Biomarkers of airway inflammation: The use of exhaled nitric oxide (FeNO) in the management of adult asthma in UK primary care

Rationale: Current asthma guidelines recommend reducing inhaled corticosteroid (ICS) therapy dose by 50% in patients with mild to moderate asthma who have demonstrated three months of good symptom control however there is evidence to suggest that this does not occur. Objectives: We tested whether exhaled nitric oxide (FeND) measurements or other clinical indices could be utilised to predict a safe reduction of ICS dose, without provoking loss of symptom control or exacerbation within 3 months. We also investigated relationships between airway inflammation and asthma symptoms in the mild to moderate asthma cohort. Methods: 191 patients with stable asthma were recruited from primary care. Patients had their FeND level measured at baseline and then had their inhaled corticosteroid (ICS) dose reduced by 50%. FeND measurements were reassessed seven days later. The primary outcomes were whether baseline FeND or a change in FeND following ICS dose reduction could predict asthma stability at 3 months. Results: 128/191 patients (67%) completed the ICS dose reduction successfully at three months. 63/191 patients (33%) suffered from either a loss of control or an exacerbation. Baseline FeND, or change in FeND (post step-down minus pre step-down) were not statistically significantly different between the two groups. Conclusion: 67% of patients with well-controlled asthma can safely reduce their ICS dose by half without suffering from a loss of control or exacerbation within three months; however neither baseline nor change in FeND measurements or routine clinical indices can be used to predict which patients can or cannot successfully tolerate a reduction in ICS dose.EThOS - Electronic Theses Online ServiceGBUnited Kingdo