title: Patient-reported outcomes in primary care patients with COPD: psychometric properties and usefulness of the Clinical COPD Questionnaire (CCQ). A cross-sectional study.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) is a common disease with considerable consequences for patients' daily lives. The Clinical COPD Questionnaire (CCQ) was designed to measure these consequences in daily practice. Although the CCQ is widely used, its original structure has never been tested.
  
  
  OBJECTIVE
  This study examines the psychometric properties of the CCQ with regard to its latent structure in a sample of primary care patients with COPD.
  
  
  METHODS
  Two cross-sectional studies were conducted; in study 1 (N=243) exploratory analyses, including exploratory factor analysis (EFA) and Mokken scale analysis, were performed to explore the latent structure of the CCQ. In study 2 (N=244), confirmatory factor analysis (CFA) was conducted to evaluate the model fit of the structure found in study 1.
  
  
  RESULTS
  Both EFA and Mokken scale analysis revealed a structure of two dimensions ('general impact' α=0.91 and 'cough' α=0.84). This structure, however, was not confirmed in study 2, nor was the original structure. However, subsequently removing items that violated the assumption of a normal response distribution did result in an excellent model fit with two dimensions measuring 'dyspnoea' and 'cough' (CFA: comparative fit index (CFI) 0.98; normed fit index (NFI) 0.97; root mean squared error of approximation (RMSEA) 0.08 (0.04)).
  
  
  CONCLUSIONS
  In primary care, factor analyses on the CCQ revealed a two-component structure measuring 'general impact', and 'cough'. A shortened and more specific version of the CCQ could be regarded as a useful instrument to screen for exacerbations by measuring dyspnoea, coughing and producing phlegm.
authors.affiliation: Department of Medical and Clinical Psychology, Centre of Research on Psychology in Somatic diseases (CoRPS), TSB, Tilburg University, Tilburg, The Netherlands.
authors.forename: Antoinette M
authors.initials: AM
authors.lastname: Pommer
authors.affiliation: Department of Medical and Clinical Psychology, Centre of Research on Psychology in Somatic diseases (CoRPS), TSB, Tilburg University, Tilburg, The Netherlands.
authors.forename: François
authors.initials: F
authors.lastname: Pouwer
authors.affiliation: Department of Medical and Clinical Psychology, Centre of Research on Psychology in Somatic diseases (CoRPS), TSB, Tilburg University, Tilburg, The Netherlands.
authors.forename: Johan
authors.initials: J
authors.lastname: Denollet
authors.affiliation: Revant, Pulmonary Rehabilitation Centre 'Schoondonck', Breda, The Netherlands.
authors.forename: Jan-Willem
authors.initials: JW
authors.lastname: Meijer
authors.affiliation: Department of Medical and Clinical Psychology, Centre of Research on Psychology in Somatic diseases (CoRPS), TSB, Tilburg University, Tilburg, The Netherlands.
authors.forename: Victor J
authors.initials: VJ
authors.lastname: Pop
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011320:Primary Health Care / Q000379:methods*; D011594:Psychometrics; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis*; D011795:Surveys and Questionnaires