Clinical course of microscopic colitis in a single-center cohort study.

Background And Aims: The long-term natural history of collagenous (CC) and lymphocytic colitis (LC) is not well known. The aims of this study were to evaluate the clinical course of microscopic colitis (MC) and to describe the morbidity evolution of the disease.

Material And Methods: This study is based on a cohort of 54 patients (35 LC/19 CC), previously included in a randomized trial treated with mesalazine with or without cholestyramine. Patients were followed-up closely during the subsequent 5 years, undergoing clinical, endoscopic and histologic evaluation at least yearly. After this period, they were encouraged to undergo periodical clinical evaluations.

Results: In a mean follow-up time of 104.9 ± 14.1 months (range 81-138 months) at the end of the therapy, 12 patients (7 LC and 5 CC) relapsed. Of these patients, 4 reported a mild clinical relapse self-treated with antidiarrheal medication. In total 49 patients are clinically free from diarrhea, to date. At multivariate analysis the only predictive factor of relapse seems to be a slow response to treatment.

Conclusions: Only a minority of patients with MC had diarrhea more than once a week in a long-term follow-up and the symptom pattern was similar between CC and LC patients.