title: Assessment of the test-retest reliability and construct validity of a modified Lequesne index in knee osteoarthritis.
abstract: OBJECTIVE
  To assess the test-retest reliability and the construct validity of a modified version of the Lequesne index.
  
  
  METHODS
  Patients with symptomatic knee osteoarthritis (OA) fulfilling the revised criteria of the American College of Rheumatology completed the Lequesne index twice at a 3-h interval. Impairment outcome measures and patients' perceived discomfort in walking and handicap were recorded. An item-by-item analysis was performed. Items having insufficient psychometric properties were excluded. Test-retest reliability was assessed using the intra-class correlation coefficient (ICC) and the Bland and Altman method. Construct validity was investigated using Spearman rank correlation coefficient and a factor analysis was performed.
  
  
  RESULTS
  Eighty-eight patients were included. One question assessing pain (question IE) had a weak reliability (Kappa (kappa) = 0.39) and was excluded. The test-retest reliability of the modified questionnaire was excellent (ICC = 0.95). Expected convergent and divergent correlations were achieved except for visual analog scale pain (VAS P) and VAS handicap (VAS H) (0.46 and 0.40, respectively), and the "a priori" double stratification was confirmed by factor analysis, explaining 48.7% of the variance.
  
  
  CONCLUSIONS
  The modified form of the Lequesne index has sufficient psychometric properties to be used to assess pain and function in knee OA in a French population.
authors.affiliation: Department of Physical and Rehabilitation Medecine, Hôpital Cochin AP-HP, Université René Descartes, Paris, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Faucher
authors.forename: Serge
authors.initials: S
authors.lastname: Poiraudeau
authors.forename: Marie Martine
authors.initials: MM
authors.lastname: Lefevre-Colau
authors.forename: François
authors.initials: F
authors.lastname: Rannou
authors.forename: Jacques
authors.initials: J
authors.lastname: Fermanian
authors.forename: Michel
authors.initials: M
authors.lastname: Revel
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018771:Arthralgia / Q000209:etiology; D005260:Female; D005602:France; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D010147:Pain Measurement / Q000379:methods*; D011594:Psychometrics / Q000379:methods; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D016138:Walking