[1] Harvard Univ, Harvard PhD Program Hlth Policy, Cambridge, MA 02138 USA
[2] Boston Childrens Hosp, Dept Med, Div Gen Pediat, Boston, MA USA
[3] Boston Childrens Hosp, Dept Med, Div Emergency Med, Boston, MA USA
[4] Harvard Univ, Sch Med, Dept Pediat, Boston, MA 02115 USA
[5] Harvard Univ, Sch Med, Dept Hlth Care Policy, Boston, MA 02115 USA
[6] Brigham & Womens Hosp, Dept Med, Div Gen Internal Med & Primary Care, Boston, MA 02115 USA