Affordability and adherence gains for Medicare Part D low-income subsidy recipients when low-income subsidy benefits expanded in 2024.

Background: The lowest-income beneficiaries enrolled in the Medicare Part D prescription drug program receive "full subsidies" that waive the premium and deductible and impose minimal copayments. Those with slightly higher incomes and assets may be eligible for "partial subsidies." Prior to 2024, individuals receiving partial subsidies faced reduced Part D premiums and deductibles and paid 15% coinsurance. Under provisions of the Inflation Reduction Act, recipients of partial subsidies were upgraded to full subsidies beginning in 2024. The objective of this pilot study was to assess whether the new policy is likely to reduce cost-related nonadherence to prescribed medications- a common problem faced by older adults even among those receiving subsidies.

Objective: To compare cost-related nonadherence among partial- vs full-subsidy recipients with similar characteristics.

Methods: We used 2019 Medicare Current Beneficiary Survey data for the study. The Medicare Current Beneficiary Survey is uniquely suited for this work because it contains administrative data on low-income subsidy enrollment plus extensive survey-based information on financial resources necessary to establish program eligibility and rates of cost-related nonadherence. Explanatory variables included sociodemographic characteristics, economic resources, work status, and health variables.

Results: We found that the partial-subsidy group reported significantly more cost-related nonadherence (39% vs 22%; P = 0.01) arising both from a lower propensity to fill some prescriptions (23% vs 12%; P = 0.03) and to more delays in filling others (29% vs 8%; P = 0.03). The differences were more pronounced for women and racial and ethnic minority groups in contrast to men and majority populations, respectively. Because the study samples were small, we could not conduct a detailed regression analysis.

Conclusions: The magnitude of cost-related nonadherence effects associated with partial-subsidy cost sharing suggests that the Inflation Reduction Act policy to expand low-income subsidies may boost medication adherence, most notably among women and racial and ethnic minority groups.