[1] NIA, Lab Epidemiol Demog & Biometry, Bethesda, MD 20892 USA
[2] Univ Michigan, Inst Social Res Social Environm & Hlth, Ann Arbor, MI 48109 USA
[3] NIA, Ctr Gerontol Res, Baltimore, MD 21224 USA
[4] Univ Tennessee, Dept Prevent Med, Memphis, TN USA
[5] Univ Pittsburgh, Div Geriatr Med, Pittsburgh, PA USA
[6] Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA 94143 USA