1. Unit of Population Epidemiology, Division of Primary Care Medicine, Department of Community Medicine, Primary Care, and Emergency Medicine, Geneva University Hospitals, 4 Rue Gabrielle-Perret-Gentil, 1211 Geneva 14, Switzerland
2. Community Prevention Unit, University Institute of Social and Preventive Medicine, 10 Route de la Corniche, 1010 Lausanne, Switzerland
3. Department of Epidemiology, Rollins School of Public Health, Emory University, 1518 Clifton Road, Atlanta, GA 30322, USA
4. Birmingham/Atlanta Geriatric Research Education and Clinical Center, Atlanta Veterans Affairs Medical Center, 1670 Clairmont Road, Atlanta, GA 30322, USA
5. Department of Medicine, Emory University, 1518 Clifton Road, Atlanta, GA 30322, USA