1. Gastroenterology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy
2. Department of Medical and Surgical Sciences, University of Bologna, 40138 Bologna, Italy
3. Digestive Disease and Surgery Institute Cleveland Clinic, London SW1X 7HY, UK
4. Division of Surgery and Interventional Science, University College London, London NW1 2BU, UK
5. Department of Gastroenterology, University College London Hospital (UCLH), London NW1 2BU, UK
6. Centre for Obesity Research, Department of Medicine, Rayne Institute, University College London, London NW1 2BU, UK
7. Esophagus and Stomach Organic Diseases Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy