1. HUNT Research Centre, Department of Public Health and Nursing, NTNU, Norwegian University of Science and Technology, Levanger, Norway
2. Department of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA
3. Medical Department, Levanger Hospital, Nord-Trøndelag Hospital Trust, Levanger, Norway
4. Upper Gastrointestinal Surgery, Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden