1. Center for Digestive Endoscopy, University Clinic “Dr Dragisa Misovic”, 11000 Belgrade, Serbia
2. School of Medicine, University of Belgrade, 11000 Belgrade, Serbia
3. Gastroenterology Unit, University Hospital of Udine, 33100 Udine, Italy
4. Department of Gastroenterology, Clinical Hospital Center Rijeka, 51000 Rijeka, Croatia
5. Faculty of Health Studies, 51000 Rijeka, Croatia
6. Euroimmun—Medizinische Labordiagnostika AG, 23560 Lübeck, Germany
7. Institute of Clinical Pathology, University Hospital of Udine, 33100 Udine, Italy
8. Department of Medicine, University of Udine, 33100 Udine, Italy
9. General Surgery and Transplantation Unit, University Hospital of Udine, 33100 Udine, Italy
10. Digestive Endoscopy Department, Isola Tiberina Hospital—Gemelli Isola, 00186 Rome, Italy
11. Department of Gastroenterology, Royal Cornwall Hospitals NHS Trust, Truro TR1 3LJ, UK