Trends in out-of-hospital deaths due to coronary heart disease in Sweden (1991 to 2006).

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.