Non-cost-related sources of medication nonadherence in the Medicare population.

Significant research and attention to date have focused on cost-related medication nonadherence as rising prescription drug prices worsen affordability and access for many Americans. This study investigated self-reported sources of medication nonadherence, measuring both cost- and non-cost-related medication nonadherence among community-dwelling Medicare Part D beneficiaries in 2022. A total of 13.7% of beneficiaries (4 589 843) reported some type of medication nonadherence; 7.5% reported medication nonadherence related to cost and 6.2% reported for non-cost reasons. Beneficiaries reporting food insecurity, poor functional status, and lack of understanding of the Part D benefit were more likely to report both types of medication nonadherence after adjustment for sociodemographic factors. Beneficiaries receiving the Low-Income Subsidy had lower odds of reporting cost-related but greater odds of reporting non-cost-related medication nonadherence. These findings suggest that non-cost-related sources of medication nonadherence, such as beneficiary preferences or beliefs, understanding of their health situation or insurance coverage, and ability to fill a prescription, are significant contributors to overall nonadherence. Non-cost-related medication nonadherence should be considered alongside recent changes to the Part D benefit and in future Part D Centers for Medicare and Medicaid Services (CMS) Innovation Center models, such as the proposed Medicare $2 Drug List Model, in order to maximize the impact of these initiatives.