Plain Language Summary
Retrospective comparative analysis evaluating how the Inflation Reduction Act's 2025 Medicare Part D reforms (eliminating the coverage gap and establishing a $2,000 annual out-of-pocket cap) affected coverage and access to high-cost medications including semaglutide. Examines insurer formulary responses to the IRA changes and their implications for GLP-1 RA accessibility in Medicare beneficiaries. Provides policy analysis of how pharmaceutical pricing reform affects real-world semaglutide access for elderly patients who most need cardiovascular and metabolic risk reduction.
Abstract
PURPOSE: The Inflation Reduction Act (IRA) introduced significant reforms to Medicare Part D in 2025, aiming to reduce medication costs for beneficiaries by eliminating the coverage gap ("donut hole") with a $2,000 annual out-of-pocket cap. However, insurers' responses to these policy reforms-and their potential implications for medication affordability and access-have not been systematically evaluated.
METHODS: This was a retrospective comparative analysis of Medicare Part D plans (standalone prescription drug plans [PDPs] and Medicare Advantage prescription drug [MAPD] plans) comparing plan structure, formulary coverage, utilization management, and cost-sharing details from January 2024 to January 2025. Analyses were conducted using publicly available Centers for Medicare & Medicaid Services (CMS) datasets. Primary outcomes included changes in annual deductible amounts, cost-sharing structures (co-payment vs co-insurance), formulary coverage and utilization management practices, and patient out-of-pocket costs for glucagon-like peptide 1 (GLP-1) receptor agonists, including first-fill cost burden.
RESULTS: Across PDPs, mean annual deductibles significantly increased from $384.7 (95% CI, $369.2-$400.1) to $454.0 (95% CI, $432.9-$475.1); MAPD plans showed a greater increase from $98.7 (95% CI, $93.6-$103.8) to $249.0 (95% CI, $241.4-$256.6). In MAPD plans, co-insurance-style coverage utilization drastically increased for tier 3 medications (from 6.3% in 2024 to 38.1% in 2025). Specifically for GLP-1 agonists, while overall coverage decreased, coverage expanded for preferred drugs like subcutaneous semaglutide and tirzepatide. However, first-fill out-of-pocket expenses increased substantially due to higher deductibles and increased costs associated with co-insurance-style coverage. The rate of first-fill costs exceeding $600 rose from 40% to 45% (2024) to over 80% (2025) in PDPs and from less than 1% to approximately 13% in MAPD plans.
CONCLUSION: Medicare Part D plans in 2025 were strategically designed to increase beneficiaries' financial responsibilities via higher deductibles, increased co-insurance cost sharing, and restricted formulary coverage. While overall annual patient medication cost burdens will decrease, the cost of filling each medication will increase, which may negatively impact medication access and adherence.
Authors
Zhang, Yi Wolf; Blyumin, Michael G; Qu, Cori; Guo, Xu; Zhang, Minlu