title: Translation and validation of the Dutch version of the Effective Consumer Scale (EC-17).
abstract: OBJECTIVE
  The Effective Consumer Scale (EC-17) measures the skills of musculoskeletal patients in managing their own healthcare. The objectives of this study were to translate the EC-17 into Dutch and to further evaluate its psychometric properties.
  
  
  METHODS
  The EC-17 was translated and cognitively pretested following cross-cultural adaptation guidelines. Two hundred and thirty-eight outpatients (52 % response rate) with osteoarthritis or fibromyalgia completed the EC-17 along with other validated measures. Three weeks later, 101 patients completed the EC-17 again.
  
  
  RESULTS
  Confirmatory factor analysis supported the unidimensional structure of the scale. The items adequately fit the Rasch model and only one item demonstrated differential item functioning. Person reliability was high (0.92), but item difficulty levels tended to cluster around the middle of the scale, and measurement precision was highest for moderate and lower levels of skills. The scale demonstrated adequate test-retest reliability (ICC = 0.71), and correlations with other measures were largely as expected.
  
  
  CONCLUSIONS
  The results supported the validity and reliability of the Dutch version of the EC-17, but suggest that the scale is best targeted at patients with relatively low levels of skills. Future studies should further examine its sensitivity to change in a clinical trial specifically aimed at improving effective consumer skills.
authors.affiliation: Department of Psychology, Health and Technology, Arthritis Centre Twente, University of Twente, PO Box 217, 7500 AE, Enschede, The Netherlands. P.M.tenKlooster@utwente.nl
authors.forename: Peter M
authors.initials: PM
authors.lastname: ten Klooster
authors.forename: Erik
authors.initials: E
authors.lastname: Taal
authors.forename: Liseth
authors.initials: L
authors.lastname: Siemons
authors.forename: Johanna C M
authors.initials: JC
authors.lastname: Oostveen
authors.forename: Etelka J
authors.initials: EJ
authors.lastname: Harmsen
authors.forename: Peter S
authors.initials: PS
authors.lastname: Tugwell
authors.forename: Tamara
authors.initials: T
authors.lastname: Rader
authors.forename: Anne
authors.initials: A
authors.lastname: Lyddiatt
authors.forename: Mart A F J
authors.initials: MA
authors.lastname: van de Laar
mesh_terms: D000328:Adult; D000368:Aged; D003256:Community Participation; D003431:Cross-Cultural Comparison; D003469:Culture; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D017063:Outcome Assessment, Health Care; D011594:Psychometrics / Q000295:instrumentation*; D011788:Quality of Life / Q000523:psychology*; D015203:Reproducibility of Results; D012216:Rheumatic Diseases / Q000534:rehabilitation*; D011795:Surveys and Questionnaires; D014175:Translating; D014177:Translations