1. Division of Surgery Sunderby Hospital Luleå 97180 Sweden Sunderby Research Unit Department of Surgical and Perioperative Sciences Medical Faculty Umeå University Umeå Sweden
2. Department of Surgical and Perioperative Sciences, Medical Faculty, Umeå University, Umeå, Sweden
3. Department of Business Administration and Industrial Engineering, Luleå University of Technology, Luleå, Sweden
4. Sunderby Research Unit, Department of Surgical and Perioperative Sciences, Medical Faculty, Umeå University, Umeå, Sweden