Cough symptom score was adapted for Korean conditions following a forward-backward translation procedure. All patients referred to chronic cough clinics of 5 university hospitals between May 2011 and October 2013 completed two questionnaires, the LCQ and the Short-Form 36 (SF-36) upon presentation and completed Leicester Cough Questionnaire (LCQ) and the Global Rating of Change upon follow-up visits with two or four weeks intervals. Concurrent validation, internal consistency, repeatability and responsiveness were determined.
For the concurrent validation, the correlation coefficients (n = 202 patients) between the cough symptom score and LCQ varied between -0.66 and -0.60 and between cough symptom score and VAS varied between -0.51 and -0.58. The internal consistency of the cough symptom score (n = 207) evaluated as correlation between scores of night and day symptoms was 0.24 (p=0.0006). The repeatability of the cough symptom score in patients with no change in cough (n = 23) was high with intra-class correlation coefficients varying between 0.66 and 0.81. Patients who reported an improvement in cough (n = 30) on follow-up visits demonstrated significant improvement on each of the domains of the cough symptom score.
The Korean version of cough symptom score is a valid and reliable method to measure severity of chronic cough.