title: Predictive value of the Western Ontario and McMaster Universities Osteoarthritis Index for the amount of physical activity after total hip arthroplasty.
abstract: OBJECTIVE
  Despite the recognized health benefits of physical activity, little is known about the amount of physical activity that patients perform after total hip arthroplasty (THA). To this end, the ability of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) to predict the amount of physical activity that patients with a THA perform, as measured by the Short Questionnaire to Assess Health-Enhancing Physical Activity (SQUASH), was determined.
  
  
  METHODS
  Three hundred sixty-four patients who had a THA returned questionnaires. Pearson correlation coefficients were calculated between scores on the WOMAC and SQUASH. Binary logistic regression modeling was used to determine the extent to which the WOMAC score could predict that patients would meet national and international guidelines for health-enhancing physical activity.
  
  
  RESULTS
  Scores on the WOMAC and SQUASH showed a significant, but low, correlation (r=.14-.24). Although the WOMAC score was a significant predictor for meeting national and international guidelines for physical activity, the odds ratio was low (1.022, 95% confidence interval=1.012-1.033) and only 6.9% of the variance could be explained (Nagelkerke r(2)=.069).
  
  
  CONCLUSIONS
  The results suggest that the WOMAC is not suitable for predicting the amount of physical activity after THA, requiring the use of an additional outcome measure.
authors.affiliation: Department of Orthopedics, University Medical Center Groningen, University of Groningen, PO Box 30001, 9700 RB Groningen, the Netherlands. r.wagenmakers@orth.umcg.nl
authors.forename: Robert
authors.initials: R
authors.lastname: Wagenmakers
authors.forename: Martin
authors.initials: M
authors.lastname: Stevens
authors.forename: Inge
authors.initials: I
authors.lastname: van den Akker-Scheek
authors.forename: Wiebren
authors.initials: W
authors.lastname: Zijlstra
authors.forename: Johan W
authors.initials: JW
authors.lastname: Groothoff
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D015897:Comorbidity; D004185:Disability Evaluation; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000503:physiopathology* / Q000601:surgery*; D011237:Predictive Value of Tests; D012086:Reoperation; D011795:Surveys and Questionnaires