title: Confirmatory factor analysis of the Arthritis Impact Measurement Scales 2 short form in patients with rheumatoid arthritis.
abstract: OBJECTIVE
  To examine the factorial validity of the short form Arthritis Impact Measurement Scales 2 (AIMS2-SF) in patients with rheumatoid arthritis (RA).
  
  
  METHODS
  Data were from a sample of 279 patients with active RA who completed the long form AIMS2 before starting treatment with tumor necrosis factor alpha-blocking agents. Confirmatory factor analyses were conducted to test and compare the fit of the currently used theoretical measurement model of the AIMS2-SF, originally suggested for the long form AIMS2, and 2 alternative models based on previous exploratory research.
  
  
  RESULTS
  A model with the physical dimension divided into upper and lower body limitations was superior to the current model, and both models provided a clearly better fit than a model without a separate symptom dimension. Under the restrictive assumption of uncorrelated error terms, none of the models achieved a consistent and acceptable fit as judged by several goodness-of-fit indices. Allowing error covariances between 6 pairs of items within the same dimension resulted in an improved and acceptable fit of both the current model and the model with a separate upper and lower body component.
  
  
  CONCLUSIONS
  This study generally supports the factorial validity of the AIMS2-SF and suggests the use of separate scores for upper and lower body limitations. Further research is needed to resolve the issue of high error correlations associated with particular items.
authors.affiliation: Institute for Behavioral Research, Faculty of Behavioral Sciences, University of Twente, Enschede, The Netherlands. P.M.tenKlooster@utwente.nl
authors.forename: Peter M
authors.initials: PM
authors.lastname: ten Klooster
authors.forename: Martine M
authors.initials: MM
authors.lastname: Veehof
authors.forename: Erik
authors.initials: E
authors.lastname: Taal
authors.forename: Piet L C M
authors.initials: PL
authors.lastname: van Riel
authors.forename: Mart A F J
authors.initials: MA
authors.lastname: van de Laar
mesh_terms: D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000188:drug therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010043:Outcome and Process Assessment, Health Care; D015203:Reproducibility of Results; D016896:Treatment Outcome
chemical_list: D018501:Antirheumatic Agents