1. 3rd Academic Department of Internal Medicine, GI Unit, University of Athens, Sotiria Hospital
2. Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens
3. Gastroenterology Department, Alexandra General Hospital, Athens, Greece
4. GI Department General Hospital Nikaias-Piraeus Agios Panteleimon- General Hospital Dytikis Attikis Agia Varvara