1. Department of Surgery and Department of Biomedical and Clinical Sciences Linköping University Norrköping Sweden
2. Division of Upper Abdominal Diseases, Karolinska University Hospital, and Unit of Gastroenterology, Department of Medicine (Huddinge) Karolinska Institutet Stockholm Sweden
3. Clinical Epidemiology Division, Department of Medicine (Solna) Karolinska Institutet Stockholm Sweden
4. Clinical Epidemiology Division, Department of Medicine (Solna), Karolinska Institutet, and Center for Obesity Academic Specialist Center, Stockholm Health Services Stockholm Sweden