[1] Univ Padua, Dept Cardiothoracovasc Sci & Publ Hlth, Padua, Italy
[2] Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden
[3] Orebro Univ, Orebro Univ Hosp, Dept Pediat, Orebro, Sweden
[4] Univ Nottingham, Sch Med, Div Epidemiol & Publ Hlth, Nottingham, England
[5] Columbia Univ Coll Phys & Surg, Dept Med, New York, NY USA
[6] Hlth Directorate, Epidemiol Serv, Udine, Italy
[7] Univ Hosp Padua, Dept Surg Oncol & Gastroenterol, Gastroenterol Sect, Padua, Italy
[8] Dept Cardiac Thorac & Vasc Sci & Publ Hlth, Via Loredan 18, I-35131 Padua, Italy