CMS hospital overall star ratings methodology flawed, Health Affairs says

The newly released star ratings from CMS may be confusing to patients and families thanks to the absence of many well-known hospitals that have been rated well by other agencies and what Health Affairs is calling a flawed methodology for calculating the results.

July saw the implementation of a new overall star rating system on the Centers for Medicare and Medicaid Services' Hospital Compare website. A series of 64 quality measurements from seven quality domains dictates a hospital's rating of between one and five stars, with the stated intention of the ratings being to "help patients and families learn about hospital quality, compare facilities side by side, and ask important questions about care quality," Health Affairs said in a blog post Monday.

The methodology's intention is for domain weight to reflect relative importance of a quality domain to patients. CMS has assigned 66 percent of the overall star rating to the domains mortality, readmission, and patient safety; these measure clinical outcomes such as whether a patient dies, contracts a hospital-acquired infection, or is readmitted to the hospital within 30 days of an inpatient stay. Other domains that focus on things like efficient use of medical imaging and timeliness of care carry less weight, the blog said.

[Also: Experience, nonprofit status mean high star ratings for Medicare Advantage contracts]

Despite the distribution of weight among these domains, CMS calculated and published star ratings for hospitals that did not have enough data to report on all domains; some had only enough to report on as few as three of them. Others had only enough data to support reporting on one domain. Moreover, when a hospital lacks sufficient data to report on one or more quality domains, the "weights" of the missing domains are redistributed to the domains that have enough data to be measured.

"The fewer the clinical outcome domains a hospital reports, the less that hospital's overall star rating is actually tied to performance on patient outcomes," Health Affairs said.

According to the July 2016 hospital compare data released, 40 percent of the 102 hospitals that received a five-star rating lacked the minimum data necessary to report on either mortality or readmissions, leading to "wide performance divide" hospitals that scored five stars.

[Also: Quantros study challenges reliability of CMS hospital star ratings]

Health Affairs said for the information provided by the star ratings to actually be meaningful and accurately reflect hospital quality, it has to make sense and, among hospitals with the same star rating, should be consistent.

"Higher star ratings should reflect better actual quality performance. Unfortunately, the CMS star ratings in their current form fail to meet this basic test and will do more harm than good to patients."

Twitter: @BethJSanborn