Background: Chronic cough has negative effects on quality of life. However, the changes in health-related quality of life and clinical implications remain unclear in Chinese patients with chronic cough.
Methods: A standard Chinese version of Leicester cough questionnaire (LCQ) was developed by an established translation procedure and its repeatability was assessed in a preliminary study involving 20 untreated patients with stable chronic cough. The quality of life was measured with the Short form-36 health survey and compared between 110 patients with chronic cough and 90 healthy volunteers. The changes in health-related quality of life were evaluated in the patients with chronic cough with the LCQ just before the specific treatment was initiated and a week after the cough had resolved completely. Cough threshold with inhaled capsaicin, expressed as the lowest concentration of capsaicin required for the induction of > or = 5 coughs, was also measured.
Results: The repeatability of the Chinese version of the LCQ was validated at a four day interval with the intraclass correlation coefficients of 0.89-0.94 for total and domain score (n = 20). The scores of the Short form-36 health survey were significantly lower in patients with chronic cough than those in healthy volunteers. In general, there was no significant difference in overall quality of life between different causes of chronic cough or genders although embarrassment, frustration and sleep disturbance were more common in female patients, as indicated by the LCQ. However, the successful treatment of cough obviously increased the total scores of the LCQ from 14.2 +/- 2.7 to 19.5 +/- 1.9 (t = 13.7, P < 0.0001). There was a significant correlation between the total score of the LCQ and physical (r = 0.39, P < 0.0001) or mental (r = 0.30, P < 0.001) component summary of the Short form-36 health survey but not between the LCQ and capsaicin cough threshold.
Conclusion: The quality of life is significantly impaired in Chinese patients with chronic cough. The Chinese version of the LCQ is a valid measure of cough related quality of life and is repeatable and responsive.