1. Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands
2. Department of Gastroenterology and Hepatology, Deventer, The Netherlands
3. Department of Surgery, Amsterdam, The Netherlands
4. Department of Surgery, Gelre Hospital, Apeldoorn, The Netherlands
5. Clinical Research Unit, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
6. Department of Surgery, Deventer Hospital, Deventer, The Netherlands