1. Department of Surgery, Faculty of Medicine and Health, Örebro University , Örebro , Sweden
2. Clinical Epidemiology and Biostatistics, School of Medical Sciences, Örebro University , Örebro , Sweden
3. Unit of Integrative Epidemiology, Institute of Environmental Medicine, Karolinska Institutet , Stockholm , Sweden
4. Department of Surgical Sciences, Uppsala University , Uppsala , Sweden
5. Division of Surgery, Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet , Stockholm , Sweden