[1] Univ Pittsburgh, Childrens Hosp Pittsburgh, Sch Med, Div Pediat Endocrinol Metab & Diabet Mellitus, Pittsburgh, PA USA
[2] Univ Pittsburgh, Grad Sch Publ Hlth, Dept Epidemiol, Pittsburgh, PA USA
[3] Univ Pittsburgh, Sch Med, Dept Family Med & Clin Epidemiol, Div Biostat, Pittsburgh, PA USA