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 thrombolytics and aspirin has affected hospital mortality (case fatality) among patients with acute myocardial infarction. The study design was the application of the therapeutic effects found in the clinical trials in a nonselected myocardial infarction population characterized in detail. The study took 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 period of 2 months. The main outcome measures were deaths in hospital and estimation of expected hospital mortality without thrombolytics or aspirin, weighing and evaluating the effects of delay of different lengths from onset of symptoms to admission, different ages, and different electrocardiogram changes. We found that 32% of the patients received thrombolytics, and 72% received aspirin. Hospital mortality was 18.1% compared with 20.6% had neither of the treatments been administered, implying that the two regimens had reduced mortality by 12%, aspirin contributing about four fifths and thrombolytics one fifth. We conclude that hospital mortality in a nonselected myocardial 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 mortality, as the optimal conditions are found only in a proportion of the patient groups constituting a nonselected myocardial infarction population, (C) 1999 Elsevier Science Inc.