This prospective study analyzed the outcomes for 3,728 coronary artery bypass (CAB) surgery patients at Cedars-Sinai Medical Center in Los Angeles, California, a private university affiliated teaching hospital, to determine whether racial differences existed in survival outcome 5 years after coronary artery bypass grafting surgery and to determine if existing differences could be attributed to differences in preoperative characteristics. Data on preoperative and postoperative characteristics were obtained from a computerized database. Baseline data was collected from the patient’s medical chart at the index hospital admission. Subsequent annual follow-up data was obtained from these medical charts up until death. The sample population had similar health care coverage. Blacks (60%) and whites (57%) were primarily covered by Medicare and the remaining (38% of blacks and 42% of whites) had private medical insurance. A cardiac event was the cause of death for 68% of blacks and 67% of whites.

The findings of this study indicate that “being black was a risk factor for survival (hazard ratio, 1.97; P=.001). This was calculated using a maximum follow-up period of 8 years (mean, 3.5 years).” The results suggest that by “5 years after surgery, the unadjusted risk of death in black patients is double that of white patients (36% vs. 18%).” This “increased mortality risk associated with being black remains statistically significant after adjustment for other risk factors (adjusted hazard ratio, 2.10; P-to remove, .001).” At one year after surgery, blacks had an 84.3% survival probability compared to 92.1% for whites. By five years, the survival probability gap had increased dramatically, as blacks had a 63.9% probability of surviving whereas whites had an 81.8% survival probability. The authors state that “even after adjusting for traditional risk factors, blacks have more than twice the risk of death compared with white patients at 5 years.”

A potential limitation of this study is the small proportion of blacks in the CAB surgery population (3%) compared to that “of the institution (17%) and the Los Angeles metropolitan area (12%).” This problem, “faced by other investigation of cardiac interventions in blacks,” in fact “partly reflects the racially disparate use of CAB surgery.” Furthermore, “the appearance of significant differences despite small sample sizes, suggests a conservative estimate of true inter-group differences.”

Unlike many previous studies, the sample population of this study was composed of middle class blacks who were medically insured, therefore eliminating a “potential variable in determining outcome and suggests that factors other than affordability of health care are operative in this group.”