[1] Morehouse Sch Med, Dept Med, Atlanta, GA 30310 USA
[2] Univ Pittsburgh, Sch Med, Pittsburgh, PA USA
[3] Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA 94143 USA
[4] Calif Pacific Med Ctr, Res Inst, San Francisco, CA USA
[5] Univ Florida, Coll Med, Dept Aging & Geriatr Res, Gainesville, FL USA
[6] Univ Tennessee, Dept Prevent Med, Memphis, TN USA
[7] NIA, Lab Epidemiol Demog & Biometry, Bethesda, MD 20892 USA