Changes in use of lipid-lowering medications among black and white dual enrollees with diabetes transitioning from Medicaid to Medicare Part D drug coverage.

BACKGROUND The use of lipid-lowering agents is suboptimal among dual enrollees, particularly blacks. OBJECTIVES To determine whether the removal of restrictive drug caps under Medicare Part D reduced racial differences among dual enrollees with diabetes. RESEARCH DESIGN An interrupted time series with comparison series design (ITS) cohort study. SUBJECTS A total of 8895 black and white diabetes patients aged 18 years and older drawn from a nationally representative sample of fee-for-service dual enrollees (January 2004-December 2007) in states with and without drug caps before Part D. MEASURES We examined the monthly (1) proportion of patients with any use of lipid-lowering therapies; and (2) intensity of use. Stratification measures included age (less than 65, 65 y and older), race (white vs. black), and sex. RESULTS At baseline, lipid-lowering drug use was higher in no drug cap states (drug cap: 54.0% vs. nondrug cap: 66.8%) and among whites versus blacks (drug cap: 58.5% vs. 44.9%, no drug cap: 68.4% vs. 61.9%). In strict drug cap states only, Part D was associated with an increase in the proportion with any use [nonelderly: +0.07 absolute percentage points (95% confidence interval, 0.06-0.09), P<0.001; elderly: +0.08 (0.06-0.10), P<0.001] regardless of race. However, we found no evidence of a change in the white-black gap in the proportion of users despite the removal of a significant financial barrier. CONCLUSIONS Medicare Part D was associated with increased use of lipid-lowering drugs, but racial gaps persisted. Understanding non-coverage-related barriers is critical in maximizing the potential benefits of coverage expansions for disparities reduction.