[1] Northwestern Univ, Ann & Robert H Lurie Childrens Hosp Chicago, Feinberg Sch Med, Dept Pediat,Div Emergency Med, Chicago, IL USA
[2] Northwestern Univ, Ann & Robert H Lurie Childrens Hosp Chicago, Feinberg Sch Med, Smith Child Hlth Outcomes Res & Evaluat Ctr, Chicago, IL USA
[3] Univ Cincinnati, Cincinnati Childrens Hosp Med Ctr, Dept Pediat, Div Gen & Community Pediat, Cincinnati, OH USA
[4] Univ Cincinnati, Cincinnati Childrens Hosp Med Ctr, Dept Pediat, Div Hosp Med, Cincinnati, OH USA
[5] Ann & Robert H Lurie Childrens Hosp Chicago, Div Emergency Med, 225 E Chicago Ave, Chicago, IL 60611 USA