Cross-cultural adaptation and validation of Leicester Cough Questionnaire in sarcoidosis: the persian version

Cough is a common symptom among patients with sarcoidosis, and the Leicester Cough Questionnaire, a cough-specific quality-of-life measure, evaluates the impact of cough across physical, psychological, and social domains in patients with chronic cough. The aim of this study was cross-cultural adaptation and validation of Persian version of Leicester Cough Questionnaire (LCQ) in pulmonary sarcoidosis in Iran.

Psychometric analyses included translation and back translation of the questionnaire, face validity, content validity, construct validity, criterion-related validity, internal consistency, and test -retest reliability were performed.

Twenty-five participants demonstrated no major language barriers or difficulties in completing the questionnaire and adequate face validity of ≥1.5. Twelve experts confirmed the content validity was good (CVR˃0.56, I-CVI≤0.79, S-CVI/Ave˃0.80). Totally, 190 patients were included in the study. The Pearson's coefficients and their significance's (P<0.05) showed an acceptable agreement between the LCQ and the SF-36 questionnaire. The goodness-of-fit of the conceptual model including psychological, physical, and social domains, obtained from EFA, was confirmed throughout the RMSEA of 0.09 (<0.1), NFI of 0.9, NNFI of 0.91, and CFI of 0.92 which all were ≥0.9. The Persian LCQ showed an excellent internal consistency regarding Cronbach's alpha of 0.974 and ICC (95%CI) value of 0.983 (0.977, 0.987).

The psychometric properties showed that the Persian version of LCQ is a valid and reliable measure to evaluate cough-specific quality of life and is a fit-for-purpose measure for use in patients with pulmonary sarcoidosis and the results can guide clinicians in treatment decisions.