[1] La Princesa Univ Hosp, IP, Madrid, Spain
[2] La Princesa Univ Hosp, CIBEREHD, Madrid, Spain
[3] Hop Pellegrin, F-33076 Bordeaux, France
[4] Dipartimento Med Interna & Specialita Med, Genoa, Italy
[5] Univ Piemonte Orientale, Paediat Endoscopy Units, Novara, Italy
[6] McGill Univ, Ctr Hlth, Montreal, PQ, Canada
[7] Univ N Texas, Dept Epidemiol, Hlth Sci Ctr, Ft Worth, TX USA
[8] Dipartimento Med Interna & Gastroenterol, Bologna, Italy