1. Department of Surgery Erasmus University Medical Center Rotterdam The Netherlands
2. Department of Surgery University Hospital Antwerp Edegem Belgium
3. Department of Biostatistics Erasmus University Medical Center Rotterdam The Netherlands
4. Department of Surgery Isala Zwolle The Netherlands
5. Department of Surgery IJsselland Ziekenhuis Capelle aan den IJssel The Netherlands
6. Department of Surgery Reinier de Graaf Gasthuis Delft The Netherlands
7. Department of Surgery VU University Medical Center Amsterdam The Netherlands
8. Department of Surgery Jeroen Bosch Ziekenhuis Hertogenbosch The Netherlands
9. Department of Surgery Universitair Medisch Centrum Utrecht Utrecht The Netherlands
10. Department of Surgery Onze Lieve Vrouwe Gasthuis Amsterdam The Netherlands
11. Departmenf of Abdominal Surgery University Hospital Leuven Leuven Belgium