[1] Univ Pittsburgh, Grad Sch Publ Hlth, Dept Epidemiol, Pittsburgh, PA 15261 USA
[2] Univ Michigan, Sch Med, Div Geriatr Med, Vet Affairs Ann Arbor Healthcare Syst Geriatr, Ann Arbor, MI USA
[3] Stanford Univ, Med Ctr, Dept Pathol, Stanford, CA 94305 USA
[4] Univ Vermont, Dept Pathol, Burlington, VT 05405 USA
[5] Wake Forest Univ, Sch Med, Sect Gerontol & Geriatr Med, Winston Salem, NC 27109 USA
[6] NIA, Gerontol Res Ctr, NIH, Baltimore, MD 21224 USA