Hospital quality measures do not fully account for the variation in hospital death rates for heart attack patients

Jul 4 2006

Hospital quality measures do not fully account for the variation in hospital death rates for heart attack patients, according to a study in the July 5 issue of Journal of the American Medical Association.

As part of the national effort to improve hospital quality, the Centers for Medicare & Medicaid Services (CMS) and the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) monitor and publicly report hospital performance on acute myocardial infarction (AMI – heart attack) "core" process measures approved by the Hospital Quality Alliance, according to background information in the article. Although the CMS/JCAHO process measures are considered indicators of quality of AMI care, little is known about how these measures track with each other. And the degree to which process measure performance conveys meaningful information about short-term death rates remains unclear.

Elizabeth H. Bradley, Ph.D., of the Yale University School of Medicine, New Haven, Conn., and colleagues used data from the National Registry of Myocardial Infarction (NRMI) and CMS to determine the correlations among AMI process measures and the association between hospital performance on process measures and hospital-specific, risk-standardized, 30-day death rates, derived from Medicare claims data. The researchers used 2002-2003 data from 962 hospitals participating in the NRMI and used information on AMI patients aged 66 years or older.

The researchers found moderately strong correlations between beta-blocker use at admission and discharge, aspirin use at admission and discharge, and angiotensin-converting enzyme (ACE) inhibitor use, and weaker, but statistically significant, correlations between these medication measures and smoking cessation counseling and time to reperfusion therapy measures. Some process measures were significantly correlated with risk-standardized, 30-day death rates but together explained only 6.0 percent of hospital-level variation in risk-standardized, 30-day death rates for patients with AMI.

"This finding suggests that a hospital's short-term mortality rates after AMI cannot be reliably inferred from performance on the publicly reported process measures. Our results highlight that the current process measures provide information that is complementary to, but not redundant with, a measure of 30-day mortality," the authors write.

"In conclusion, although the core measures are important in pursuing improved AMI outcomes, they capture in aggregate only a small proportion of the hospital-level variation in short-term 30-day mortality rates. Until additional process measures are developed that explain more of the variation, reporting not only the current core measures but also short-term risk-standardized mortality rates is a reasonable approach to characterize hospitals' overall quality of care," the researchers write.