Objective: To date, there are no epidemiological data on microscopic colitis (MC) in France. The aim of this study was to determine the incidence of MC in the Somme department in Northern France, to evaluate clinical characteristics, and to search for risk factors for both collagenous colitis (CC) and lymphocytic colitis (LC).
Design: Between January 1, 2005, and December 31, 2007, four pathology units in the Somme department recorded all new cases of MC diagnosed in patients living in the area. Colonic biopsies were reviewed by 4 pathologists together. For each incident case, demographic, clinical, endoscopic, and biological data were collected according to methodology of the EPIMAD registry.
Results: One hundred and thirty cases of MC, including 87 CC and 43 LC, were recorded during the three-year study. The mean annual incidence for MC was 7.9/105 inhabitants, 5.3/105 inhabitants for CC, and 2.6/105 inhabitants for LC. Annual standardized incidence of Crohn's disease and ulcerative colitis in the EPIMAD registry during the same period (2005-2007) were 7.4/105 and 4.9/105, respectively. Median age at diagnosis was 63 years for MC, 70 for CC, and 48 for LC. The female-to-male gender ratio was 3.5 for MC, 4.1 for CC, and 2.6 for LC. Median time to diagnosis was 8 weeks. Chronic diarrhea and abdominal pain were, respectively, present in 93 and 47 % of the cases. An autoimmune disease was associated in 28 % of MC cases. At diagnosis, proton pump inhibitor treatment was more often reported in CC than in LC (46 vs 16 %; p = 0.003). Budesonide was effective on diarrhea in 77 % of patients, and thirteen percent of patients became steroid dependent.
Conclusion: This population-based study shows that the incidence of MC in France is high and similar to Crohn's disease incidence and confirms that this condition is associated with female gender, autoimmune diseases, and medications.
Keywords: Collagenous colitis; Incidence; Lymphocytic colitis; Microscopic colitis; Population based.