1. Department of Gastrointestinal and Pediatric Surgery, Oslo University Hospital, Oslo, Norway
2. Center for Morbid Obesity, Department of Endocrinology, Morbid Obesity and Preventive Medicine, Oslo University Hospital, Oslo, Norway
3. Institute of Clinical Medicine, University of Oslo, Oslo, Norway
4. Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
5. Department of Surgery, Vrinnevi Hospital, Norrköping, Sweden
6. Department of Endocrinology, Morbid Obesity and Preventive Medicine, Oslo University Hospital, Oslo, Norway
7. Oslo Centre for Biostatistics & Epidemiology, University of Oslo, Oslo, Norway
8. Institute of Health and Care Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
9. Department of Surgery, Sahlgrenska University Hospital, Region Vastra Gotaland, Gothenburg, Sweden