Rush University Medical Center in Chicago says the Centers for Medicare & Medicaid Services (CMS) has miscalculated hospitals star ratings since they were first released in 2016, according to an article on the Crains Detroit Business  website.

Rush found that instead of evenly weighting the eight measures in the safety of care group, the CMS' star ratings formula relied heavily on one measure — PSI-90 — for the first four releases of the ratings and then complication rates from hip and knee replacements for the latest release, the article said.

The single measure accounted for about 98 percent of a hospital's performance in the safety group, according to Rush.

The statistical model the CMS uses, called latent variable modeling, isn't appropriate for measuring clinical outcomes, said David Levine, senior vice president of advanced analytics and informatics at Vizient. "We have expressed our deep concerns about this methodology because it changes the weight every time — that doesn't really make sense," he said in the article.

Read the article.