1. Department of Molecular Medicine and Surgery, Karolinska Institute and Karolinska University Hospital, Stockholm, Sweden
2. Clinical Epidemiology and Biostatistics Unit, Örebro University Hospital, Örebro, Sweden
3. Department of Surgery, Örebro University Hospital, Örebro, Sweden
4. Department of Surgery and Centre for Clinical Research, Uppsala University, Central Hospital, Västerås, Sweden
5. Department of Clinical Research and Education, Karolinska Institute and Södersjukhuset, Stockholm, Sweden