Dual-eligible patients impact hospitals' star ratings, but blanket methodology adjustments aren't the answer, researchers say

Although hospitals treating greater proportions of dual-eligible patients again received lower star rating scores in 2021, potential policy decisions to adjust for these complex patients will need to take a closer look at the underlying measure groups driving lower, equal and in some cases higher quality scores for hospitals, the authors of a new Health Affairs analysis advised.  

The overall Centers for Medicare & Medicaid Services (CMS) star rating scores are publicly reported on the Care Compare website and combine five quality measure groups: mortality, readmission, patient experience, safety, and timely and efficient care.

By comparing the average scores of over 3,000 facilities for each of the five measure groups, policy researchers found that worse scores weren’t a constant across hospitals with higher portions of dual-eligible patients (those eligible for both Medicare and Medicaid).

Specifically, while readmission and patient experience scores were worse among hospitals with the highest proportion of dual-eligibles, the analysis also found that these hospitals scored higher on average across CMS’ mortality measures in 2021. Performances across the remaining two measures were “generally similar” with a slight edge to hospitals with very small proportions of dual-eligibles.

“Adjusting overall star ratings for dually eligible proportion assumes that caring for more dually eligible patients is part of the causal pathway that leads to worse performance on all the underlying star ratings measures, which is untrue,” researchers wrote in the journal. “Yet for certain measure groups, such as readmissions, dually eligible proportion may be part of this causal pathway, explaining why hospitals with greater proportions of dually eligible patients perform worse on readmissions.”

Alongside serving as an argument against blanket adjustments for hospitals’ dual-eligible burden, the findings also offer insights on how results for certain measures—for instance, mortality—are influenced by existing adjustments and social risk factors, they continued.

“Although dually eligible patients have significantly higher in-hospital, 30-day, and one-year mortality rates than non–dually eligible patients, [better mortality scores are] likely explained by the fact that dually eligible patients tend to suffer from more comorbidities than non–dually eligible patients,” researchers wrote.

“The risk-adjustment methodology in the mortality measures adjusts for a large and diverse group of comorbidities, and including an additional variable for dual eligibility status at the patient level is unlikely to substantially increase the predicted probability of mortality for dually eligible patients when a robust risk-adjustment model is already present,” they wrote.

The researchers’ analysis pulled data from the October 2020 Care Compare data set to calculate 2021 star ratings, as well as from the 2018 American Hospital Association Annual Survey Database for hospital characteristics and the 2019 Medicare Beneficiary Summary File and Medicare Provider Analysis and Review File to determine program eligibility. These datasets allowed the researchers to gauge recent changes to CMS’ star ratings methodology that weren’t in effect for prior studies of dual-eligible-serving hospitals.

Additionally, their analysis reviewed a proposed methodology change briefly considered by CMS to stratify hospitals by proportion of dual-eligible patients when calculating readmission group scores.

Stratification into quintiles was adopted by CMS in fiscal-year 2019 for calculating payments but didn’t make it past the proposal stage for public quality reporting due to concerns that the adjustments would hamper patients’ decision-making.

The researchers found that stratifying hospitals into quintiles for the readmission measure group, as proposed, would have seen 142 facilities gain a star, 89% of which were sorted into the highest (more dual-eligibles) quintile. It would also have caused 126 to lose a star, with only one of those hospitals coming from the highest quintile.

Put another way, stratification caused 20% of hospitals in the highest quintile to gain a star and 11% in the lowest to lose a star.

“Adjusting public reporting tools such as star ratings for social risk factors is ultimately a policy decision, and views on the appropriateness of accounting for factors such as proportion of dually eligible patients are mixed, depending on the organization and stakeholder,” the researchers wrote.

“Nevertheless, continued evaluation of disparities or differences in performance in star ratings should be an ongoing area of work for CMS.”