1. Institute of Internal Medicine, Catholic University of Rome, Largo Francesco Vito 1, 00168 Rome, Italy
2. Internal Medicine and Gastroenterology Unit, Complesso Integrato Columbus, Via Giuseppe Moscati 31-33, 00168 Rome, Italy
3. Department of Epidemiology, IRCCS-“Mario Negri” Institute for Pharmacological Research, Via G. La Masa 19, 20156 Milan, Italy
4. Department of Clinical Sciences and Community Health, University of Milan, Via G. Venezian 1, 20122 Milan, Italy
5. Institute of Public Health Section of Hygiene, Catholic University of Rome, Largo Francesco Vito 1, 00168 Rome, Italy