Fig. 1 CMS programs that contribute to the Star System. Source:


Published 2/1/2018
Andrew Krause, MD; Zain Sayeed, MD, MHA; Jasmine Saleh, MD, MPH; Muhammad T. Padela, MD, MSc; Khaled J. Saleh, MD, MSc, FRCS(C), MHCM, CPE

The CMS Overall Hospital Quality Star Rating System

In July 2016, the U.S. Centers for Medicare and Medicaid Services (CMS) released Overall Hospital Quality Star Ratings (Star System) for more than 3,000 hospitals in the United States. Subsequent ratings were released in October and December 2016.

The Star System uses the CMS five-star scale to rate hospitals by summarizing existing publicly reported quality measures (Fig. 1). This article discusses the impact star ratings have for various hospitals across the country.

Key findings
Results of the Star System were publicly released three times during 2016 (July, October, and December). Fig. 2 shows the Star System results for each of the three releases. The following key points have been ascertained from these findings:

  • Hospitals with fewer beds were able to achieve a four-star or higher rating more frequently than larger hospitals (Fig. 3). For example, specialty hospitals received 41.1 percent of the five-star ratings, but accounted for only 2.2 percent of the 3,591 hospitals in the study.
  • Analysis of the OHQSR results from July 2016 revealed that a ≥ 4 star rating was given to 15.8 percent of major teaching hospitals, 18.8 percent of other teaching hospitals, 30.2 percent of community hospitals, 33.3 percent of critical access hospitals, and 87.3 percent of specialty hospitals.
  • Profit status appears to influence the Star System ratings. Prior data demonstrated that
    67.9 percent of 125 five-star rated hospitals were given to for-profit institutions, whereas nonprofit and public hospitals received 24.1 percent and 8.0 percent of five-star ratings, respectively. On the opposing end of the spectrum, 34.2 percent of 76 one-star rated hospitals were given to for-profit hospitals, while nonprofit and public hospitals received 51.3 percent and 14.5 percent, respectively. Therefore, for-profit institutions had a higher frequency of superior ratings.
  • Lower mortality and readmission rates are associated with higher star ratings. Four- and five-star rated hospitals were more likely to be small, nonteaching, and located in small rural towns. Studies have also revealed that hospitals in the South and Midwest have higher star ratings than those in the Northeast and West.
  • According to one study, lower rates of complications from joint replacements, central line-associated infections, postsurgical deep vein thrombosis, and a composite of all serious infections were significantly correlated with higher HCAHPS (Hospital Consumer Assessment of Healthcare Providers and Systems) survey (score 0-10).
  • Another study suggested that hospitals with a higher ratio of nurses to patient-days were more likely to receive a higher overall global rating on the HCAHPS survey. A smaller percentage of patients in for-profit hospitals gave a rating of ≥ 9/10 compared to patients in either private or public nonprofit hospitals (59.1 percent versus 64.8 percent and 65.4 percent, respectively; P < 0.001 for both comparisons).
  • A comparison of outcomes and costs for advanced laparoscopic abdominal surgery showed that high-star hospitals (HSH) had a lower rate of intensive care unit admissions compared to low-star hospitals (LSH) (2.6 percent and 5.0 percent, respectively) The mean cost of stay was $7,866 at HSHs and $8,708 at LSHs. Serious morbidity for colorectal surgery was lower at HSHs than at LSHs (2.2 percent and 2.9 percent, respectively, P = 0.002). HSHs may have better resource utilization compared to lower-rated hospitals and that will likely have a positive impact on their Star System ratings.

Issues with the Star System
Concerns that the Star System does not accurately reflect each hospital's performance led Congressional representatives to lobby for changes in methodology prior to the release of the ratings. The fact that major referral centers received only one or two stars has called the validity of the rating system into question. Clinical experts recognize that large referral centers provide superior specialty care even if their Star System rating does not reflect the center's reputation. They also realize that current calculations do not factor in the complexity of conditions treated at teaching hospitals or differences in patient populations.

Private, smaller, and nonteaching hospitals may receive higher star ratings than large referral centers because they treat less complex conditions and have more patients in higher socioeconomic classes (Fig. 4).

Previous studies have reported that readmission rates are higher among patients from lower socioeconomic backgrounds. Although the Star System does include risk-adjusted quality measures for clinical comorbidities, it does not include additional adjustments for sociodemographic characteristics. CMS is working with the National Quality Forum to evaluate the influence of socioeconomic status on quality measures.

Fig. 1 CMS programs that contribute to the Star System. Source:
Fig. 2 Distribution of results for the Star System in 2016 on the CMS Five-Star Scale. Source:
Fig. 3 Percentage of hospitals receiving a four-star or higher ranking in July 2016, based on the number of beds. Source:
Fig. 4 Average CMS Star Rating score for various hospital characteristic comparisons, based on July 2016 rankings. Source:

Because 40 percent of the hospitals that received a five-star rating in the July 2016 did not report data from all seven categories, hospitals that report more measures may be negatively affecting their Star System score. The specific measures that each institution reports remain highly variable. A standardized reporting process of universal metrics may enable more valid comparisons and higher participation from institutions nationally.

Hospitals can use the information and analysis in this article to help develop strategies to improve their ratings. Currently, private, smaller, nonteaching, and specialty hospitals seem to have an edge over large, public, teaching hospitals.

CMS will continue to adapt and improve the current calculation algorithm based on feedback received after each published rating.

Andrew Krause, MD, is a member of the department of internal medicine at the Detroit Medical Center; Zain Sayeed, MD, MHA, and Muhammad T. Padela, MD, MSc, are members of the department of orthopaedics at the Detroit Medical Center; Jasmine Saleh, MD, MPH, is the director and cofounder of Global Health Conscious NFP; Khaled J. Saleh, MD, MSc, FRCS(C), MHCM, CPE, is the executive-in-chief of orthopaedics at the Detroit Medical Center.

Editor's note: This article is the second of a three-part series detailing the CMS Overall Hospital Quality Star Rating. Part one appeared in the January issue of AAOS Now; part three will appear in the March issue.


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