1. Clinic for Visceral and Thoracic Surgery, Cantonal Hospital of Winterthur, Winterthur, Switzerland
2. Department of Paediatric Surgery, Children’s University Hospital, Basle, Switzerland
3. Visceral Surgery, Hirslanden Klinik St Anna, Lucerne, Switzerland
4. Department of Transplant Surgery, University of Colorado Hospital, Aurora, Colorado, USA
5. Gastrointestinal Surgery, Royal North Shore Hospital, St Leonards, New South Wales, Australia
6. Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland