The validity and precision of the leicester cough questionnaire in COPD patients with chronic cough

BACKGROUND: A validated instrument to assess the effects of chronic cough on health status in patients with chronic obstructive pulmonary disease (COPD) is currently not available. The Leicester Cough Questionnaire (LCQ) is a cough-specific health status questionnaire which is originally validated for a population of general patients presenting with chronic cough. We examined the psychometric performance of the LCQ in patients with COPD and chronic productive cough. METHODS: Concurrent validity, internal consistency, reproducibility and responsiveness were determined. The St. George's Respiratory Questionnaire (SGRQ) and the Short Form-36 (SF-36) were used as external criteria. Questionnaires were completed at the start of the study. After 2 and 12 weeks the LCQ was repeated, together with a global rating of change. RESULTS: In total 54 patients were included. Concurrent validity analysis showed significant correlations between corresponding domains of the LCQ and the SGRQ (r(s )-0.31 to -0.60). Corresponding domains of the LCQ and the SF-36 showed weaker correlations (r(s )0.04 to 0.41). Internal consistency was adequate for two of the three domains (Cronbach's α 0.74 - 0.86). Test-retest reliability in stable patients was high (intraclass correlation coefficients 0.79 - 0.93). The mean difference after two weeks was 0.73 (± 1.75). Responsiveness analysis indicated that the LCQ was able to detect changes after 12 weeks. CONCLUSION: The LCQ is a valid, reliable, responsive instrument to measure health status in COPD patients with chronic productive cough. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01071161