Incidence, Clinical Presentation, and Associated Factors of Microscopic Colitis in Northern France: A Population-Based Study.

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.

Long-Term Natural History of Microscopic Colitis: A Population-Based Cohort.

OBJECTIVES: Data on long-term natural history of microscopic colitis (MC), including collagenous (CC) and lymphocytic colitis (LC), are lacking. METHODS: All new cases of MC diagnosed in the Somme area, France, between January 1, 2005, and December 31, 2007, were prospectively included. Colonic biopsies from all patients were reviewed by a group of 4 gastrointestinal pathologist experts to assess the diagnosis of CC or LC. Demographic and clinical data were retrospectively collected from diagnosis to February 28, 2017. RESULTS: One hundred thirty cases of MC, 87 CC and 43 LC, were included (median age at diagnosis: 70 [interquartile range, 61-77] and 48 [IQR, 40-61] years, respectively). The median follow-up was 9.6 years (7.6; 10.6). By the end of the follow-up, 37 patients (28%) relapsed after a median time of 3.9 years (1.2; 5.0) since diagnosis, without significant difference between CC and LC (30% vs 26%; P = 0.47). Twenty patients (15%) were hospitalized for a disease flare, and 32 patients (25%) presented another autoimmune disease. Budesonide was the most widely used treatment (n = 74, 59%), followed by 5-aminosalicylic acid (n = 31, 25%). The median duration of budesonide treatment was 92 days (70; 168), and no adverse event to budesonide was reported. Sixteen patients (22%) developed steroid dependency and 4 (5%) were corticoresistant. No difference in the risk of digestive and extradigestive cancer was observed compared with the general population. None of the death (n = 25) observed during the follow-up were linked to MC. In multivariate analysis, age at diagnosis (HR, 1.03; 95% confidence interval, 1.00-1.06; P = 0.02) and budesonide exposure (HR, 2.50; 95% confidence interval, 1.11-5.55; P = 0.03) were significantly associated with relapse. DISCUSSION: This population-based study showed that after diagnosis, two-third of the patients with MC observed long-term clinical remission. Age at diagnosis and budesonide exposure were associated with a risk of relapse.