1. Endoscopy Unit, Department of Digestive Diseases, Hospital Universitari de Bellvitge, Bellvitge Biomedical Research Institute (IDIBELL), University of Barcelona, Catalonia, Spain
2. Endoscopy Unit, Department of Digestive Diseases, Hospital Universitario Ramon y Cajal, Madrid
3. Faculty of Health Sciences, Universitat Oberta de Catalunya, Barcelona, Catalonia, Spain