Effects of the Part D Senior Savings Model on racial and ethnic disparities in healthcare costs.

Objective: The Centers for Medicare & Medicaid Services tested the Part D Senior Savings Model ("PDSS Model") in 2021, capping monthly out-of-pocket (OOP) insulin costs at $35. Diabetes disproportionately affects racial/ethnic minorities compared to their non-Hispanic White (White) counterparts, so this study compared the changes in racial/ethnic disparities in healthcare costs among insulin users between Medicare and non-Medicare populations in 2021.

Methods: This study analyzed the Medical Expenditure Panel Survey (2020-2021). The intervention group comprised Medicare beneficiaries aged ≥65, while the comparison group included a near-elderly non-Medicare population. The study outcomes included annual OOP/total costs in 2021 dollars for insulin, medication, health services (medical), and overall healthcare. A difference-in-differences-in-differences approach was employed to assess the PDSS Model's effects between White and each racial/ethnic minority group.

Results: The weighted sample included 1,056,386 insulin users (53.89% intervention). In 2020, among the intervention group, non-Hispanic Black (Black) and Hispanic had similar or higher insulin costs than White patients. Black-White differences in OOP insulin costs were lowered more among the intervention group (cost ratio [CR] = 0.12, 95% confidence interval = 0.06-0.22) than the comparison group. Black-White differences in OOP costs for medication, health services, and overall healthcare widened more among the intervention group by 61-64%. These patterns were not seen for other racial/ethnic disparities.

Conclusions: Among insulin users, Black may have benefited more from the PDSS Model than White patients, which may be associated with enhanced insulin access and lower needs for other healthcare. Future studies should examine the long-term and heterogeneous impact of the PDSS Model.