This study will use a combination of subjective and objective cough measures to assess the frequency of cough as well as its related morbidity in severe asthmatics. Comparisons will be made between T2-High, T2-Low and T2-intermediate patients defined using a composite biomarker profile (blood eosinophil count and FeNO) to assess the role of cough in each and these results will be compared to the transcriptomic and proteomic measurements in the RASP-UK where the same biomarker profiling is being used to define clinical sub-groups of severe asthma. This study aims to also improve characterisation of the T2-Low population and identify possible mechanisms for the pathophysiology of this group.
60 patients are expected to be recruited to the study. Patients will be provided with an information sheet and have a telephone follow-up after at least 24 hours to ask if they remain interested in participation and if so, they will then be asked back for a baseline visit.
Three groups of severe asthmatics will be recruited (as described in appropriate section) and undergo the following procedures:
* Demographic details, height, weight, spirometry, FeNO and vital signs
* Patient reported outcomes:
* Asthma Mini-Asthma Quality of Life Questionnaire (mini-AQLQ) - abbreviated version of Juniper AQLQ
* Asthma Control Questionnaire (ACQ-5 (5 questions);
* Leicester Cough Questionnaire, the Cough-specific quality-of-life Questionnaire and Cough Hypersensitivity Questionnaire will be used to assess the impact of cough;
* Visual analogue scales (VAS) for cough (VASc) and urge to cough (VASu) will be used as a measure of cough severity.
* Blood samples - a sample of blood will be taken for whole blood transcriptomic and serum analyses
* Citric acid cough challenge test will be used to measure cough reflex sensitivity in each phenotype.
* Spontaneous sputum sample - if patients produce a sputum sample during spirometry or citric acid challenge, this will be recorded and the sample will be retained for sputum differential cell count and storage of processed soluble components.
* On completing the above procedures, patients will be asked to wear a validated ambulatory cough monitor (Leicester Cough Monitor) for a 24-hour period to assess the frequency of cough and if they agree, will be fully instructed in its use.
Patients will be asked to attend a follow-up visit 2 weeks after baseline. The study procedures will remain the same as visit 1 with the exception of collection of clinical samples.
A mild/moderate population will be recruited and undergo the same procedures as the severe group in a baseline visit. No mild/moderate asthmatics will be asked to attend for a follow-up visit.
