Thurston Arthritis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Center for Health Services Research in Primary Care, Department of Veterans Affairs Medical Center, Durham, NC, USA. Electronic address: kdallen@email.unc.edu. Thurston Arthritis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Division of Physical Therapy, Department of Allied Health Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. Thurston Arthritis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Division of Physical Therapy, Department of Allied Health Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Injury Prevention Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.