon effects, and care processes (internal mammary artery graft and perioperative medications use). Relative to whites, blacks undergoing coronary artery bypass surgery were younger, yet had higher comorbidities and more adverse presenting features. Blacks were also more likely to be treated at hospitals with higher risk-adjusted mortality. The use of internal mammary artery was marginally lower in blacks than in whites (93.3% versus 92.2%, P<0.0001). Unadjusted mortality and major morbidity rates were higher in blacks than in whites (1.8% versus 2.5%, P<0.0001) and (13.6% versus 19.4%, P<0.0001), respectively. These racial differences in outcomes narrowed but still persisted after adjusting for surgeon, hospital, and care processes in addition to patient and socioeconomic factors (odds ratio, 1.17; 95% confidence interval, 1.00-1.36 and odds ratio, 1.26; 95% confidence interval, 1.19-1.34, respectively). Conclusions - The risks of procedural mortality and morbidity after coronary artery bypass surgery were higher among black patients than among white patients. These differences were in part accounted for by patient comorbidities, socioeconomic status, and surgeon, hospital, and care factors, as well, as suggested by the reduction in the strength of the race-outcomes association. However, black race remained an independent predictor of outcomes even after accounting for these differences.