1 Department of Gastro-Intestinal Surgery, Amsterdam University Medical Center, Location VU University, De Boelelaan 1117, ZH 7F020, 1081 HV, Amsterdam, The Netherlands. ni.vanderwielen@amsterdamumc.nl.
2 Department of Gastro-Intestinal Surgery, Amsterdam University Medical Center, Location VU University, De Boelelaan 1117, ZH 7F020, 1081 HV, Amsterdam, The Netherlands.
3 Department of Clinical Epidemiology, Amsterdam University Medical Center, Amsterdam, The Netherlands.
4 Department of Surgery, San Raffaele Hospital, Milan, Italy.
5 Department of Visceral-, Thoracic and Vascular Surgery, University Hospital Carl Gustav Carus, Dresden, Germany.
6 Department of Surgery, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany.
7 Department of Surgery, Hospital Universitario de Basurto, Bilbao, Spain.
8 Department of Surgery, Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain.
9 Department of Surgery, Hospital de Jerez, Jerez de la Frontera, Spain.
10 Department of Surgery, Hospital Clínico San Carlos, Madrid, Spain.
11 Department of Surgery, IRCCS Policlinico San Donato, Milan, Italy.
12 Department of Surgery, Hospital del Sureste, Madrid, Spain.
13 Department of Surgery, Karolinska University Hospital, Stockholm, Sweden.
14 Department of Gastro-intestinal Surgery, Amsterdam University Medical Center Location AMC, Amsterdam, The Netherlands.
15 Department of Surgery, ASST Spedali Civili, Brescia, Italy.
16 Department of Surgery, Salford Royal NHS Foundation Trust, Manchester, UK.