1. Department of Biomedical and Clinical Sciences, Linköping University, 58183 Linköping, Sweden
2. Department of Surgery, Vrinnevi Hospital, 60379 Norrköping, Sweden
3. Department of Medicine, Division of Clinical Epidemiology, Karolinska University Hospital, Karolinska Institutet, 17177 Stockholm, Sweden
4. Department of Surgery, Södersjukhuset, 11883 Stockholm, Sweden
5. Department of Molecular Medicine and Surgery, Karolinska Institutet, Division of Coloproctology, Center for Digestive Diseases, Karolinska University Hospital, 17177 Stockholm, Sweden
6. Department of Surgery, Ryhov County Hospital, 55305 Jönköping, Sweden
7. Department of Surgery, Linköping University Hospital, 58183 Linköping, Sweden