Incidence of fatal myocarditis: a population-based study in Finland

Abstract

To study the incidence of fatal myocarditis in the general population, the authors retrospectively collected all death certificates recording myocarditis as the underlying cause of death in Finland in 1970-1998. The incidence of myocarditis and its proportion of all deaths were calculated from 141.4 million person-years and 1.35 million deaths. Myocarditis was recorded as the underlying cause of death in 639 cases. Thus, its death certificate-based incidence was 0.46 (95% confidence interval (CI): 0.43, 0.49) per 100,000 person-years, and it caused 0.47 (95% CI: 0.44, 0.51) of 1,000 deaths. The incidence of 0.51 (95% CI: 0.46, 0.56) in males was higher than the incidence of 0.42 (95% CI: 0.37, 0.47) in females, the odds ratio being 1.34 (95% CI: 1.15, 1.58) (p < 0.001). The proportion of deaths caused by myocarditis was highest (up to six of 1,000 deaths) in children and adults aged less than 45 years. Because previous histopathologic reanalysis showed that only 32% of cases fulfilled the Dallas criteria, the authors estimated the incidence of histopathologically certain fatal myocarditis to be 0.15 (95% CI: 0.13, 0.17) per 100,000. The death certificate-based incidence of fatal myocarditis was found to be 0.46 per 100,000, and the histopathologically corrected incidence was 0.15 per 100,000.