1. Clinical Effectiveness Research Group, Institute of Health and Society, University of Oslo, and Department of Transplantation Medicine Oslo University Hospital, Oslo, Norway
2. Department of Internal Medicine, University of Connecticut Health Centre, Connecticut, USA
3. Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
4. Digestive Disease Center, Showa University Northern Yokohama Hospital, Yokohama, Japan