1. Durham Veterans Affairs Geriatric Research Education and Clinical Center, Durham Veterans Affairs Medical Center (VAMC), Durham, NC, USA
2. Department of Medicine, Duke University, Durham, NC, USA
3. Center for Study of Aging and Human Development, Duke University, Durham, NC, USA
4. Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC, USA
5. Department of Sociology, Duke University, Durham NC, USA
6. Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL, USA
7. Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
8. Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA