Jens Pallenschat, Ole Høie, Bjørn Christian Elias Grova Olsen, Tahir Riaz Ahmad, Petr Ricanek, Emma Elisabeth Løvlund, Arnt Sagosen, Øistein Hovde, Florin B. Vikskjold, Stein Dahler, Stephan Brackmann, Batool Aballi, Jon Berggren Rove, Erik Skogestad, Carl Magnus Ystrøm, Gøri Perminow, Roald Torp, Aina Pedersen, Randi Opheim, Tone Bergene Aabrekk, Marte Lie Høivik, Tor Tønnessen, May-Bente Bengtson, Christine Olbjørn, Raziye Boyar Cetinkaya, Svein Oskar Frigstad, Magne Henriksen, Simen Vatn, Svend Andersen, Asle W. Medhus, Vendel Ailin Kristensen, Gert Huppertz-Hauss, Katharina Schmidt, Charlotte K. Munthe Lund, Trond Espen Detlie, Hans Kristian Holm, Ingunn Johansen, Audun Hasund, and Hussain Ali Ghalib Yassin
Background and aim: Modern treatment strategies for inflammatory bowel disease (IBD) are postulated to change the natural disease course. Inception cohort studies are the gold standard for investigating such changes. We have initiated a new population-based inception cohort study; Inflammatory bowel disease in South Eastern Norway III (IBSEN III). In this article, we describe the study protocol and baseline characteristics of the cohort. Methods: IBSEN III is an ongoing, population-based observational inception cohort study with prospective follow-up. Adult and pediatric patients with suspected IBD in the South-Eastern Health Region of Norway (catchment area of 2.95 million inhabitants in 2017), during the 3-year period from 2017 to 2019, were eligible for inclusion. Comprehensive clinical, biochemical, endoscopic, demographic, and patient-reported data were collected at the time of diagnosis and throughout standardized follow-up. For a portion of the patients, extensive biological material was biobanked. Results: The study included 2168 patients, of whom 1779 were diagnosed with IBD (Crohn's disease: 626, ulcerative colitis: 1082, IBD unclassified: 71). In 124 patients, there were subtle findings indicative of, but not diagnostic for, IBD. The remaining 265 patients were classified as symptomatic non-IBD controls. Conclusion: We have included patients in a comprehensive population-based IBD cohort from a catchment population of 2.95 million, and a unique biobank with materials from newly diagnosed and treatment-naïve IBD patients and symptomatic non-IBD controls. We believe this cohort will add important knowledge about IBD in the years to come.