How Does CMS Calculate the Hospital Star Rating?

CMS first released the Hospital Star Ratings in 2017 in an attempt to make it easier for patients to judge a hospital’s quality of care.

The star rating calculation was simplified in 2021 and now is calculated in 10 steps.

1. Hospitals submit data to CMS quality programs

2. CMS identifies which measures will be used to calculate the score and for what time frames of data
3. CMS standardizes the measure scores
4. Put those measures into groups
5. CMS calculates the measure group score using a simple average
6. The group scores are given a weight
7. Hospitals are excluded or their score is re-weighted depending on the number of measures submitted
8. Hospitals are put into one of three peer groups based on the number of measures they submitted
9. Within the peer groups, scores are split into 5 groups using the k-means clustering method
10. Whichever group your score puts you in becomes your star rating

The video below will outline the 10 steps for calculating the Hospital Star Rating.

Download the excel sheet for measures and date timeframes used for the Star Ratings calculation.