Medicare drug caps tied to more use of expensive meds

Clinical takeaway: Cost is less likely to block a Medicare patient from filling an expensive prescription now that annual out-of-pocket spending is capped. The change showed up mainly for specialty and oncology drugs.

High cost-sharing has long kept some Medicare patients from filling the medications they need, with roughly 1 in 5 adults over 65 reporting cost-related nonadherence in a 2022 survey. The Inflation Reduction Act (IRA) capped annual out-of-pocket Part D spending starting in 2024, lowering it to $2,000 in 2025. A new analysis examines if this translated to more medication use; it found that fills did rise after the cap, concentrated in the most expensive medications.

Use of very-high-cost medications, those above $7,000 a month, rose 22.7% in Medicare relative to commercial insurance after the cap, the only price tier with a significant change in the primary analysis. Oncology drugs made up the largest share of that category. Cheaper drugs showed no significant difference, consistent with cost being the binding constraint only at the top of the price range.

The cohort study analyzed 3053 medications covering 93% of gross Medicare Part D spending in 2023, drawn from an all-payer pharmacy database. Using a difference-in-differences design, the authors compared quarterly per-capita fills in Medicare against commercially insured patients from 2022 through 2025, treating the January 2024 cap as the intervention. Drugs were grouped into four monthly-cost tiers, from under $100 to above $7,000.

The pattern fits what the caps were designed to do: relief concentrated where out-of-pocket costs had been high enough to stop patients from filling. The access gains come with a tradeoff. Part D spending rose faster than projected over the same period, and some of the higher use may reflect a shift toward pricier alternatives now that patients face similar costs either way.

"The Part D annual spending caps in the IRA applied to all medications and represented a large reduction in cost for many patients who previously could pay $10,000 or more for some expensive medications," the authors wrote.

Source: Cai CL, et al. JAMA Health Forum. 2026 Jun 18. Changes in medication use after Medicare Part D annual out-of-pocket spending caps