Medicare Advantage Star Rating Quality Gains Were Concentrated In A Narrow Set Of Clinical And Medication Measures, 2015–25

The Medicare Advantage Star Ratings program has operated for decades and directs billions of dollars in quality bonus payments, yet little is known about which measures have driven observed performance improvement over time. During the period 2015-25, most of the improvement in star ratings was concentrated in a small subset of clinically focused and medication-related measures, with nine measures accounting for more than one-third of observed gains. Medication reconciliation and medication therapy management showed the greatest improvement, while many access, preventive care, and patient experience measures showed little or no improvement. Patterns were consistent across both Part C and Part D, suggesting that gains were driven largely by medication management and other provider-led activities, rather than plan-specific responses to quality bonus incentives. Lower-performing contracts improved the most, whereas high-performing plans exhibited smaller measurable gains as a result of there being limited room for further improvement and longer measurement histories for some measures. Aligning incentives with measures that are both clinically meaningful and responsive to health plans' actions may promote more balanced quality improvement.