[1] Univ Padua, Dept Womens & Childrens Hlth, Div Pediat Infect Dis, I-35128 Padua, Italy
[2] Univ Milano Bicocca, Dept Stat & Quantitat Methods, Unit Biostat Epidemiol & Publ Hlth, Lab Healthcare Res & Pharmacoepidemiol, I-20126 Milan, Italy
[3] IRCCS Azienda Osped Univ Bologna, Pediat Emergency Unit, I-40138 Bologna, Italy
[4] Univ Padua, Pediat Emergency Dept, Dept Womens & Childrens Hlth, I-35128 Padua, Italy
[5] Fdn Policlin Univ A Gemelli IRCCS, Dept Anesthesia & Intens Care, I-00168 Rome, Italy