Who enrolls in the Medicare Part D prescription drug benefit program? Medication use among patients with heart failure.

BACKGROUND: Dispensing data from Medicare Part D standalone prescription drug plans are now available, but characteristics of enrollees with heart failure have not been well described. METHODS AND RESULTS: We identified 81 874 patients with prevalent heart failure as of January 1, 2010, in a nationally representative 5% sample of Medicare beneficiaries. We classified patients according to enrollment in a Medicare Part D plan as of January 1, 2010. Demographic characteristics, comorbid conditions, and prescriptions were compared by enrollment status. A total of 49 252 (60.2%) were enrolled in a Medicare Part D plan as of January 1. Enrollees were more often women, black, and of lower socioeconomic status. Enrollees with heart failure more often filled prescriptions for loop diuretics than angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, β-blockers, or aldosterone antagonists. During the first 4 months of 2010, 5444 (12.3%) reached the coverage gap, and 566 (1.3%) required catastrophic coverage beyond the gap. CONCLUSIONS: Medicare beneficiaries with heart failure differ significantly according to enrollment in Part D prescription drug plans and represent a population underrepresented in clinical efficacy trials. Many face the coverage gap, and few select Medicare Part D plans that provide coverage during the gap. Linking Medicare Part D event data with clinical registries could help to determine whether eligible enrollees are undertreated for heart failure.