[1] UCLA, Dept Pediat, David Geffen Sch Med, 10833 Le Conte Ave, Los Angeles, CA 90095 USA
[2] UCLA, David Geffen Sch Med, Dept Pediat, Los Angeles, CA USA
[3] Duke Univ, Sch Med, Durham, NC USA
[4] Boston Univ, Dept Pediat, Chobanian & Avedisian Sch Med, Boston, MA USA
[5] UCLA, Dept Gen Internal Med, Los Angeles, CA USA
[6] Univ Michigan, Inst Social Res, Ann Arbor, MI USA
[7] Univ Calif Los Angeles, Dept Psychiat & Biobehav Sci, Los Angeles, CA USA
[8] Univ Calif Los Angeles, UCLA Fielding Sch Publ Hlth, Dept Hlth Policy & Management, Los Angeles, CA USA