1. Department of Surgery Institute of Clinical Sciences SSORG – Scandinavian Surgical Outcomes Research Group Sahlgrenska Academy at University of Gothenburg Gothenburg Sweden
2. Region Västra Götaland Sahlgrenska University Hospital/ÖstraDepartment of SurgeryGothenburg Sweden
3. Department of Surgery Blekinge Hospital Karlshamn Sweden
4. Department of Surgery Herlev Hospital University of Copenhagen Herlev Denmark