Medicare Part D formulary coverage since program inception: are beneficiaries choosing wisely?

To evaluate how Medicare Part D formulary composition has changed since program inception, including comparison of plans eligible for full premium subsidy (ie, benchmark plans) with their counterparts.

The study used publicly available data released by the Centers for Medicare & Medicaid Services to generate snapshots of formulary coverage and enrollment levels in each plan year. The analysis included all Part D plans and tracked formulary coverage of 152 of the most common brand name and generic drugs prescribed to seniors.

Since 2006, the number of products available without restriction has increased and the number of drugs not on formulary has decreased. However, it appears that beneficiaries (subsidized beneficiaries in particular) may not be using their open-enrollment periods to reevaluate the available plan offerings.

Beneficiaries need to reevaluate the Part D options available on an annual basis to maintain enrollment with the most appropriate plan available. Although all plans meet the proscribed formulary requirements, some plans offer richer drug coverage with more drugs available on an unrestricted basis. Benchmark plan status allows Part D plans to maintain or gain significant Medicare enrollment from year to year. Careful oversight should be provided to ensure that the level of formulary coverage offered at benchmark and other plans remains consistent.