1. General Surgery Unit, Monte Naranco Hospital, 33012 Oviedo, Asturias, Spain
2. Surgery I Department, School of Medicine, Complutense University of Madrid, 28040 Madrid, Spain
3. Surgery Department, La Paz Hospital, Autonomous University of Madrid, 28046 Madrid, Spain
4. Internal Medicine Department, Puerta de Hierro Hospital, Autonoma University of Madrid, Majadahonda, 28013 Madrid, Spain
5. General Surgery Unit, Virgen de la Salud Hospital, 45004 Toledo, Spain
6. Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, CA 90033, USA