[1] Johns Hopkins Univ, Dept Med, Div Nephrol, Baltimore, MD USA
[2] Johns Hopkins Univ, Dept Epidemiol, Baltimore, MD USA
[3] Cincinnati Childrens Hosp, Dept Pediat, Div Nephrol, Cincinnati, OH USA
[4] Montreal Childrens Hosp, Dept Pediat, Montreal, PQ, Canada
[5] Childrens Hosp Philadelphia, Dept Pediat, Div Nephrol, Philadelphia, PA 19104 USA
[6] Univ Penn, Ctr Clin Epidemiol & Biostat, Philadelphia, PA 19104 USA
[7] Childrens Mercy Hosp, Dept Pediat, Div Nephrol, Kansas City, MO 64108 USA