作者单位:Univ Calif San Francisco, Div Nephrol, San Francisco, CA 94143 USA[1]Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA USA[2]Childrens Mercy Kansas City, Dept Pediat, Div Nephrol, Kansas City, MO USA[3]Hennepin Healthcare Med Ctr, Dept Med, Div Nephrol, Minneapolis, MN USA[4]