Explaining racial disparities in mortality after abdominal aortic aneurysm repair

Abstract

Black patients have a higher mortality rate than nonblacks after abdominal aortic aneurysm repair. We sought to understand the factors responsible for this racial disparity in the mortality rate after aneurysm repair. The Medicare database (2001-2006) was used to identify 160,785 patients undergoing open and endovascular abdominal aortic aneurysm repairs. We used risk-adjusted mortality as our primary measure of quality and logistic regression to determine the relationship between race and mortality, sequentially adding contributing factors including patient characteristics, the type of repair (endovascular vs open repair), socioeconomic status, and hospital quality. From these sequential regression models, we estimated the proportion of the disparity that can be explained by each factor. Black patients had a 36% higher risk-adjusted mortality after aneurysm repair than nonblack patients (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.20-1.53). Even after accounting for the type of repair, a significant difference in mortality remained (OR, 1.33; 95% CI, 1.18-1.50). Mortality rates were higher in hospitals treating a higher proportion of black patients. Adjusting for these differences in hospital quality, this disparity was no longer significant (OR, 1.07; 95% CI, 0.93-1.25). We estimate that 29% of the observed disparity in mortality is caused by patient comorbidities, 6% from the use of endovascular repairs, 26% due to socioeconomic factors, and 25% because black patients receive care in lower-quality hospitals. Although many factors contribute, a large proportion of observed disparities in outcomes are attributable to black patients receiving care in lower-quality hospitals. Efforts aimed at improving disparities must focus on improved access to high-quality hospitals and improved resources at the hospitals that treat higher proportions of black patients.