Hospital quality was associated with racial disparities in outcomes after coronary artery bypass graft (CABG) surgery in a study by Govind Rangrass, M.D., of the University of Michigan, Ann Arbor, and colleagues.

Racial disparities in mortality rates after CABG surgery are well established, but it is less known how receiving care at high-mortality, low-quality hospitals may contribute to racial disparities in surgical outcomes, according to the study background.

Researchers used the national Medicare database to identify 173,925 patients who underwent CABG surgery, of whom 14,882 (8.6 percent) were nonwhite.

Study findings indicate that nonwhite patients had 33 percent higher mortality rates after CAG surgery than white patients. In hospitals that treated the highest proportion of nonwhite patients (greater than 17.7 percent), the mortality rate was 4.8 percent for nonwhite patients and 3.8 percent in white patients. Patient factors, socioeconomic status and hospital quality explained 53 percent of the disparity seen between white and nonwhite patients. The study acknowledges a significant fraction of the racial disparity remains unexplained.

"Compared with white patients, nonwhite patients have a significantly higher mortality rate after CABG surgery. Decreased access to high-quality, low-mortality hospitals explains a large proportion of the observed racial disparity in mortality rates," the study concludes. "Other factors that may perpetuate racial disparities include regional variations in hospital quality, proximity to high-quality hospitals, and segregated referral patterns. Although our data could not directly address these factors, our study highlights the effects of hospital quality and serves as a springboard for further research in this area."