IRA Drug Provisions Linked to Significant Drop in Medicare Medication Nonadherence

High prescription drug costs have long been one of the most pressing challenges in American health care, contributing to medication nonadherence and poor clinical outcomes. More than 1 in 4 US adults report difficulty affording their medications, and the problem is particularly acute for older adults on Medicare managing multiple chronic conditions.¹ Two studies published this week now offer the first rigorous evidence that the Inflation Reduction Act’s (IRA’s) 2024 prescription drug provisions have translated into meaningful improvements in medication adherence, a finding with significant implications for chronic disease management nationwide.

Two major IRA provisions took effect on January 1, 2024. The first eliminated the 5% coinsurance requirement for catastrophic coverage under Medicare Part D, effectively capping annual out-of-pocket (OOP) prescription drug costs at approximately $3300. The second expanded eligibility for full low-income subsidies (LIS)—which limit premiums, deductibles, and co-payments—to beneficiaries with incomes between 135% and 150% of the federal poverty level (FPL), a group that had previously received only partial subsidies. As of mid-2024, approximately 1.5 million beneficiaries had saved close to $1 billion from the catastrophic coverage change alone.^1,2

The first study, published in JAMA Internal Medicine, employed a difference-in-differences design using 2021-2024 National Health Interview Survey data.¹ The analysis compared 1454 Medicare Part D beneficiaries aged 62 to 67 years with 3797 privately insured adults of similar ages, excluding insulin users and those already receiving full LIS, to isolate the effect of the 2024 provisions. Following implementation, cost-related medication nonadherence declined by 4.9 percentage points among Medicare beneficiaries relative to comparators (95% CI, −8.8 to −1.0)—a reduction the authors noted was larger in magnitude than that observed following the initial rollout of Medicare Part D itself.

The effect was even more pronounced among beneficiaries with 2 or more chronic conditions, who experienced a reduction of 7.8 percentage points in cost-related nonadherence (95% CI, −12.9 to −2.8). The findings were consistent across multiple sensitivity analyses and alternative comparator groups, lending further confidence to the results. By contrast, no meaningful differential change was observed in broader health care–related financial strain, such as difficulty paying medical bills. The authors suggest that prescription drug savings, although meaningful, may not be large enough in the short term to reduce preexisting medical debt or ease anxiety about future medical expenses more broadly.

Income-Based Subsidies Drive Gains in Cardiovascular Adherence

A companion brief report in the Journal of the American College of Cardiology examined 28,010 Medicare beneficiaries 65 years and older with cardiovascular risk factors or conditions, a population that frequently faces steep OOP costs for brand-name cardiometabolic therapies.² Guideline-directed therapy for systolic heart failure, for example, can involve multiple brand-name agents costing more than $3000 annually. Among beneficiaries newly eligible for full LIS under the IRA—those with incomes between 135% and 150% of FPL—cost-related nonadherence fell by 5.5 percentage points (95% CI, −10.9 to −0.2), corresponding to approximately 70,000 fewer socioeconomically vulnerable older adults with cardiovascular disease facing financial barriers to filling their prescriptions.

However, eliminating catastrophic coverage coinsurance alone among beneficiaries not eligible for LIS did not produce a statistically significant reduction in nonadherence (−1.7 percentage points; 95% CI, −3.9 to 0.5). This divergence suggests that income-based subsidies targeting lower-income beneficiaries may be the more potent policy lever for improving adherence in the cardiovascular population, at least in the near term.

Policy Outlook

Both sets of authors point to additional IRA provisions that may further reduce nonadherence in the coming years.^1,2 A $2000 annual OOP cap for all Medicare Part D enrollees took effect in January 2025, offering broader financial protection than the 2024 catastrophic coverage changes. Negotiated prices for select high-cost medications, including several cardiovascular therapies, are expected to begin in 2026. However, both studies flag that some Medicare Part D plans have responded to the IRA’s redesign by altering their benefit structures in ways that could increase cost-sharing for certain drugs, potentially blunting the policy’s intended gains.

Together, the studies strengthen the evidence base for prescription drug reform and make a compelling case for extending similar protections beyond Medicare. The authors suggest potential models include uniform insulin cost-sharing limits and income-related caps on OOP spending for high-value chronic disease medications in commercial and employer-sponsored plans. Sustained improvements in adherence, particularly among patients managing multiple or costly conditions, could ultimately translate into fewer hospitalizations, emergency visits, and adverse cardiovascular events.

References

1. Marinacci LX, Mein S, Rome BN, Wadhera RK. Cost-related medication nonadherence after the Inflation Reduction Act. JAMA Intern Med. Published online March 9, 2026. doi:10.1001/jamainternmed.2026.0012

2. Marinacci LX, Oseran AS, Narasimmaraj P, Engel-Rebitzer E, Wadhera RK. Medication adherence among Medicare beneficiaries with cardiovascular conditions after the 2024 Inflation Reduction Act provisions. J Am Coll Cardiol. Published online February 2, 2026. doi:10.1016/j.jacc.2025.12.083