1. Department of Gastrointestinal Surgery, Akershus University Hospital, Lørenskog, Norway2Faculty of Medicine, University of Oslo, Oslo, Norway
2. Department of Gastrointestinal Surgery, Oslo University Hospital, Oslo, Norway
3. Department of Surgery, University Hospital, Linköping, Sweden
4. Department of Gastrointestinal Surgery, Østfold Hospital, Fredrikstad, Norway
5. Department of Gastrointestinal and Emergency Surgery, Haukeland University Hospital, Bergen, Norway
6. Colorectal Unit, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
7. Colorectal Unit, Department of Surgery, Helsingborg Hospital, Helsingborg, Sweden
8. Department of Gastrointestinal Surgery, Stavanger University Hospital, Stavanger, Norway
9. Health Services Research Unit, Akershus University Hospital, Lørenskog, Norway