Contributions of Geography and Nongeographic Factors to the White-Black Gap in Hospital Quality for Coronary Heart Disease: A Decomposition Analysis

Background: Differences in hospital proximity and nongeographic factors affect disparities in hospital quality for heart disease, but their relative contributions are unknown. The current study quantifies the influences of these factors on the white-black gap in high- and low-quality hospital use for acute myocardial infarction (AMI) and coronary artery bypass grafting (CABG) surgery. Methods and Results: We used Medicare claims to identify fee-for-service Medicare beneficiaries aged 65 and older hospitalized during 2009–2011 with AMI (n=384 443) and CABG (n=71 411). Hospital quality was measured using publicly available AMI mortality rates. In national and regional analyses, we used conditional multinomial logit models to estimate the white-black gap in high- and low-quality hospital use and decompose the gap into geographic and nongeographic contributions. Overall, more whites used high-quality hospitals for both conditions (34.8% versus 32.4% for AMI; 39.0% versus 29.9% for CABG; P<0.001), but after accounting for distance to hospitals, the white-black gap was significant only for CABG (9.1%; P<0.001). The nongeographic component was significant for both conditions (3.4% for AMI and 7.7% for CABG; P<0.001) and accounted for nearly the entire gap for CABG. In contrast, hospital geographic proximity was not significant. In regional analyses, white beneficiaries had higher rates of high-quality hospital use in the Northeast (CABG) and South (AMI and CABG), whereas black had higher rates of high-quality hospital use in the Midwest (AMI). Conclusions: White-black differences in high-quality hospital use were significant for CABG and related to nongeographic factors. Interventions should consider health system and contextual reasons for these disparities.