Pain and physical function are core outcome measures for people with osteoarthritis, and self-report questionnaires have been the preferred assessment method. The purpose of this study was to examine the factorial validity of performance-specific assessments of pain and function. The sample consisted of 177 participants who had osteoarthritis of the hip (n=81) or knee (n=96) and who were awaiting total joint arthroplasty. Participants performed 4 performance activities (self-paced walk test, stair test, Timed "Up & Go" Test, and Six-Minute Walk Test). Outcomes were time or distance (function) and pain ratings obtained immediately after each activity. It was found that collectively the walk test, Timed "Up & Go" Test, and Six-Minute Walk Test yielded 2 factors consistent with the health concepts of pain and function. The authors believe that the application of these tests may provide clinicians and clinical researchers with more distinct impressions of pain and function that complement information from self-report measures.
Physical Therapy, Vol. 86, No. 11, November 2006, pp. 1489-1496