(HealthDay)—Hospital quality contributes to the racial disparities in outcomes after coronary artery bypass graft (CABG) surgery, according to research published online on Jan. 8 in JAMA Surgery.

Govind Rangrass, M.D., of the University of Michigan in Ann Arbor, and colleagues analyzed Medicare data from 173,925 patients to assess the effect of on racial disparities in following CABG surgery.

The researchers found that risk-adjusted mortality was 33 percent higher in nonwhite versus white patients after CABG. Among hospitals with the highest proportion of nonwhite patients (greater than 17.7 percent), mortality after CABG was 4.8 percent in nonwhite patients and 3.8 percent in . When the independent effects of each variable were evaluated, about 35 percent of the racial disparity in mortality after CABG was explained by variation in hospital quality. Adjustment for differences in socioeconomic status also contributed to the observed disparity, but nonwhite patients still had a 16 percent higher mortality rate even after both factors were taken into account.

"Hospital quality contributes significantly to in outcomes after CABG surgery," the authors write. "However, a significant fraction of this racial disparity remains unexplained."