[1] Univ Calif Los Angeles, David Geffen Sch Med, Dept Pediat, Mattel Childrens Hosp, Los Angeles, CA 90095 USA
[2] RAND Corp, Santa Monica, CA USA
[3] Ctr Dis Control & Prevent Res, Div Adult & Community Hlth, Atlanta, GA USA
[4] Univ Alabama Birmingham, Dept Psychol, Birmingham, AL 35294 USA
[5] Univ Alabama Birmingham, Dept Maternal & Child Hlth, Birmingham, AL 35294 USA
[6] Univ Texas Hlth Sci Ctr Houston, Ctr Hlth Promot & Prevent Res, Houston, TX USA
[7] Harvard Univ, Sch Med, Dept Med, Childrens Hosp Boston, Boston, MA USA