1. School of Medical Sciences, Orebro University, Orebro, Sweden
2. Division of Traumatology, Surgical Critical Care and Emergency Surgery, University of Pennsylvania, Penn Presbyterian Medical Center, Philadelphia, Pennsylvania, USA
3. Division of Trauma and Emergency Surgery, Department of Surgery, Orebro University Hospital, Orebro, Sweden
4. Division of Surgery, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
5. Division of Trauma and Emergency Surgery, Department of Surgery, Karolinska University Hospital, Stockholm, Sweden
6. Department of Clinical Epidemiology and Biostatistics, School of Medical Sciences, Orebro University, Orebro, Sweden