To the Editor: Between 1995 and 2006, the 30-day hospital RSMR for older Medicare patients with AMI showed a significant decrease in between-hospital variation.1 The annual median (interquartile range) for AMI discharges per hospital decreased from 33 (12-76) in 1995 to 22 (7-70) in 2006. An earlier study2 showed that the hierarchical generalized linear model shrank standardized hospital rates toward the average US observed rate, largely at hospitals with fewer than 25 AMI cases. The majority of reduction in interhospital variation in RSMRs between 1995 and 2006 appears more attributable to marked decreases in the number of AMI cases per hospital than to more uniformity in hospital care.
Blumberg MS. Hospital Mortality in Acute Myocardial Infarction. JAMA. 2010;303(2):132-134. doi:10.1001/jama.2009.1971