How Lack of Subsidized Prescription Drug Coverage Affects Medication Use by Low-income Medicare Beneficiaries

Abstract Introduction Beginning in 2024, the Inflation Reduction Act (IRA) extended eligibility for full Medicare Part D low-income subsidies (LIS) to all partial-subsidy recipients but did not address the issue of low participation rates for both full and partial subsidies. This study examines how lack of LIS affects medication use among Medicare beneficiaries who meet program eligibility criteria but fail to enroll and whether alternative sources of prescription coverage mitigate the lack of subsidies. Methods This study used data from the 2019 Medicare Current Beneficiary Survey. Results We found that LIS recipients averaged 49 prescriptions annually versus 25 for LIS-eligible nonenrollees and were 10% less likely to report cost-related nonadherence. Regression models controlling for differences between the two groups showed that LIS recipients filled 45% more prescriptions (P<.001) and that nonadherence was 1.4 times greater among those without subsidies (p=0.014). Non-enrollees with unsubsidized Part D filled 39% fewer prescriptions than LIS recipients (p<0.001). Conclusion These findings provide a powerful policy endorsement of the value of Part D LIS for Medicare beneficiaries. Expanded LIS provided under provisions of the IRA together with a robust program designed to maximize LIS enrollment should lead to improved medication utilization within the eligible low-income beneficiary population.