1. Department of Family Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC.
2. RTI International, Research Triangle Park, NC.
3. Department for Evidence-based Medicine and Clinical Epidemiology, Danube University, Krems, Austria.
4. Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC.
5. Cecil G. Sheps Center for Health Services Research, University of North Carolina at Chapel Hill, Chapel Hill, NC.
6. Department of Physical Medicine and Rehabilitation, University of North Carolina at Chapel Hill, Chapel Hill, NC.