1. Department of Medicine, Duke University Medical Center, Durham, North Carolina
2. Geriatric Research, Education, and Clinical Center, Durham VA Medical Center, Durham, North Carolina
3. Center for the Study of Aging, Duke University Medical Center, Durham, North Carolina
4. Durham VA Health Care System, Durham, North Carolina
5. Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina
6. Department of Surgery, Duke University Medical Center, Durham, North Carolina