Medicare Part D plans tightened drug coverage more than commercial plans after IRA changes

New National Pharmaceutical Council research finds Medicare Part D plans were likelier than commercial plans to restrict coverage in competitive drug classes after the Inflation Reduction Act took effect. The study says the shifts affected millions of beneficiaries and may signal unintended access consequences as IRA implementation continues.

Why it matters: - Medicare beneficiaries are losing coverage for some branded medicines at a higher rate than people in commercial plans. - The coverage declines could affect access to therapeutic alternatives in competitive drug classes. - The findings raise questions about whether current Part D formulary processes are protecting patient access as IRA changes take hold.

What happened: - The National Pharmaceutical Council published research in Health Affairs Scholar on changes in Medicare Part D coverage after the Inflation Reduction Act. - The study compared Medicare standalone prescription drug plans and Medicare Advantage Prescription Drug plans with commercial insurance. - The analysis covered 2024-2026 formulary data for brand-only medicines in 16 competitive drug classes. - Competitive classes were defined as classes with at least three commercially available, eligible brand-only drugs. - The IRA’s Part D changes included a cap on patient out-of-pocket costs and increased catastrophic phase liability for plans and manufacturers, effective Jan. 1, 2025.

The details: - The study found broader declines in coverage across competitive classes in Medicare Part D after the IRA changes. - Medicare coverage declined in both 2025 and 2026. - Standalone Part D plans saw larger reductions than Medicare Advantage Prescription Drug plans. - In 2024, commercial plans had the highest average coverage rate at 71.4%. - MA-PD plans averaged 52.3% coverage in 2024. - PDP plans averaged 47.4% coverage in 2024. - The study found an average of 4.5 million Medicare beneficiaries lost insurance coverage for previously covered branded medicines across the 16 classes. - That total included 2.7 million beneficiaries in PDP plans and 1.8 million in MA-PD plans. - At the drug level, coverage decreases from 2024-2026 affected more than 5% of beneficiaries for over half of the included drugs in PDP plans. - That affected 30 of 59 drugs, with a decline of at least 1.14 million beneficiaries per drug. - At the class level, coverage declined by at least five percentage points on average from 2024-2026 in 10 of 16 classes in PDPs. - The same threshold was met in seven of 16 classes in MA-PD plans. - Commercial plans met that threshold in three included classes. - The research says incentives to add formulary exclusions may be highest in classes with multiple branded prescription drugs, because plans can use exclusions to negotiate higher rebates. - Dr. Campbell, NPC chief science officer and a study co-author, said the findings are consistent with one theorized unintended consequence of the IRA.

Between the lines: - The study adds to a growing body of evidence that the IRA may be reshaping plan behavior in ways that reduce coverage breadth. - The results suggest plans may be responding to new Part D economics by narrowing formularies in categories with more competition. - The comparison with commercial coverage strengthens the case that the trend is not just a market-wide shift.

What's next: - The authors say more research is needed as IRA implementation continues. - Future work should track Medicare patients’ access to medicines and health outcomes. - The study also points to a need to watch how Part D formulary review processes affect beneficiary access going forward.

The bottom line: - After the IRA’s Part D overhaul, Medicare plans appear more likely than commercial plans to cut coverage in competitive drug classes, potentially narrowing access for millions of beneficiaries.

More information: NPC