1. Department of Public Health and AFINES Program, School of Medicine, U.N.A.M. Pacific Operating Center, México City, México;
2. Division of Geriatric Medicine, St. Louis University and GRECC, St. Louis VAMC, St. Louis, Missouri; and
3. Coordinación of Internal Medicine, Hospital Dr. Darío Fernánde I.S.S.S.T.E., México City, México.