[1] Brown Univ, Hasbro Childrens Hosp, Rhode Isl Hosp, Warren Alpert Med Sch,Dept Emergency Med, Providence, RI 02903 USA
[2] Brown Univ, Hasbro Childrens Hosp, Rhode Isl Hosp, Warren Alpert Med Sch,Dept Pediat, Providence, RI 02903 USA
[3] Brown Univ, Sch Publ Hlth, Providence, RI 02912 USA
[4] Brown Univ, Sch Publ Hlth, Dept Epidemiol, Providence, RI 02912 USA
[5] Hassenfeld Child Hlth Innovat Inst, Providence, RI USA
[6] Brown Univ, Dept Hlth Serv Policy & Practice, Providence, RI 02912 USA