Variation in Postoperative Outcomes Across Federally Designated Hospital Star Ratings
Authors: Diaz Adrian , Harbaugh Calista , Dimick Justin B. , Kunnath Nicholas , Ibrahim Andrew M. 
Published: June 2024

Importance

Despite widespread use to guide patients to hospitals providing the best care, it remains unknown whether Centers for Medicare &amp;amp; Medicaid Services (CMS) hospital star ratings are a reliable measure of hospital surgical quality.

Objective

To examine the CMS hospital star ratings and hospital surgical quality measured by 30-day postoperative mortality, serious complications, and readmission rates for Medicare beneficiaries undergoing colectomy, coronary artery bypass graft, cholecystectomy, appendectomy, and incisional hernia repair.

Design, Setting, and Participants

This cohort study evaluated 100% Medicare administrative claims for nonfederal acute care hospitals with a CMS hospital star rating for calendar years 2014-2018. Data analysis was performed from January 15, 2022, to April 30, 2023. Participants included fee-for-service Medicare beneficiaries aged 66 to 99 years who underwent colectomy, coronary artery bypass graft, cholecystectomy, appendectomy, or incisional hernia repair with continuous Medicare coverage for 3 months before and 6 months after surgery.

Exposure

Centers for Medicare &amp;amp; Medicaid Services hospital star rating.

Main Outcomes and Measures

Risk- and reliability-adjusted hospital rates of 30-day postoperative mortality, serious complications, and 30-day readmissions were measured and compared across hospitals and star ratings.

Results

A total of 1 898 829 patients underwent colectomy, coronary artery bypass graft, cholecystectomy, appendectomy, or incisional hernia repair at 3240 hospitals with a CMS hospital star rating. Mean (SD) age was 74.8 (7.0) years, 50.6% of the patients were male, and 86.5% identified as White. Risk- and reliability-adjusted 30-day mortality rate decreased in a stepwise fashion from 6.80% (95% CI, 6.79%-6.81%) in 1-star hospitals to 4.93% (95% CI, 4.93%-4.94%) in 5-star hospitals (adjusted odds ratio, 1.86; 95% CI, 1.73-2.00). There was wide variation in the rates of hospital mortality (variation, 1.89%; range, 2.4%-16.2%), serious complications (variation, 1.97%; range, 5.5%-45.1%), and readmission (variation, 1.27%; range, 9.1%-22.5%) across all hospitals. After stratifying hospitals by their star rating, similar patterns of variation were observed within star rating groups for 30-day mortality: 1 star (variation, 1.91%; range, 3.6%-12.0%), 2 star (variation, 1.86%; range, 2.8%-16.2%), 3 star (variation, 1.84%; range, 2.9%-12.3%), 4 star (variation, 1.76%; range, 2.9%-11.5%), and 5 star (variation, 1.79%; range, 2.4%-9.1%). Similar patterns were observed for serious complications and readmissions.

Conclusion and Relevance

Although CMS hospital star rating was associated with postoperative mortality, serious complications, and readmissions, there was wide variation in surgical outcomes within each star rating group. These findings highlight the limitations of the CMS hospital star rating system as a measure of surgical quality and should be a call for continued improvement of publicly reported hospital grade measures.