WAO-ARIA consensus on chronic cough - Part II: Phenotypes and mechanisms of abnormal cough presentation - Updates in COVID-19

Affiliations


Abstract

Background: Chronic cough can be triggered by respiratory and non-respiratory tract illnesses originating mainly from the upper and lower airways, and the GI tract (ie, reflux). Recent findings suggest it can also be a prominent feature in obstructive sleep apnea (OSA), laryngeal hyperresponsiveness, and COVID-19. The classification of chronic cough is constantly updated but lacks clear definition. Epidemiological data on the prevalence of chronic cough are informative but highly variable. The underlying mechanism of chronic cough is a neurogenic inflammation of the cough reflex which becomes hypersensitive, thus the term hypersensitive cough reflex (HCR). A current challenge is to decipher how various infectious and inflammatory airway diseases and esophageal reflux, among others, modulate HCR.

Objectives: The World Allergy Organization/Allergic Rhinitis and its Impact on Asthma (WAO/ARIA) Joint Committee on Chronic Cough reviewed the current literature on classification, epidemiology, presenting features, and mechanistic pathways of chronic cough in airway- and reflux-related cough phenotypes, OSA, and COVID-19. The interplay of cough reflex sensitivity with other pathogenic mechanisms inherent to airway and reflux-related inflammatory conditions was also analyzed.

Outcomes: Currently, it is difficult to clearly ascertain true prevalence rates in epidemiological studies of chronic cough phenotypes. This is likely due to lack of standardized objective measures needed for cough classification and frequent coexistence of multi-organ cough origins. Notwithstanding, we emphasize the important role of HCR as a mechanistic trigger in airway- and reflux-related cough phenotypes. Other concomitant mechanisms can also modulate HCR, including type2/Th1/Th2 inflammation, presence or absence of deep inspiration-bronchoprotective reflex (lower airways), tissue remodeling, and likely cough plasticity, among others.

Keywords: COVID 19; Cough phenotypes; Lower airway disease; Multifactorial cough; Obstructive sleep apnea; Reflux-cough; Type 2 inflammation; Upper airway cough syndrome.

Conflict of interest statement

•Jean Bousquet discloses financial relationships with the following entities: Purina, Chiesi, Cipla, Hikma, Menarini, Mundipharma, Mylan, Novartis, Sanofi-Aventis, Takeda, Teva, Uriach, KyoMed, MASK-air.•Glenis Scadding discloses payment for talks from ALK, Bayer, GSK and Viatris. She is also chair/member of 3 Data Monitoring Committees for ALK.•Jonathan A. Bernstein discloses he is PI and consultant and speaker for Merck.•Erika Jensen-Jarolim discloses honoraria and support to attend meetings from Bencard Allergie, Germany, and Allergy Therapeutics Ltd, UK; a pending patent and stock or stock options with Biomedical Int. R + D GmbH, Vienna; participation on data monitoring or advisory boards with Allergy Therapeutics Ltd, UK; and receipt of equipment, materials, drugs, medical writing, gifts or other services from Bencard Allergie, Germany.•Giorgio Walter Canonica discloses speaker or advisory board roles with Menarini, Chiesi, Sanofi, GSK, AstraZeneca, Novartis, Stallergenes, Hall, Allergy Therapeutics.•All other authors indicated they have nothing to disclose related to the submitted work.
 


References

https://pubmed.ncbi.nlm.nih.gov/