Assessing health status in COPD. A head-to-head comparison between the COPD assessment test (CAT) and the clinical COPD questionnaire (CCQ)

Abstract

BackgroundHealth 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).MethodsWe 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.ResultsWe 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.ConclusionsThe 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.

Validation of the COPD Assessment Test in Patients with COPD in Iran

“…Results of these studies indicated that there is strong evidence for the questionaries' content validity, internal consistency and correlation with similar instruments. In another study in Netherlands, the CAT, CCQ and SGRQ were completed by 90 COPD patients in stage I-IV during three visits and compared with each other [16]. This study showed that the CAT and CCQ both had acceptable validity, reliability and repeatability.…”

Critical Steps: A Non-Interventional, Multicenter, Prospective, Observational Study on Critical Handling Errors with DPI Use, in Asthma and COPD Patients

“…The former changes are also clinically important since the minimum clinically important difference has been reported to range between 2-3.76 points [21][22][23].…”

“…CAT appears to behave the same way across countries [20]. The minimum clinically important difference has been estimated to range between 2 [21] to 3.76 [22,23] points.…”

Health status assessment in COPD

“…The MCID is defined as "the smallest difference in a measurable clinical parameter that indicates a meaningful change in the condition for better or for worse, as perceived by the patient, clinician or investigator" (70). A MCID is also frequently used to perform a sample size calculation, assess the efficacy of specific therapies and to assist in interpreting statistical significant results (71,72). To estimate a MCID, anchor-and distribution-based approaches can be applied (71).…”

“…A MCID is also frequently used to perform a sample size calculation, assess the efficacy of specific therapies and to assist in interpreting statistical significant results (71,72). To estimate a MCID, anchor-and distribution-based approaches can be applied (71). Multiple studies looked at MCIDs for health status questionnaires.…”