The long-term disease course of microscopic colitis: a European prospective incident cohort study

Background and Aims The disease course of microscopic colitis is largely unknown and current knowledge is based on retrospective data. The aim of the PRO-MC Collaboration is to prospectively describe the long-term disease course and prognostic factors. Methods Incident patients of microscopic colitis were included in a prospective, European, multicenter, web-based registry. Data on patient characteristics, symptoms, treatment, and quality of life were systematically registered at baseline and during fixed follow-up intervals. Four disease course phenotypes were defined. Results Of 422 registered incident patients, 220 had a complete 5-year follow-up. After 5 years, 6% had a quiescent disease course, 54% achieved remission after treatment, 33% had a relapsing disease course, and 7% a chronic active disease course. Patients with a relapsing or chronic active disease course had a more impaired quality of life and were more often in need for long-term budesonide treatment. The disease course in the first year after diagnosis was the only predictor of the disease course. Conclusions Microscopic colitis is a chronic condition with relapsing or continuous disease course in nearly half of the patients during the first 5 years after diagnosis. The disease course in the first year predicts the long-term disease course.