Hospital mortality from acute myocardial infarction has been modestly reduced after introduction of thrombolytics and aspirin: Results from a new analytical approach

The objective of this study was to investigate how the introduction of thro mbolytics and aspirin has affected hospital mortality (case fatality) among patients with acute myocardial infarction. The study design was the applic ation of the therapeutic effects found in the clinical trials in a nonselec ted myocardial infarction population characterized in detail. The study too k place in health region 1 in Norway, population 850,000, and subjects were all patients hospitalized and discharged, alive or dead, with a diagnosis of acute myocardial infarction in the 10 hospitals in the region over a per iod of 2 months. The main outcome measures were deaths in hospital and esti mation of expected hospital mortality without thrombolytics or aspirin, wei ghing and evaluating the effects of delay of different lengths from onset o f symptoms to admission, different ages, and different electrocardiogram ch anges. We found that 32% of the patients received thrombolytics, and 72% re ceived aspirin. Hospital mortality was 18.1% compared with 20.6% had neithe r of the treatments been administered, implying that the two regimens had r educed mortality by 12%, aspirin contributing about four fifths and thrombo lytics one fifth. We conclude that hospital mortality in a nonselected myoc ardial infarction population has been reduced to moderate extent since the introduction of thrombolytics and aspirin. The effects observed in clinical trials are not translated into epidemiologically documented reduction in m ortality, as the optimal conditions are found only in a proportion of the p atient groups constituting a nonselected myocardial infarction population, (C) 1999 Elsevier Science Inc.