1. a Duke Palliative Care Service , Duke University Medical Center , Durham , North Carolina , USA
2. b Duke University School of Medicine , Durham , North Carolina , USA
3. c Department of Human Environmental Studies , Central Michigan University , Mt. Pleasant , Michigan , USA
4. d Department of Medicine and the Center for the Study of Aging , Duke University Medical Center , Durham , North Carolina , USA
5. e Geriatric Research, Education and Clinical Center , Durham VA Medical Center , Durham , North Carolina , USA