Presentation (CTI)

OBJECTIVES: To describe changes in Medicare Part D formulary coverage of brand-only drugs in competitive classes from 2024 to 2025.
METHODS: Medicare Part D formulary inclusion data for 2024 and 2025 were obtained using the SSR Health Part D Formulary Tool. SSR Health-assigned classes were included if they reflected a single pharmacological group or class in US Pharmacopoeia and had at least four commercially available, policy-relevant brand-only drugs. Policy-relevant brand-only drugs excluded drugs administered by a health care provider, not covered by Part D, and/or primarily covered under Part B. Further, classes with legislative coverage mandates or restrictions were excluded, as were those with limited therapeutic relevance to older adults (e.g., contraceptives) and that had a first generic, biosimilar, or authorized generic launch for a primarily Part D-covered drug in 2024. Descriptive statistics were conducted on the primary outcome: the proportion of beneficiaries across all Part D plans with coverage of the included drugs.
RESULTS: Coverage among the 48 included drugs across 9 classes declined for most included drugs (n = 39/48, 81.3%). Across the 48 included drugs, the median covered access for all beneficiaries was 69.2% (IQR: 30.6%-93.2%) in 2024 and was 57.8% (IQR: 20.3%, 89.7%) in 2025. Drugs for which fewer than half of beneficiaries had covered access in 2024 (n = 18) had larger declines in access (median: -20.2%) than those for which 50-80% (n = 12, median: -10.9%) or >80% of beneficiaries (n = 18, median: -1.7%) had access in 2024. In all studied classes, at least half of included drugs had reduced coverage in 2025 (median: 87.5% of drugs in class, IQR: 68.8%-100%).
CONCLUSIONS: These findings describe widespread and large reductions in beneficiary access to drugs in competitive classes in a single year, supporting concerns around the IRA’s impact on Medicare Part D formulary design.