[1] Univ Toronto, Hosp Sick Children, Dept Paediat, Div Paediat Med, Toronto, ON, Canada
[2] Univ Colorado, Sch Med, Dept Pediat, Aurora, CO USA
[3] Childrens Hosp Colorado, Special Care Clin, Aurora, CO USA
[4] SickKids Res Inst, Child Hlth Evaluat Sci, Toronto, ON, Canada
[5] Univ Toronto, Inst Hlth Policy Management & Evaluat, Toronto, ON, Canada
[6] Univ Oxford, Ctr Evidence Based Med, Oxford, England
[7] Hosp Sick Children, Toronto, ON, Canada
[8] Univ Cincinnati, Coll Med, Dept Pediat, Cincinnati, OH USA
[9] Cincinnati Childrens Hosp Med Ctr, Div Hosp Med, Cincinnati, OH 45229 USA
[10] Childrens Hosp Boston, Div Gen Pediat, Boston, MA USA
[11] Harvard Med Sch, Dept Pediat, Boston, MA 02115 USA
[12] Northwestern Univ, Dept Pediat, Feinberg Sch Med, Ann & Robert H Lurie Childrens Hosp Chicago,Div H, Chicago, IL 60611 USA
[13] La Rabida Childrens Hosp & Res Ctr, Sect Chron Dis, Chicago, IL USA
[14] Univ Toronto, Edwin SH Leong Ctr Hlth Children, Toronto, ON, Canada
[15] McMaster Univ, CanChild Ctr Childhood Disabil Res, Hamilton, ON, Canada