Case-fatality rates for myocardial infarction declined in Denmark and Sweden during 1987-1999

To evaluate trends in prognosis after acute myocardial infarction (AMI) between Denmark and Sweden using routinely collected data and different case-fatality measures.

We compared three case-fatality measures during 1987-1999 using national registries in Denmark and Sweden, and extended these measures with underlying deaths of ischemic heart disease and sudden deaths of unknown cause.

Changed coding practice distorted trends of case fatality rates during the day of the event. In general, Denmark had higher case-fatality rates, but trends in hospital-based rates were very similar, except for men 35-64 years old; Denmark declined more steeply. Short- and long-term prognosis improved considerably: the odds ratios for case fatality during days 1-28 for 1999 vs. 1987 were 0.48 among men in Denmark (women 0.58) and 0.53 among men in Sweden (women 0.55) and the odds ratios for case fatality during days 29-365 for 1999 vs. 1987 were 0.56 among men in Denmark (women 0.65) and 0.66 among men in Sweden (women 0.67).

Short- and long-term prognosis improved considerably during 1987-1999 in Denmark and Sweden. Case fatality during the day of the event is epidemiologically important, but less certain than case-fatality measures defined after the day of the event when comparing countries.