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.

Cancer Registry of the Somme Inserm EA DGS EA 4666 Epidemiology and Public Health Service Amiens University Hospital Amiens France

Clinique Sainte Isabelle Abbeville France

Department of Pathology Amiens University Hospital Amiens France

Gastroenterology Unit Epimad Registry Amiens University Hospital Amiens France

Gastroenterology Unit Hôpital Charles Nicolle Rouen University Hospital Epimad Registry Rouen France

ISCARE 1 5 F a s IBD Clinical and Research Center Prague Czech Republic

Lille University and Hospital Public Health Epidemiology and Economic Health Registre Epimad Maison Régionale de la Recherche Clinique Lille France Lille University Inserm LIRIC Unit UMR 995 Team 5 Faculté de Médecine Lille France

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