1. Longitudinal Studies Section (Y.M., L.F.), Clinical Research Branch, National Institute on Aging, Baltimore, Maryland 21225
2. Department of Epidemiology and Preventive Medicine (M.S.), University of Maryland School of Medicine, Baltimore, Maryland 21201
3. Tuscany Health Regional Agency (A.M.C.), 50134 Florence, Italy
4. Department of Medicine and Sciences of Aging (R.V.), Laboratory of Clinical Epidemiology, University “G. D’Annunzio” of Chieti, 66100 Chieti, Italy
5. Geriatric Unit (S.B.), Azienda Sanitaria Firenze, 50125 Florence, Italy
6. Laboratory of Epidemiology Demography and Biometry (J.M.G.), National Institute on Aging, Bethesda, Maryland 20892