CMS outlines the methodology behind its five-star hospital ratings

CMS held a webinar on May 12 explaining the methodology and upcoming changes to its controversial five-star hospital ranking system. Under the ranking system, hospitals would receive more stars for better compliance with a set of measures that focus on mortality, safety, hospital readmissions, and the timeliness and effectiveness of care. Prior to the webinar, several groups have argued that the star ranking system is too simplified to show true quality and reported difficultly replicating CMS’s methodology in testing the five-star rating system.

Some of the changes include the elimination of 14 voluntary measures falling under the “effectiveness of care” and “timeliness of care” categories. Measures for 20-day mortality and readmission coronary bypass grafting were added in April, with two colonoscopy measures to be added in July.

One of the webinar’s speakers was Arjun Venkatesh, MD, director of quality and safety research and strategy at the Yale University School of Medicine. He said that the five guiding principles behind the hospital star ratings simplicity/accessibility, inclusivity, scientific rigor, stakeholder engagement and consistency. The ratings methodology itself comprises of five steps:

1.    CMS select measures
2.    Measures are grouped into respective categories, such as safety, mortality or patient experience
3.    Group scores are calculated based on latent variable models
4.    A weighted summary score is generated for each hospital
5.    A final star rating is awarded

In addition to the Hospital Compare data, CMS will also start providing hospital-specific reports with additional details, such as individual standardized measure scores. The release of the star system has been postponed until July. Click here to see the CMS webinar slides.