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The online version of this article (doi:10.1186/1477-7525-10-4) contains supplementary material, which is available to authorized users.
The authors declare that they have no competing interests.
FFB contributed to data collection, analysis and interpretation of the data and was primarily responsible for writing the manuscript, LNB and NEH contributed to data collection, analysis and interpretation of the data and critical revision of the manuscript. SMU contributed to the design of the study, analysis and interpretation of the data and critical revision of the manuscript. HAMK and JWKB contributed to the design of the study, interpretation of the data and critical revision of the manuscript. All authors read and approved the final manuscript.
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.
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.
In total 54 patients were included. Concurrent validity analysis showed significant correlations between corresponding domains of the LCQ and the SGRQ (rs -0.31 to -0.60). Corresponding domains of the LCQ and the SF-36 showed weaker correlations (rs 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.
The LCQ is a valid, reliable, responsive instrument to measure health status in COPD patients with chronic productive cough.