Analysis of the Impact of an Insulin Savings Model Among Medicare Part D Beneficiaries and Plan Sponsors

Background: An estimated one in every three Medicare beneficiaries have diabetes, and over 3.3 million Medicare beneficiaries currently use at least one form of insulin. On average, insulin retail prices can range anywhere between $90 to $1300 per package. Additionally, Medicare beneficiaries may enter various coverage phases throughout a plan year, resulting in variable prices and in some cases, significantly higher copays on insulin from one month to the next. A higher patient copay during the coverage gap phase has been associated with reduced adherence, which can lead to disease progression and worse outcomes. In 2021, the Part D Senior Savings Model was introduced to offer a benefit design that includes predictable member copays during all the coverage phases. Methods: This study was designed as a retrospective analysis comparing post-implementation prescription claims from 2021 to pre-implementation claims from 2020. Inclusion criteria consisted of members enrolled in a Medicare Advantage Plan with a Senior Savings Model benefit design during 2021 and a pharmacy benefit manager aligned model insulin list. Exclusions consisted of members enrolled in a Medicare Prescription Drug Plan (PDP), a plan with a customized insulin drug list, and/or a member receiving Low Income Subsidy. The primary objective was to analyze changes in the number of model insulin utilizers among Medicare Part D beneficiaries and plan sponsors enrolled in the Senior Savings Model during the 2021 plan year. Secondary objectives were to evaluate other changes in model insulin utilization, including days supply and adherence. A financial analysis was also performed looking at changes among model insulins in member copay, total net cost, and total gross cost. Descriptive statistics were used for all study variables. Categorical data, including changes in the number of model insulin utilizers, was analyzed using a chi-square test to identify a P-value with a significance threshold set at 0.05. Quantitative data was evaluated through an unequal variances t-test. Results: The Senior Savings Model was found to significantly reduce member copay amounts, but did not result in adverse utilization of model insulins. The number of members who were optimally adherent did not change, but there was a slight reduction seen in overall adherence. Conclusion: Our findings would suggest that the SSM can improve member experience by reducing member copays but may not significantly impact adherence metrics.