The validity and precision of the leicester cough questionnaire in COPD patients with chronic 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.ClinicalTrials.gov: NCT01071161COPD is a leading cause of morbidity and mortality all over the world. In 2001 COPD was the fifth cause of death and its relative importance is predicted to increase in future years [1,2]. Detection of airflow limitation is paramount in the GOLD definition of COPD [3,4], but clinically COPD is characterized by chronic and progressive dyspnea, cough and sputum production [4,5]. Prevalence rates of chronic productive cough in the male COPD population are estimated to be 15-44% and 6-17% in females. These rates increase with age and are strongly related to smoking [6]. The high prevalence of cough in COPD may be caused by increased production of mucus, by the inability to produce a sufficiently large expiratory flow leading to ineffective clearing of the mucus, and by impaired mucociliary clearance leading to mucus retention. Also, many patients with COPD have bronchiectasis [7,8].Chro