1. Praxis für Gastroenterologie, Berlin, Germany
2. Department of Gastroenterology, Vivantes Klinikum im Friedrichshain, Berlin, Germany
3. Department of General Surgery, Vivantes Klinikum im Friedrichshain, Berlin, Germany
4. Department of Urology, Ruhr University of Bochum Faculty of Medicine, Bochum, Germany
5. Department of Gastroenterology, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
6. Department of internal medicine, Ulm University Medical Faculty, Ulm, Germany