Myocarditis and inflammatory bowel disease - A 16-year Danish nationwide cohort study

Objective: Case reports have described myocarditis in association with inflammatory bowel disease both as an extraintestinal manifestation and as a side effect of the drug treatment. We analysed the occurrence of myocarditis in patients with inflammatory bowel disease in Denmark. Design: Registry-based follow-up study from 1977 to 1992. Subjects: The study was based on the Danish nationwide hospital discharge registry, the Danish National Registry of Patients. The registry has included 15,572 patients since 1977. Additional information was obtained from the Danish Committee on Adverse Drug Reactions. Main outcome variables: Myocarditis. Results: Six cases of myocarditis were identified giving a risk of myocarditis of 4.6 per 100,000 years of risk. Compared with the background population the incidence rate ratio was 8.3 for Crohn's disease and 2.6 for ulcerative colitis. Conclusions: Patients with inflammatory bowel disease have an increased risk of myocarditis compared with the background population, but its incidence is low.