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Cough, asthma and airways inflammation

Rationale Cough is an important symptom in asthma. In addition, cough is both troublesome to patients and may be important in the development of more severe disease. Moreover, it is a key symptom in the diagnosis of asthma, according to international guidelines. Little is known regarding the mechanism of cough in asthma. Until now, subjective measures of cough have been used in mechanistic and therapeutic studies relating to both cough in asthma and chronic cough. There is no published literature documenting cough rates in asthma or the relationship between cough rates and both subjective measures of cough and asthma control. In addition, the relationship between objective cough rates and airway inflammation, and the effects of cough on airway function and inflammation is unknown. Methods A series of studies was designed and carried out to answer the above questions. Firstly, a cross sectional study examining the relationships between objective and subjective measures of cough in classical asthma (CA), secondly a longitudinal study examining the relationship between cough rates and CA control and thirdly a cross-sectional study examining the effects of voluntary cough on airway function and inflammation. Results There was a poor correlation between objective and subjective measures of cough in CA. Cough-related quality of life correlated most closely with cough rates. Traditional measures of CA (e.g. spirometry) poorly reflected cough rates. Objective cough rates and sputum eosinophils were predictive of CA control as defined by ACO. Objective cough rates did not reflect sputum inflammatory cell count or mediators. Voluntary cough induced small changes in peak flow in mildmoderate CA and small changes in sputum ECP that were not reflected by changes in sputum eosinophils. Conclusions Subjective measures of cough in asthma are poor substitutes for objective cough rates. When designing studies for cough in asthma, both objective cough rates and cough-related quality of life should be incorporated. Objective cough rates reflect asthma control (independent of airway inflammation) more closely than traditional measures of asthma. Airway inflammation does not appear to directly reflect cough rates. In addition, short bouts of coughing in mildmoderate asthma induce neither significant changes in airway function nor airway inflammation.
Date January 2010
CreatorsMarsden, Paul Anthony
PublisherUniversity of Manchester
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation

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