The role of cough in severe asthma

Abstract

Rationale:
Cough is a common symptom within asthma that is both important and troublesome for patients and has been shown to be associated with a less well controlled disease. However, the role of cough within asthma is not well understood and there is little knowledge as to how cough is associated with typical markers of asthma disease control and severity.

Methods:
A series of studies were conducted to investigate how cough is associated with asthma. First, a systematic review to assess the extent to which cough has been studied within the asthma literature. Second, an observational study to investigate the associations of cough measurement tools with measures of asthma control, quality of life and associated inflammatory biomarkers. Third, a discrete choice experiment to gain an understanding of patient preferences for symptoms within asthma.

Results:
There are significant levels of cough burden within asthma with those with severe asthma being more affected by cough than those with mild/moderate asthma. Measures of cough-related quality of life are associated with measures of asthma control and can identify patients with inadequate asthma control. Cough measurement tools are suitable for repeated use within severe asthma. There appears to be a lack of significant levels of cough morbidity in patients where there is no evidence of raised Type 2 (T2) inflammation. Cough is an important symptom for patients with both severe and mild/moderate asthma and patients are willing to accept some additional asthma symptoms in order to reduce their cough burden.

Conclusions:
A significant level of cough morbidity can be identified in patients with asthma, even when not selecting for the symptom of cough. The use of cough measurement tools in asthma may provide additional insight into asthma control, quality of life and disease burden. However, as a significant level of cough burden was not observed in patients with low biomarkers of T2-inflammation, cough may not be suitable as a separate treatable trait in severe asthma. A logical first step for treating cough in severe asthma may be to achieve adequate suppression of T2 inflammation.

Date of Award	Jul 2021
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	Northern Ireland Department for the Economy
Supervisor	Liam Heaney (Supervisor) & Lorcan McGarvey (Supervisor)