The development of the Cough Hypersensitivity Questionnaire for chronic cough.

Introduction: Chronic cough is considered a disorder of neuronal hypersensitivity in which patients frequently report abnormal laryngeal and chest sensations, and excessive triggers. To facilitate clinical assessment, we developed the Cough Hypersensitivity Questionnaire (CHQ). Methods: Candidate questionnaire items were developed following interviews with patients with refractory chronic cough (n=10, United Kingdom), and review by a multidisciplinary team. The CHQ was evaluated in individuals with chronic cough (n=535, UK/South Korea), for unidimensionality and differential item functioning (with Rasch analysis), internal consistency, concurrent validity (against cough severity visual analogue scale (VAS) and Leicester Cough Questionnaire (LCQ) scores), and content validity (cognitive debriefing interviews, n=13). Results: Concept elicitation created a pool of 34 items. Eleven items were removed following multidisciplinary team review of patient interviews. Rasch analysis confirmed the CHQ total score to be a unidimensional scale; one item was removed due to differential item functioning. The final 22 binary-item CHQ comprises 6 sensation-related and 16 trigger-related items. Median (interquartile range) total CHQ scores were 9 (6-12); sensations 4 (2-5) and triggers 5 (3-8). Internal consistency was good (person separation index 0.74). The CHQ total score was moderately associated with cough severity VAS (0.42, p=0.005) and LCQ total score (ρ=-0.52, p<0.001). In cognitive debriefing, patients found that the CHQ was relevant to their condition and simple to complete. Conclusion: The CHQ is simple to use and has validity for assessing cough triggers and sensations in patients with chronic cough. Further studies are needed to assess its repeatability, responsiveness and clinical utility.