Consequences of forgoing prescription drug subsidies among low-income Medicare beneficiaries with diabetes.

Objective: The objective is to estimate the take-up of the Medicare Part D Low-Income Subsidy (LIS) among Medicare beneficiaries with diabetes and examine differences in out-of-pocket costs and prescription drug use between LIS enrollees and LIS-eligible non-enrollees. The LIS reduces out-of-pocket drug costs for low-income beneficiaries; however, not all LIS-eligible individuals are enrolled. Take-up of the LIS, and consequences of forgoing this benefit among beneficiaries with diabetes, remains unknown.

Data Sources: Health and Retirement Study linked to Medicare administrative data from 2008 to 2016.

Study Design: We conducted two analyses among beneficiaries with diabetes. First, we estimated LIS take-up stratified by income (≤100% of the Federal Poverty Level [FPL] and >100% to ≤150% of FPL). Second, to assess the consequences of forgoing the LIS among near-poor beneficiaries (incomes >100% to ≤150% of FPL), we conducted propensity score-weighted regression analyses to compare out-of-pocket costs, the prescription drug use, and cost-related medication non-adherence among LIS enrollees and LIS-eligible non-enrollees.

Data Collection/data Extraction: N/A.

Principal Findings: Among Medicare beneficiaries with diabetes, 68.1% of those with incomes >100% to ≤150% of FPL received the LIS, while 90.3% with incomes ≤100% of FPL received the LIS. Among near-poor beneficiaries, LIS-eligible non-enrollees incurred higher annual out-of-pocket drug spending ($518; 95 [in USD]% CI: $370 [in USD], $667 [in USD]; p < 0.001), filled 7.3 fewer prescriptions for diabetes, hypertension, and hyperlipidemia drugs (95% CI: -11.1, -3.5; p < 0.001), and were 8.9 percentage points more likely to report skipping drugs due to cost (95% CI: 0.3, 18.0; p = 0.04), all compared to LIS enrollees.

Conclusions: Despite providing substantial financial assistance with prescription drug costs, the LIS is under-utilized among beneficiaries with chronic conditions requiring routine medication use. As policy makers discuss Part D reforms to address rising out-of-pocket drug costs, they should consider strategies to increase participation in existing programs that alleviate cost burdens among low-income Medicare beneficiaries.