Quality of care and racial disparities in medicare among potential ACOs

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.

Figure 1

Quality of care for beneficiaries with cardiovascular disease or diabetes by race and size of provider group. Performance on six quality measures (Panels A–F) are displayed by provider group size and race. Compared with small provider groups, racial differences in LDL cholesterol testing (Panel B) and retinal exams (Panel C) were significantly smaller for large groups (P ≤ 0.01) as a result of higher rates for black beneficiaries with diabetes, but racial differences in other quality measures did not differ by group size. Compared with small groups, both medium-sized and large groups performed better on all process measures for both white and black beneficiaries (P ≤ 0.01) but did not have lower rates of hospitalization for ACSCs. ACSC = ambulatory care sensitive condition; DM = diabetes mellitus; CVD = cardiovascular disease; LDL = low-density lipoprotein.

Figure 2

Racial difference in quality for beneficiaries with cardiovascular disease or diabetes by provider group size. Black–white differences in six quality measures are displayed by the size of beneficiaries’ assigned provider group. Categories of provider group size are based on eligibility thresholds for participation in the Medicare ACO programs: small or ineligible for ACO programs (≤ 5,000 assigned beneficiaries); medium-sized or eligible for the Shared Savings Program but not for the Pioneer program (5,000–14,999 assigned beneficiaries); and large or eligible for the Pioneer program (≥ 15,000 assigned beneficiaries). Error bars indicate 95 % confidence intervals. ACSC = ambulatory care sensitive condition; DM = diabetes mellitus; CVD = cardiovascular disease; LDL = low-density lipoprotein.

Figure 3

Racial disparities in quality of care by quartile of provider group performance for white beneficiaries among provider groups sufficiently large for ACO programs. For each quality measure, provider groups sufficiently large to participate in ACO programs (medium-sized and large groups) were categorized into quartiles according to their performance for white beneficiaries. For each quartile, the adjusted racial disparity (absolute value of the difference between black and white beneficiaries) is shown for each of the following measures: provision of all three diabetes services (hemoglobin A_1c testing, LDL cholesterol testing, and retinal examination) to beneficiaries with diabetes; LDL cholesterol testing for patients with cardiovascular disease; hospitalization for an ACSC related to diabetes or cardiovascular disease; and hospitalization for any ACSC. For each quality measure, the correlation between performance for white beneficiaries and the black–white difference in performance is presented with 95 % confidence intervals and two-sided p-values. Lower rates of hospitalization of white beneficiaries for ACSCs related to diabetes or cardiovascular disease were correlated with smaller black–white differences. Correlations between quality for white beneficiaries and black–white difference were not statistically significant for other quality measures.

Figure 4

Racial disparities in quality of care within and between provider groups sufficiently large for ACO programs. For each quality measure, the total disparity among provider groups of sufficient size to participate in ACO programs (medium-sized and large groups) was decomposed into within-group differences in quality and differences in quality related to between-group differences in racial composition. The proportion of the total unadjusted racial disparity attributable to racial differences within provider groups ranged from 53 % [2.1/(2.1 + 1.9)] to 95 % [2.0/(2.0 + 0.1)] across quality measures, while differences between groups in the racial composition of assigned populations of beneficiaries accounted for the remaining 5 % to 47 %.