[1] Stanford Univ, Sch Med, Dept Med, Div Nephrol, Palo Alto, CA 94304 USA
[2] Univ Calif San Francisco, Dept Vet Affairs Med Ctr, Nephrol Sect, San Francisco, CA 94143 USA
[3] Univ Calif San Francisco, Dept Med, Div Nephrol, San Francisco, CA USA
[4] Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA 94143 USA
[5] Dept Vet Affairs Med Ctr, Nephrol Sect, Mather, CA USA
[6] Univ Calif Davis, Dept Med, Div Nephrol, Davis, CA 95616 USA
[7] Emory Univ, Dept Rehabil Med, Atlanta, GA 30322 USA