Comparison of the COPD Assessment Test (CAT) and the Clinical COPD Questionnaire (CCQ) in a Clinical Population

Introduction: The COPD Assessment Test (CAT) and the Clinical COPD Questionnaire (CCQ) are both clinically useful health status instruments. The main objective was to compare CAT and CCQ measurement instruments. Methods: CAT and CCQ forms were completed by 432 randomly selected primary and secondary care patients with a COPD diagnosis. Correlation and linear regression analyses of CAT and CCQ were performed. Standardised scores were created for the CAT and CCQ scores, and separate multiple linear regression analyses for CAT and CCQ examined associations with sex, age (≤ 60, 61–70 and >70 years), exacerbations (≥1 vs 0 in the previous year), body mass index (BMI), heart disease, anxiety/depression and lung function (subgroup with n = 246). Results: CAT and CCQ correlated well (r = 0.88, p < 0.0001), as did CAT ≥ 10 and CCQ ≥ 1 (r = 0.78, p < 0.0001). CCQ 1.0 corresponded to CAT 9.93 and CAT 10 to CCQ 1.29. Both instruments were associated with BMI < 20 (standardised adjusted regression coefficient (95%CI) for CAT 0.56 (0.18 to 0.93) and CCQ 0.56 (0.20 to 0.92)), exacerbations (CAT 0.77 (0.58 to 0.95) and CCQ 0.94 (0.76 to 1.12)), heart disease (CAT 0.38 (0.17 to 0.59) and CCQ 0.23 (0.03 to 0.43)), anxiety/depression (CAT 0.35 (0.15 to 0.56) and CCQ 0.41 (0.21 to 0.60)) and COPD stage (CAT 0.19 (0.05 to 0.34) and CCQ 0.22 (0.07 to 0.36)). Conclusions: CAT and CCQ correlate well with each other. Heart disease, anxiety/depression, underweight, exacerbations, and low lung function are associated with worse health status assessed by both instruments.