1. Department of Internal Medicine, Haraldsplass Diaconal Hospital, 5009 Bergen, Norway
2. Department of Gastroenterology, Haukeland University Hospital, 5009 Bergen, Norway
3. Department of Gastroenterology, Landspitali University Hospital, 101 Reykjavik, Iceland
4. Faculty of Medicine, University of Iceland, 101 Reykjavik, Iceland