1. Thurston Arthritis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
2. Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
3. Injury Prevention Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
4. Health Services Research & Development, VA Medical Center, Durham, North Carolina
5. Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
6. Arthritis Program, Centers for Disease Control and Prevention, Atlanta, Georgia
7. Departments of Social Medicine and Orthopaedics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina