title: Performance measures were necessary to obtain a complete picture of osteoarthritic patients.
abstract: OBJECTIVE
  Self-report questionnaires and performance measures represent two methods for assessing physical function. A recurring theme is that self-report measures are superior to performance measures. This study investigated the association between three performance test outcomes of four activities (pain, exertion, and time or distance; for self-paced walk, stair test, timed up-and-go, 6-minute walk) with self-reports of physical function (WOMAC Physical Function subscale and LEFS) and the association between the change scores of the performance tests and those of the self-report measures.
  
  
  METHODS
  Performance and self-report measures were administered three times (presurgery and at approximately 1 week and approximately 8 weeks post arthroplasty) to 85 patients who underwent total hip or knee arthroplasty. Components of the performance tests were pooled within each domain across the four measures. Multiple regression analyses were applied. Independent variables were performance tests components; dependent variables were self-report measures. Standardized regression coefficients described the cross-sectional and longitudinal associations.
  
  
  RESULTS
  Pain was the principal determinant of WOMAC Physical Function subscale scores. Pain, exertion, and time or distance were strongly associated with the LEFS at the first, second, and third assessments, respectively. Change in pain was most strongly associated with change in self-reported physical function.
  
  
  CONCLUSIONS
  Our findings caution against the isolated use of self-report assessments of physical function.
authors.affiliation: Clinical Epidemiology and Biostatistics, Faculty of Health Sciences, IAHS School of Rehabilitation Science, McMaster University, Hamilton, Ontario L8N 1C7, Canada. stratfor@mcmaster.ca
authors.forename: Paul W
authors.initials: PW
authors.lastname: Stratford
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Kennedy
mesh_terms: D000368:Aged; D019643:Arthroplasty, Replacement; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D005500:Follow-Up Studies; D005684:Gait; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000534:rehabilitation* / Q000601:surgery; D010147:Pain Measurement; D012044:Regression Analysis; D018709:Statistics, Nonparametric; D016896:Treatment Outcome