2Department of Gastroenterology, Oslo University Hospital, Oslo, Norway; 3Institute of Clinical Medicine, University of Oslo, Oslo, Norway Correspondence: Sandre Svatun Lirhus Department of Health Management and Health Economics, University of Oslo, Forskningsveien 3A, Harald Schjelderups Hus, Oslo, 0373, Norway Tel +47 97 58 29 25 Background: Countries have different diagnostic procedures and treatment regimens for inflammatory bowel disease (IBD) patients. In addition to differences in population characteristics, completeness of data and health registries, different follow-up time and case...