Out-of-plan medication in Medicare Part D

To determine the extent to which Medicare Part D enrollees fill unadjudicated prescriptions for diabetes, hypertension, and hyperlipidemia medications outside of the Part D benefit.

Retrospective analysis of prescriptions filled by community-dwelling beneficiaries continually enrolled in a Medicare Part D plan in 2009.

We used the Medicare Current Beneficiary Survey to compare self-reported prescription fills for oral antidiabetes medications, renin-angiotensin-aldosterone system inhibitors, and statins to adjudicated prescription drug event data recorded by Part D plan sponsors. For unadjudicated prescriptions with no evidence of Part D payment, we determined whether the fills were paid for in cash, filled through VA pharmacies or discount generic programs, or had other reported sources of coverage.

A total of 6.2% of all prescriptions filled by Part D beneficiaries were unadjudicated, ranging from 5.3% of all oral antidiabetes medications to 6.8% of statins. Cash prescriptions accounted for more than half of all out-of-plan use, but we found little evidence of unadjudicated out-of-plan use of discount generics. Prescriptions filled at VA pharmacies and those with other reported sources of coverage each accounted for about 1% of total fills.

Out-of-plan medication use accounts for a small share of total prescriptions filled by Part D beneficiaries. Nevertheless, CMS should continue to work with plan sponsors to develop initiatives that facilitate the collection of beneficiaries' complete utilization data, as a more complete reporting could improve the quality of care delivered to Part D enrollees.