1. Department of Surgery, Hospital Universitari de Bellvitge, L'Hospitalet del Llobregat, Barcelona, Spain
2. Clinical Research Support Unit, Clinical Pharmacology Department, Bellvitge University Hospital/Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
3. Department of Surgery, Complejo Hospitalario de Navarra, Pamplona, Spain
4. Department of Surgery, Donostia University Hospital, San Sebastian, Spain
5. Department of Surgery, Parc Taulí Health Corporation, Sabadell Hospital, Sabadell, Spain
6. Department of Surgery, Arnau de Vilanova University Hospital, Lleida, Spain
7. Department of Surgery, Hospital del Mar University Hospital, Barcelona, Spain
8. Department of Surgery, Basurto University Hospital, Bilbao, Spain
9. Department of Surgery, Granollers General Hospital, Granollers, Spain
10. Department of Surgery, Cruces University Hospital, Bilbao, Spain
11. Department of Surgery, Althaia Foundation, Manresa, Spain
12. Department of Surgery, Terrassa Health Consortium, Terrassa Hospital, Terrassa, Spain
13. General Surgery Department, Vall d’Hebrón University Hospital, Barcelona, Spain
14. Hepatobiliopancreatic Surgery and Transplantation Department, Vall d’Hebrón University Hospital, Barcelona, Spain
15. Department of Surgery, Viladecans Hospital, Viladecans, Spain
16. Department of Surgery, Mataró Hospital, Maresme Health Consortium, Mataró, Spain
17. Department of Surgery, Germans Trias i Pujol University Hospital, Badalona, Spain
18. Department of Surgery, Sant Joan de Deu Hospital Foundation, Martorell, Spain
19. Department of Surgery, Dr José Molina Orosa Hospital, Lanzarote, Spain
20. Department of Surgery, Joan XXIII University Hospital, Tarragona, Spain
21. Department of Surgery, Igualada University Hospital, Anoia Health Consortium, Igualada, Spain
22. Department of Surgery, Sant Pau University Hospital, Barcelona, Spain
23. Department of Surgery, Moisès Broggi Hospital, Sant Joan Despí, Spain
24. Department of Surgery, Mútua de Terrassa University Hospital, Terrassa, Spain
25. Department of Surgery, Girona Dr Josep Trueta University Hospital, Girona, Spain
26. Department of Surgery, Alto Deba Hospital, Mondragon, San Sebastián, Spain
27. Department of Surgery, Araba University Hospital, Txagorritxu Hospital, Vitoria, Spain
28. Statistical Unit, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain