This paper complements the publication “Potential IRA Interactions with Medicare Part D Risk Adjustment: Model Considerations.” In this paper, which was also commissioned by Pharmaceutical Research and Manufacturers of America, we explore potential impacts to plans resulting from calibrating the 2025 Part D risk adjustment model using data from more recent time periods. The Centers for Medicare and Medicaid Services had used earlier data for calibration, rather than 2021 or 2022 expenditure data. We discuss the following: 

• Data considerations for each of the periods available for use in calibrating the 2025 RxHCC model
• Areas of impact
• Caveats and limitations

This paper was commissioned by PhRMA.