[1] Hosp Sick Children, Dept Pediat, 555 Univ Ave, Toronto, ON M5G 1X8, Canada
[2] Univ Toronto, Inst Hlth Policy Management & Evaluat, Toronto, ON, Canada
[3] Harvard Univ, Boston Childrens Hosp, Div Gen Pediat, Complex Care Serv, Boston, MA 02115 USA
[4] Harvard Univ, Harvard Med Sch, Boston, MA 02115 USA
[5] Stanford Univ, CPOP, Stanford, CA 94305 USA
[6] Stanford Univ, Dept Pediat, Sch Med, Stanford, CA 94305 USA
[7] Lucile Packard Fdn Childrens Hlth, Palo Alto, CA USA