P645. Epidemiology of microscopic colitis – a 10-year nationwide Danish cohort study
T. Wigh1, M. Fenger Grøn2, G. Lauge Nielsen3, O. Bonderup4, 1Regionalhospital Randers, Medical Department, Randers, Denmark, 2Aarhus University & Aarhus University Hospital., Research Unit for General Practice and Department of Clinical Epidemiology, Aarhus, Denmark, 3Himmerland Hospital, Medical Department, Farsø, Denmark, 4Silkeborg Hospital, Section of Gastroenterology, Silkeborg, Denmark
Microscopic colitis includes: collagenous colitis (CC) and lymphocytic colitis (LC). European and North American studies have investigated the epidemiology of microscopic colitis and found an increasing incidence from 1990–2000. A study from US indicated a combined annual incidence of microscopic colitis of 19.7/100.000. Previous studies are mainly based on regional registries and we found it of interest to study the epidemiology based on a comprehensive nationwide data.
The aim of the study was to estimate the development in the incidence and demography of microscopic colitis in Denmark from 2002–2011 based on Danish national registries.
This registry study was based on the datasets covering the entire Danish population of around 5.4 mio. inhabitants. The cohort consisted of all patients with a first time recorded diagnosis of either CC or LC in the Danish Pathology Register from January 2002 to December 2011. This register was established in 1990 and in 1997 it became a legal obligation for all departments of pathology in Denmark to report all pathology data statements and the diagnoses were coded according to a Danish version of the Systematized Nomenclature of Medicine (SNOMED). The data is used by the pathologists in the daily diagnostic process and covers all pathology data in Denmark.
The cohort consisted of a total of 7.777 patients, hereof 4.749 (61%) with CC and 3.028 (39%) with LC. In the 10-year period the annual incidence of diagnosed cases of CC increased from 2.9/100.000 to 14.9/100.000 and of LC from 1.7/100.000 to 9.8/100.000. The female:male ratio was 3:1 for CC and 1.8:1for LC. The mean age at diagnosis was 67 years for CC and 64 years for LC. There was no change in the distribution between CC and LC, the female:male ratio or the age of diagnosis during the 10-year period. The annual number of persons with registered colon-biopsies in the pathology register increased from 21.583 in 2002 to 39.733 in 2011 indicating an increased diagnostic activity.
In a nationwide cohort study the incidence of CC and LC was increasing in a ten-year period from 2002 to 2011. In 2011 a combined incidence of microscopic colitis of 24.7/100.000 was found. There was no change in the distribution of type, gender or age at diagnosis in the period. An increased diagnostic activity seems to explain the increase of diagnosed cases.