[1] Univ Minnesota, Dept Pediat, Div Adolescent Hlth & Med, Sch Publ Hlth, Minneapolis, MN 55455 USA
[2] Univ Minnesota, Sch Publ Hlth, Div Epidemiol & Community Hlth, Minneapolis, MN 55455 USA
[3] Columbia Univ, Dept Biostat, New York, NY USA
[4] Columbia Univ, Dept Psychiat, New York, NY USA