Evaluating the Clinical COPD Questionnaire: A systematic review

The Clinical COPD Questionnaire (CCQ) is recommended by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) to evaluate health status in patients with COPD. The objective of this work was to systemically assess the reliability, validity, responsiveness and minimum clinically important difference (MCID) of the CCQ. A structured search was conducted in three databases to identify articles that evaluated the psychometric properties of the CCQ in individuals with COPD. Two investigators screened the title, abstract and full text of the articles to determine study eligibility and performed the data extraction. Quality assessment of included studies was assessed by the COSMIN (Consensus-Based Standards for the Selection of Health Measurement Instruments) checklist. Finally, 43 studies were included, over half of which had fair methodological quality. Internal consistency (reliability) of the CCQ total score ranged from 0.84 to 0.94, and test-retest reliability was 0.70-0.99. The overall CCQ had a better correlation with St George's Respiratory Questionnaire (SGRQ; from 0.71 to 0.88) and COPD Assessment Test (CAT; from 0.64 to 0.88) than modified Medical Research Council (mMRC; from 0.392 to 0.668) and forced expiratory volume in 1 s (FEV₁ % predicted; from -0.31 to -0.68). Scores were different within GOLD stages, groups, composite events and co-morbidities. CCQ was sensitive to exacerbations, pulmonary rehabilitation and smoking cessation with the MCID of 0.4. The CCQ is a very useful and practical tool that can be used in clinical populations with good reliability, validity and responsiveness to interventions.