The association of myocardial infarction process of care measures and in-hospital mortality: a report from the NCDR®

Background: The Center for Medicare and Medicaid Services (CMS) publicly reports "core process of care measures" along with 30-day mortality rates for patients with acute myocardial infarction; the American College of Cardiology/American Heart Association has a similar but expanded set of performance measures.

Methods: We sought to determine whether hospital-level adherence with these process performance measures was associated with risk-adjusted in-hospital mortality among 96,340 ST-segment elevation myocardial infarction (STEMI) and 145,832 non-STEMI (NSTEMI) patients in the National Cardiovascular Data Registry® ACTION Registry-Get With the Guidelines™ admitted from January 2007 to March 2011 from 372 US sites. Hospitals were grouped based on risk-adjusted in-hospital mortality: low (20%), middle (60%), and high mortality (20%).

Results: The mean (SD) mortality from low to high hospital mortality groups for STEMI was 4.9% (0.9%), 5.8% (0.3%), and 7.0% (0.5%); and that for NSTEMI was 3.3% (0.2%), 4.0% (0.2%), and 4.9% (0.3%). Adherence to individual process measures was high, with composite measure adherences exceeding 88%. Composite adherence for both CMS and American College of Cardiology/American Heart Association performance measures was inversely associated with risk-adjusted hospital mortality. However, the association was low for STEMI hospitals and not significant for NSTEMI hospitals. Variation tended to be higher for CMS measures for higher-mortality hospitals.

Conclusions: Although process performance was associated with hospital mortality, the association was low for STEMI and nonsignificant for NSTEMI hospitals, thus supporting the need to measure complementary metrics of acute myocardial infarction quality of care.