[1] Univ Penn, Perelman Sch Med, Dept Pediat, Philadelphia, PA 19104 USA
[2] Univ Penn, Perelman Sch Med, Dept Anesthesia & Crit Care, Philadelphia, PA 19104 USA
[3] Univ Penn, Perelman Sch Med, Ctr Clin Epidemiol & Biostat, Philadelphia, PA 19104 USA
[4] Univ Penn, Perelman Sch Med, Dept Med, Div Infect Dis, Philadelphia, PA 19104 USA
[5] Childrens Hosp Philadelphia, Div Emergency Med, Philadelphia, PA 19104 USA
[6] Childrens Hosp Philadelphia, Ctr Pediat Clin Effectiveness, Philadelphia, PA 19104 USA
[7] Childrens Hosp Philadelphia, Ctr Biomed Informat, Philadelphia, PA 19104 USA
[8] Childrens Hosp Philadelphia, Div Crit Care, Philadelphia, PA 19104 USA
[9] Northwestern Univ, Dept Pediat, Feinberg Sch Med, Chicago, IL 60611 USA
[10] Ann & Robert H Lurie Childrens Hosp Chicago, Div Emergency Med, Chicago, IL 60611 USA