1. Department of surgery, Regional Council of Gävleborg, Gävle
2. Department of Surgery, SSORG - Scandinavian Surgical Outcomes Research Group, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg
3. Department of Statistics, Umeå School of Business, Economics and Statistics, Umeå University
4. Department of Molecular Meidicine and Surgery, Karolinska Institute, and Ersta Hospital, Stockholm
5. Department of Surgery, Faculty of Medicine and Health, Örebro University, Örebro
6. Department of Surgery, Skåne University Hospital, Malmö, Lund University, Lund
7. Department of Surgical and Perioperative Sciences, Surgery, Umeå University, Umeå