1. Gastroenterology Unit, Policlinico Universitario Tor Vergata, 00133 Rome, Italy
2. Department of Systems Medicine, University of Rome Tor Vergata, Via Montpellier, 00133 Rome, Italy
3. Facility of Epidemiology and Biostatistics, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, 00168 Rome, Italy