The influence of medication adherence on Medicare Star Ratings: A decade-long analysis of health plan performance.

Background: The Medicare Star Ratings Program, managed by the Centers for Medicare & Medicaid Services, assesses Medicare health plan performance. This program consists of quality measures that evaluate plan performance for both Medicare Part C and Part D, including 3 key medication adherence measures.

Objective: To assess the potential relationship between performance on medication adherence measures and overall star rating performance for Medicare Advantage (MA) health plans.

Methods: An analysis was conducted using annual Medicare Star Rating health plan performance data from 2015 to 2024 to assess the impact of performance on medication adherence measures on health plan overall star rating. Numerical percentages were calculated to assess the rates of a health plan achieving at least a 4-star overall rating if they achieved 4 or more stars, as well as a 5-star rating on each medication adherence measure or composite measure.

Results: From 2015 to 2024, 4,213 health plan contracts received a star rating, of which 2,076 achieved at least a 4-star overall rating (49.3%). For plans achieving at least 4 stars on the medication adherence measures, 70%-74% of them also achieved at least a 4-star overall summary rating, depending on the specific measure. Among plans achieving 5 stars on any adherence measure, 85%-90% of them achieved at least a 4-star overall rating.

Conclusions: Assessing a decade of the Medicare Star Rating performance data showed that MA health plans that performed well on the medication adherence measures also had a high rate of achieving a 4-star overall rating. Future research should explore the interplay between medication adherence measures and other Medicare Star Rating criteria.