[1] Univ Penn, Dept Emergency Med, Philadelphia, PA 19104 USA
[2] Univ Penn, Leonard Davis Inst Hlth Econ, Philadelphia, PA 19104 USA
[3] Univ Penn, Ctr Clin Epidemiol & Biostat, Philadelphia, PA 19104 USA
[4] Cincinnati Childrens Hosp Med Ctr, Dept Hlth & Human Serv, Cincinnati, OH USA
[5] Cincinnati Childrens Hosp Med Ctr, Ctr Hlth Care Qual, Cincinnati, OH USA
[6] Cincinnati Childrens Hosp Med Ctr, Div Hlth Policy & Clin Effectiveness, Cincinnati, OH USA
[7] Cincinnati Childrens Hosp Med Ctr, Div Gen Pediat, Cincinnati, OH USA
[8] Robert Wood Johnson Fdn Clin Scholars Program, Chapel Hill, NC USA
[9] Agcy Healthcare Res & Qual, Rockville, MD USA