Background: Case fatality associated with a first coronary event is often underestimated when only those who survive to reach a hospital are considered. Few studies have examined long-term trends in case fatality associated with a major coronary event that occurs out of the hospital.
Methods and results: Record linkage documented all case subjects 35 to 84 years of age in Sweden during 1991 to 2006 with a first major coronary event (out-of-hospital coronary death or hospitalization for acute myocardial infarction). Of the 384 597 cases identified, 111 319 (28.9%) died out of the hospital, and another 36 552 (9.5%) died in the hospital or within 28 days of hospitalization. From 1991 to 2006, out-of hospital deaths as a proportion of all major coronary events declined from 30.5% to 25.6% (adjusted mean annual decrease 2.2%, 95% confidence interval 2.1% to 2.4%), however, with a larger decline in 28-day case fatality in hospitalized cases (adjusted mean annual decrease 5.8%, 95% confidence interval 5.5% to 6.0%). As a result of the faster decline in in-hospital deaths, the relative contribution of out-of-hospital deaths to overall case fatality increased, particularly among younger individuals (eg, among those 35 to 54 years of age, no more than 10.8% of all deaths occurred in hospitalized cases during 2003-2006). Although female sex (odds ratio 0.85, 95% confidence interval 0.83 to 0.87) and older age (odds ratio 0.972, 95% confidence interval 0.971 to 0.974 per year) were associated with lower risk for initial out-of-hospital death, each successive calendar year was associated with increased risk (odds ratio 1.041, 95% confidence interval 1.038 to 1.044).
Conclusions: The great majority of all fatal coronary events occur outside the hospital, and this proportion is increasing, particularly among younger individuals.