How the Hospital Compare overall rating is calculated
The Hospital Compare overall rating summarizes up to 57 quality measures across seven areas of quality into a single star rating for each hospital. Once reporting thresholds are met, a hospital’s overall rating is calculated using only those measures for which data are available. This may include as few as 9 or as many as 57 measures. The average is about 39 measures. Hospitals report data to the Centers for Medicare & Medicaid Services - Opens in a new window through the Hospital Inpatient Quality Reporting (IQR) Program - Opens in a new window Exit Disclaimer - Opens in a new window and the Hospital Outpatient Quality Reporting (OQR) Program - Opens in a new window Exit Disclaimer - Opens in a new window. Star ratings are not calculated for Veterans Health Administration (VHA) hospitals.
The methodology uses a statistical model known as a latent variable model. Seven different latent variable models are used to calculate scores for seven groups of measures.
- Safety of Care
- Patient Experience
- Effectiveness of Care
- Timeliness of Care
- Efficient Use of Medical Imaging
A hospital summary score is then calculated by taking the weighted average of these group scores. If a hospital is missing a measure category or group, the weights are redistributed amongst the qualifying measure categories or groups.
Finally, the overall rating is calculated using the hospital summary score.
Only hospitals that have at least three measures within at least three measure groups or categories, including one outcome group (mortality, safety, or readmission), are eligible for an overall rating. Not all hospitals report all measures. Therefore, some hospitals may not be eligible for an overall rating.
The comprehensive methodology report - Opens in a new window Exit Disclaimer - Opens in a new window provides additional detail on the methodology used to calculate the Hospital Compare overall rating.
National distribution of overall star ratings
The following table shows the national distribution of the overall star rating based on December 2017 results.
|Overall Rating||Number of Hospitals (N=4,579, %)|
|5 stars||337 (7.36%)|
|4 stars||1155 (25.22%)|
|3 stars||1187 (25.92%)|
|2 stars||753 (16.44%)|
|1 star||260 (5.68%)|
|N/A[2 view 2016 fact sheets- Opens in a new window]||887 (19.37%)|
The methodology for calculating the overall ratings was developed with input from stakeholders and members of the public. Detailed information on the methodology is available on QualityNet - Opens in a new window External Link icon.
Questions about the Hospital Compare overall rating may be submitted to: email@example.com.