Is laryngeal hypersensitivity the basis of unexplained or refractory chronic cough?

Refractory chronic cough (RCC) and unexplained chronic cough (UCC) are common problems seen in primary care and subspecialty clinics. The role of cough hypersensitivity and laryngeal dysfunction in contributing to the persistence of cough in RCC/UCC is not well recognised. Data of patients with RCC and UCC evaluated in 2019 by an interdisciplinary cough clinic led by a pulmonologist and speech-language pathology team was reviewed. Patients completed validated questionnaires including the Leicester cough questionnaire (LCQ), voice handicap index (VHI) and dyspnoea index (DI) questionnaire at initial encounter. Presence of cough hypersensitivity was based upon a history of allotussia and hypertussia. Laryngeal dysfunction was diagnosed in those with a history of laryngeal paresthesias, throat clearing, voice abnormalities, upper airway dyspnoea and documentation of functional or anatomic laryngeal abnormalities on nasoendoscopy. Of the 60 UCC/RCC patients analysed, 75% of patients were female and 85% were over 40 years of age. Cough hypersensitivity was documented in all patients and multiple cough triggers occurred in 75% of patients. 95%, 50% and 25% of patients reported laryngeal paresthesias, voice abnormalities and upper airway dyspnoea, respectively. Significant associations between LCQ and VHI and DI scores occurred when adjusting for age, sex, ethnicity and body mass index. Laryngeal functional abnormalities were documented on 44 out of 60 patients on nasoendoscopy. Hypertussia, allotussia and laryngeal dysfunction are common in patients with RCC and UCC. Evaluation of UCC and RCC can delineate laryngeal hypersensitivity and allows appropriate treatment to be directed at this phenotype.
Competing Interests: Conflict of interest: K.M. Sundar attended one advisory board for Merck in August 2020 ($1175.00), was a site principal investigator (PI) for a study on iVAPS validation of an expiratory positive airway pressure algorithm funded by Resmed Inc., received nonfinancial support for a study on sham continuous positive airway pressure in chronic cough from Respironics Inc., and was a site PI for VOLCANO-2 funded by NeRRe Therapeutics Inc., outside the submitted work. Conflict of interest: A.C. Stark has nothing to disclose. Conflict of interest: N. Hu has nothing to disclose. Conflict of interest: J. Barkmeier-Kraemer has nothing to disclose.
(©The authors 2021.)