1. Department of Family Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC.
2. Program on Integrative Medicine, Department of Physical Medicine and Rehabilitation, University of North Carolina at Chapel Hill, Chapel Hill, NC.
3. Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC.
4. Department of Community and Family Medicine, Duke University, Durham, NC.
5. Department of Statistics, North Carolina State University, Raleigh, NC.