1. Department of Abdominal Surgery, University Hospitals Gasthuisberg Leuven, Belgium
2. Department of Surgery, Ospedale Santa Maria degli Angeli, Pordenone, Italy
3. Interuniversity centre for Biostatistics and Statistical Bioinformatics, Leuven, Belgium
4. Department of Digestive and Endocrine Surgery, University Hospital, Hotel Dieu, Nantes, France