The Epidemiology of Microscopic Colitis in Olmsted County From 2002 to 2010: A Population-Based Study

BACKGROUND & AIMS: The increasing incidence of microscopic colitis has been partly attributed to detection bias. We aimed to ascertain recent incidence trends and the overall prevalence of microscopic colitis in a population-based study. METHODS: Using data from the Rochester Epidemiology Project, we identified residents of Olmsted County, Minnesota, who were diagnosed with collagenous colitis or lymphocytic colitis from January 1, 2002, through December 31, 2010, based on biopsy results and the presence of diarrhea (N = 182; mean age at diagnosis, 65.8 years; 76.4% women). Poisson regression analyses were performed to evaluate associations between incidence and age, sex, and calendar period. RESULTS: The age-and sex-adjusted incidence of microscopic colitis was 21.0 cases per 100,000 person-years (95% confidence interval [CI], 18.0-24.1 cases per 100,000 person-years). The incidence of lymphocytic colitis was 12.0 per 100,000 person-years (95% CI, 9.6-14.3 per 100,000 person-years) and collagenous colitis was 9.1 per 100,000 person-years (95% CI, 7.0-11.1 per 100,000 person-years). The incidence of microscopic colitis and its subtypes remained stable over the study period (P = .63). Increasing age (P < .001) and female sex (P < .001) were associated with increasing incidence. On December 31, 2010, the prevalence of microscopic colitis was 219 cases per 100,000 persons (90.4 per 100,000 persons for collagenous colitis and 128.6 per 100,000 persons for lymphocytic colitis). CONCLUSION: The incidence of microscopic colitis in Olmsted County residents has stabilized and remains associated with female sex and increasing age.