[1] Cincinnati Childrens Hosp Med Ctr, Div Adolescent Med, Dept Pediat, Cincinnati, OH 45229 USA
[2] Univ Cincinnati, Coll Med, Cincinnati, OH USA
[3] Univ Alabama Birmingham, Dept Epidemiol, Birmingham, AL USA
[4] NYU, Dept Pediat, Sch Med, New York, NY 10016 USA
[5] Cincinnati Childrens Hosp Med Ctr, Dept Pediat, Div Biostat & Epidemiol, Cincinnati, OH 45229 USA