Validation of the Clinical COPD Questionnaire (CCQ) in primary care

Background: Patient centred outcomes, such as health status, are important in Chronic Obstructive Pulmonary Disease ( COPD). Extensive questionnaires on health status have good measurement properties, but are not suitable for use in primary care. The newly developed, short Clinical COPD Questionnaire, CCQ, was therefore validated against the St George's Respiratory Questionnaire (SGRQ). Methods: 111 patients diagnosed by general practitioners as having COPD completed the questionnaires twice, 2-3 months apart, without systematic changes in treatment. Within this sample of patients with "clinical COPD" a subgroup of patients with spirometry verified COPD was identified. All analyses was performed on both groups. Results: The mean FEV1 (% predicted) was 58.1% for all patients with clinical COPD and 52.4% in the group with verified COPD (n = 83). Overall correlations between SGRQ and CCQ were strong for all patients with clinical COPD (0.84) and the verified COPD subgroup (0.82). The concordance intra-class correlation between SGRQ and CCQ was 0.91 (p < 0.05). Correlations between CCQ and SGRQ were moderate to good, regardless of COPD severity. Conclusion: The CCQ is a valid and reliable instrument for assessments of health status on the group level in patients treated for COPD in primary care but its reliability may not be sufficient for the monitoring of individual patients.