1. Department of Surgical and Perioperative Sciences, SurgeryUmeå UniversitySE-901 85 UmeåSwedenWallenberg Centre for Molecular MedicineUmeå UniversityUmeåSweden
2. Department of Statistics, Umeå School of Business, Economics and Statistics, Umeå University, Umeå, Sweden
3. Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, SwedenDepartment of Surgery, Ersta Hospital, Stockholm, Sweden
4. Department of Surgery, Faculty of Medicine and Health, Örebro University, Örebro, Sweden
5. Department of Surgery, Skåne University Hospital and Lund University, Lund, Sweden
6. Department of Surgery, Scandinavian Surgical Outcomes Research Group (SSORG), Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden