1. Department of Gastroenterology, Oslo University Hospital, Oslo, Norway
2. Faculty of Medicine, University of Oslo, Oslo, Norway
3. Department of Rheumatology, Oslo University Hospital, Oslo, Norway
4. Department of Diagnostic Imaging, Akershus University Hospital, Oslo, Norway
5. Faculty of Public Health, Oslo and Akershus University College, Oslo, Norway
6. Sørlandet Hospital, Department of Internal Medicine, Arendal, Norway
7. Østfold Hospital Trust, Gastroenterology, Grålum, Norway