title: Assessing health status in COPD. A head-to-head comparison between the COPD assessment test (CAT) and the clinical COPD questionnaire (CCQ).
abstract: BACKGROUND
  Health status provides valuable information, complementary to spirometry and improvement of health status has become an important treatment goal in COPD management. We compared the usefulness and validity of the COPD Assessment Test (CAT) and the Clinical COPD Questionnaire (CCQ), two simple questionnaires, in comparison with the St. George Respiratory Questionnaire (SGRQ).
  
  
  METHODS
  We administered the CAT, CCQ and SGRQ in patients with COPD stage I-IV during three visits. Spirometry, 6 MWT, MRC scale, BODE index, and patients perspectives on questionnaires were recorded in all visits. Standard Error of Measurement (SEM) was used to calculate the Minimal Clinical Important Difference (MCID) of all questionnaires.
  
  
  RESULTS
  We enrolled 90 COPD patients. Cronbach's alpha for both CAT and CCQ was high (0.86 and 0.89, respectively). Patients with severe COPD reported worse health status compared to milder subgroups. CAT and CCQ correlated significantly (rho =0.64, p < 0.01) and both with the SGRQ (rho = 0.65; CAT and rho = 0.77; CCQ, p < 0.01). Both questionnaires exhibited a weak correlation with lung function (rho = -0.35;CAT and rho = -0.41; CCQ, p < 0.01). Their reproducibility was high; CAT: ICC = 0.94 (CI 0.92-0.96), total CCQ ICC = 0.95 (0.92-0.96) and SGRQ = 0.97 (CI 0.95-0.98). The MCID calculated using the SEM method showed results similar to previous studies of 3.76 for the CAT, 0.41 for the CCQ and 4.84 for SGRQ. Patients suggested both CAT and CCQ as easier tools than SGRQ in terms of complexity and time considerations. More than half of patients preferred CCQ instead of CAT.
  
  
  CONCLUSIONS
  The CAT and CCQ have similar psychometric properties with a slight advantage for CCQ based mainly on patients' preference and are both valid and reliable questionnaires to assess health status in COPD patients.
authors.affiliation: Department of Thoracic Medicine, Medical School, University of Crete, Heraklion, Crete, PO 71003, Greece. i.tsiligianni@med.umcg.nl
authors.forename: Ioanna G
authors.initials: IG
authors.lastname: Tsiligianni
authors.forename: Thys
authors.initials: T
authors.lastname: van der Molen
authors.forename: Despoina
authors.initials: D
authors.lastname: Moraitaki
authors.forename: Ilaine
authors.initials: I
authors.lastname: Lopez
authors.forename: Janwillem W H
authors.initials: JW
authors.lastname: Kocks
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Karagiannis
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Siafakas
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Tzanakis
mesh_terms: D000368:Aged; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D057240:Patient Preference / Q000706:statistics & numerical data; D011594:Psychometrics; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D013147:Spirometry; D011795:Surveys and Questionnaires