1. Carolina Muszynska Department of Surgery Skåne University Hospital Department of Clinical Sciences Lund University Lund SE-221 85 Sweden
2. Department of Surgery, County Council of Östergötland, Linköping University, Linköping, Sweden
3. Department of Biomedicine and Clinical Sciences, Faculty of Health Sciences, Linköping University, Linköping, Sweden
4. Unit for Medical Statistics and Epidemiology, Clinical Studies Sweden—Forum South, Skåne University Hospital, Lund, Sweden
5. Department of Surgery, Skåne University Hospital and Department of Clinical Sciences, Lund University, Lund, Sweden