1. Endoscopy Unit, Department of Digestive Diseases, Hospital Universitari de Bellvitge, Bellvitge Biomedical Research Institute (IDIBELL), University of Barcelona, Barcelona, Catalonia, Spain
2. Endoscopy Unit, Department of Digestive Diseases, Complejo Universitario de Navarra, Pamplona, Spain
3. Endoscopy Unit, Department of Digestive Diseases, Hospital Universitario Rio Hortega, Valladolid, Spain
4. Endoscopy Unit, Department of Digestive Diseases, Hospital General Universitario de Alicante, Alicante, Spain
5. Endoscopy Unit, Department of Digestive Disease, Hospital Universitario Virgen del Rocio, Sevilla, Spain
6. Endoscopy Unit, Department of Digestive Diseases, Hospital Universitario Ramon y Cajal, Madrid, Spain
7. Health Science Department, Universitat Oberta de Catalunya, Barcelona, Catalonia, Spain