Population-wide mortality trends among patients hospitalized for acute myocardial infarction: the Ontario experience, 1981 to 1991

Abstract

Objectives: This study attempted to determine population-based trends in in-hospital patient fatality from acute myocardial infarction.

Background: The in-hospital prognosis for patients with acute myocardial infarction should be improving as a result of adoption of treatments proved in randomized trials (e.g., thrombolytic, beta-adrenergic blocking and anticoagulant agents and aspirin). However, all trials are subject to selection biases, eligibility is limited for some therapies, and proved therapies may be underused even among eligible patients.

Methods: Using administrative data from all general hospitals in Ontario, Canada, we analyzed 17,489, 17,839, 18,393, 18,794, 18,716 and 19,748 records of patients with a primary discharge diagnosis of myocardial infarction for fiscal years 1981, 1983, 1985, 1987, 1989 and 1991, respectively.

Results: After age and gender adjustment, the overall relative reduction in in-hospital case fatality rates for the 10-year period was 26.9% (99% confidence interval [CI] 26.8% to 26.9%), corresponding to an absolute reduction of 6% (99% CI 5.6% to 6.4%). Age- and gender-standardized case fatality rate decreased from 22.3% in 1981 to 21.4% in 1985, followed by a highly significant decline to 16.3% in 1991. On the basis of the relation of comparative mortality to days of hospital stay, declining mortality was not an artifact of decreasing length of stay.

Conclusions: There have been encouraging improvements in survival after acute myocardial infarction over the past 6 years. Further improvements may require development of new therapies that can be more widely applied to this patient population.