Validity and reliability of the Thai version of the leicester cough questionnaire in chronic cough

Background: Chronic cough is a common problem potentially disturbing the quality of life (QoL) of coughers. The Leicester Cough Questionnaire (LCQ), previously developed in England, is a validated, self-completed QoL instrument for assessment of chronic cough. This study aimed to develop a Thai version of the LCQ (LCQ-T) and assess its validity and reliability among adult Thai patients with subacute to chronic cough. Methods: A total of 146 patients with a cough lasting for more than 3 weeks consented to participate in this study and self-administered the LCQ-T, together with the following 3 instruments: Borg Cough Scale (BCS), Short Form-36 (SF-36), and Hospital Anxiety Depression Scale (Thai-HADS). The LCQ-T was developed by applying a forward-backward translation approach. The LCQ-T comprises 19 items divided into 3 domains: physical (8 items), psychological (7 items), and social (4 items). To validate the LCQ-T, concurrent validity, internal consistency reliability, and test-retest reliability were assessed. Results: Participants included 96 women and 50 men with a mean (SD) age of 59.6 (14.4) years. The concurrent validity comparing LCQ-T to BCS yielded statistically significant Pearson correlation coefficients (r= -0.74, P<0.05). The correlation coefficients for SF-36 and Thai-HADS were also significant. The LCQ-T demonstrated very good internal consistency in all domains and the overall scale, with the Cronbach's alpha coefficients ranging from 0.89 to 0.94. The 3-day repeatability of the LCQ-T in 25 clinically stable patients was high with the intra-class correlation coefficients ranging between 0.81 and 0.90. Conclusion: LCQ-T is a valid and reliable cough-specific instrument for assessing symptoms and QoL of adult Thai patients with subacute to chronic cough.