Abstract
BACKGROUND: The Medicare Accountable Care Organization (ACO) programs encourage integration of providers into large groups and reward provider groups for improving quality, but not explicitly for reducing health care disparities. Larger group size and better overall quality may or may not be associated with smaller disparities. OBJECTIVE: To examine differences in patient characteristics between provider groups sufficiently large to participate in ACO programs and smaller groups; the association between group size and racial disparities in quality; and the association between quality and disparities among larger groups. DESIGN AND PARTICIPANTS: Using 2009 Medicare claims for 3.1 million beneficiaries with cardiovascular disease or diabetes and linked data on provider groups, we compared racial differences in quality by provider group size, adjusting for patient characteristics. Among larger groups, we used multilevel models to estimate correlations between group performance on quality measures for white beneficiaries and black-white disparities within groups. MAIN MEASURES: Four process measures of quality, hospitalization for ambulatory care-sensitive conditions (ACSCs) related to cardiovascular disease or diabetes, and hospitalization for any ACSC. KEY RESULTS: Beneficiaries served by larger groups were more likely to be white and live in areas with less poverty and more education. Larger group size was associated with smaller disparities in low-density lipoprotein (LDL) cholesterol testing and retinal exams, but not in other process measures or hospitalization for ACSCs. Among larger groups, better quality for white beneficiaries in one measure (hospitalization for ACSCs related to cardiovascular disease or diabetes) was correlated with smaller racial disparities (r = 0.28; P = 0.02), but quality was not correlated with disparities in other measures. CONCLUSIONS: Larger provider group size and better performance on quality measures were not consistently associated with smaller racial disparities in care for Medicare beneficiaries with cardiovascular disease or diabetes. ACO incentives rewarding better quality for minority groups and payment arrangements supporting ACO development in disadvantaged communities may be required for ACOs to promote greater equity in care.