Designing And Evaluating Prescription Drug Models

From 2021 to 2023, the Center for Medicare and Medicaid Innovation, also known as the CMS Innovation Center, tested the Part D Senior Savings (PDSS) model, which lowered Medicare Part D insulin out-of-pocket costs to a maximum of $35 for beneficiaries in model-participating plans. It was the Innovation Center’s largest prescription drug model test in terms of the number of participants. RAND Health evaluated this model for the Innovation Center, and, in September 2025, we published our final PDSS evaluation report.

The goal of this article is to apply our evaluation experiences to offer five design and evaluation considerations for future prescription drug models that the Innovation Center is interested in designing and testing. We discuss implications of each consideration for key stakeholders based on our interviews with participating plans, manufacturers, and beneficiaries.