1. Outpatients' Clinic of Gastroenterology University Teaching Hospital Lueneburg Lueneburg Germany
2. Gastroenterology Unit – Department of Biomedical and Clinical Science ‐ ‘L.Sacco’ University Hospital University of Milan Milan Italy
3. Department of Gastroenterology University Teaching Hospital Lueneburg Lueneburg Germany
4. Gastroenterology and Endoscopy IRCCS Ospedale San Raffaele and University Vita‐Salute San Raffaele Milan Italy