1. Duke Clinical Research Institute, Duke University, Durham, NC
2. Department of Population Health Sciences, Duke University, Durham, NC
3. Department of Sociology, Duke University, Durham, NC
4. Population Division, United Nations, New York, NY
5. Duke School of Nursing, Duke University Medical Center, Durham, NC
6. Department of Community and Family Medicine, Duke University, Durham, NC
7. Division of Cardiology, Department of Medicine, Duke University, Durham, NC