[1] Memphis VA Med Ctr, Nephrol Sect, Memphis, TN USA
[2] Univ Calif Los Angeles, David Geffen Sch Med, Dept Med, Los Angeles, CA 90095 USA
[3] Duke Univ, Dept Med, Durham, NC USA
[4] Univ Tennessee, Div Nephrol, Hlth Sci Ctr, Memphis, TN USA
[5] Univ Virginia, Dept Med, Dept Publ Hlth Sci, Div Nephrol, Charlottesville, VA USA
[6] Univ Calif Irvine, Div Nephrol & Hypertens, Harold Simmons Ctr Chron Dis Res & Epidemiol, Orange, CA 92668 USA