1. Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet , Stockholm , Sweden
2. Department of Surgery, Mora Hospital , Mora , Sweden
3. Center for Clinical Research, Uppsala University , Falun , Sweden
4. Department of Clinical Science and Education, South General Hospital, Karolinska Institutet , Stockholm , Sweden
5. Department of Surgical and Perioperative Sciences, Surgery, Umeå University , Umeå , Sweden
6. Department of Surgery, Sunderby Hospital , Luleå , Sweden