NEWS | May 25, 2018

Heart attack mortality ratings can misrepresent performance of high-tech hospitals

Study reveals problem in the federal model for comparing hospital death rates

(SACRAMENTO, Calif.)

An apparent flaw in the formula for assessing 30-day mortality following heart attacks may compromise quality ratings for hospitals that provide advanced cardiovascular care, new research on Center for Medicare & Medicaid Services (CMS) quality measures finds.

Patrick Romano Patrick Romano

An important factor in assessing hospital quality, mortality rates are estimated by comparing the number of deaths at each hospital within 30 days of admission for certain conditions with the number of deaths expected based on national data.

While these rates are adjusted for patient characteristics that may make death more likely, the study revealed one odd adjustment. Patients diagnosed with atherosclerosis, or arteries narrowed by plaques, somehow had lower expectations of death following a heart attack. As a result, hospitals that diagnose atherosclerosis more frequently may get worse ratings on the CMS Hospital Compare website and elsewhere.

An atherosclerosis diagnosis was more common in hospitals offering percutaneous coronary interventions (PCI), a potentially life-saving approach for treating heart disease without surgery. Hospitals without PCI, on the other hand, diagnosed atherosclerosis less often and their patients were assigned a higher risk of death, inflating their ratings on Hospital Compare.

Published in the Journal of the American Heart Association, the outcomes lead the researchers to recommend eliminating the “atherosclerosis diagnosis” adjustment from the CMS model for 30-day mortality risk adjustment.

“Hospitals capable of diagnosing atherosclerosis should not be punished for doing so due to a quirk in the model rather than actual performance, especially since PCI has been shown to improve outcomes for some patients with heart disease,” said co-author Patrick Romano, professor of general internal medicine at the Center for Healthcare Policy and Research at UC Davis.

The study is one in a series from Romano and University of Pennsylvania colleagues on hospital ratings. The current study involved over 400,000 older Medicare beneficiaries hospitalized for heart attacks in the U.S. between 2009 and 2011. Details of their evaluation showed:

  • Patients admitted to PCI hospitals were significantly more likely to be diagnosed with atherosclerosis than those in non-PCI hospitals — 87 percent versus 70 percent.
  • An atherosclerosis diagnosis was associated with a 42 percent reduction in the odds of death. 
  • Without the atherosclerosis adjustment, the authors estimated that 72 of the 100 largest PCI hospitals would have received better rankings, and the estimated number of lives saved by PCI hospitals would have been 7,296 instead of 4,311, a 62 percent increase.

Accuracy in hospital ratings is important, according to Romano, because they help consumers and other stakeholders compare hospitals and make health care decisions. They are also used to set federal financial rewards or penalties for hospitals.

“Ratings help promote transparency and accountability in health care, but hospitals need to be fairly benchmarked,” Romano said. “Developers of risk-adjustment models need to be careful about the factors they include.”

Additional researchers on the study were first author Bijan Niknam, Alexander Hill, Richard Ross and Orit Even-Shoshan with the Center for Outcomes Research at the Children’s Hospital of Philadelphia, and Alexander Arriaga, Paul Rosenbaum and senior author Jeffrey Silber of the University of Pennsylvania.

The study was funded by the Agency for Healthcare Research and Quality (grant R01HS023560).