Objectives: A systematic review and meta-analysis was conducted to provide an accurate estimate of the incidence rate of microscopic colitis (MC) and to assess the association between medication use and the risk of MC.
Methods: We searched Medline, Embase, and Institute for Scientific Information (ISI) Web of Science up to 26 September 2014 to identify published epidemiological studies of MC. The pooled incidence rate, female-to-male incidence rate ratio, age at diagnosis, prevalence, as well as odds ratios (ORs) of MC in association with medication use were calculated using a fixed-effects model or a random-effects model.
Results: Of the 1,972 citations retrieved, 25 studies were included. Pooled incidence rate of collagenous colitis (CC) was 4.14 (95% confidence interval (CI) 2.89-5.40) per 100,000 person-years and 4.85 (95% CI, 3.45-6.25) for lymphocytic colitis (LC). The female-to-male incidence rate ratios were 3.05 (95% CI 2.92-3.19) for CC and 1.92 (95% CI 1.53-2.31) for LC. The median age at diagnosis for CC was 64.9 (range, 57.03-72.78) years, similar to LC (median 62.18, range 53.99-70.38). Furthermore, the incidence rate of MC increased with rising age. A steadily increasing trend of incidence rate for both CC and LC was observed before 2000; however, the incidence rate since then has become stable in the United States, Sweden, and Spain. An increased risk of MC was associated with the use of proton pump inhibitors (PPIs) and selective serotonin reuptake inhibitors (SSRIs) (OR 2.68, 95% CI 1.73-4.17 and OR 2.41, 95% CI 1.64-3.53, respectively).
Conclusions: MC is a common disease process. Female gender, increased age, and the use of PPIs and SSRIs are associated with a significantly increased risk of developing MC. Further work is needed to evaluate reported data from developing countries and to elucidate the biologic mechanisms behind the risk factors for MC.