The answer is ‘yes’ according to a paper by Borrelli et al. (2025). The authors use annual Medicare Star Rating health plan performance for Medicare Advantage-Part D (MAPD) plans over the past decade (2015 to 2024). They find that:
For plans achieving at least 4 stars on the medication adherence measures, 70%-74% of them also achieved at least a 4-staroverall 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.
Star ratings are important because they impact MA-PD plan rebates:
Plans achieving an overall summary rating of 4.5 or 5.0 stars receive a 70% rebate from CMS, those with 3.5 or 4.0 stars receive a 65% rebate, and plans with less than 3.5 over all stars receive a 50% rebate. Additionally, health plans that receive at least a 4.0-star overall rating qualify for a 5%quality bonus payment (QBP). In 2024, Medicare paid more than $11.8 billion in QBP to MAPD plans, with the average QBP per enrollee ranging from $265 to $516, depending on the specific plan
There are two separate pathways through which medication adherence quality measure impact overall rating. The first is that performance on individual quality measures. A previous paper I wrote (Sussell et al. 2017) on the impact of improved diabetes care on Medicare Advantage Part C plan star ratings found that improvements to any one or two quality measures had a modest impact on overall star ratings (because there are many other quality measures).
A second pathway, is that the medication adherence quality metric may be a proxy for overall MAPD plan quality. A plan may be good on all fronts. Thus, the relationship between medication adherence and overall star ratings could be correlational in nature. Good MAPD process may lead to improved quality across multiple fronts.
Nevertheless, the finding that improved adherence quality measures is correlated with overall quality is a useful finding.
