The Evaluation of FeNO for Predicting Response to ICS in Subjects With Non-specific Respiratory Symptoms

Nitric Oxide is recognized as a biological marker for many chronic airway diseases. It has been standardised for clinical use indicating airway inflammation. In clinical practice, FeNO can aid confirmation of an asthma diagnosis and can indicate the degree of steroid-responsiveness. This can help guide physician decisions on the initiation of inhaled corticosteroid (ICS) therapy, or adjustment of ICS therapy. Therefore, FeNO measurement could be particularly useful to confirm an asthma diagnosis in patients with non-specific respiratory symptoms (≥ 6 weeks of cough and/or wheezing and/or chronic dyspnoea) and to assess how likely they are to benefit from corticosteroid treatment. This study will assess the suitability of FeNO to predict ICS responsiveness in patients with non-specific respiratory symptoms. Additionally, we would like to determine the suitability of FeNO as a diagnostic tool for asthma in comparison to conventional predictors, e.g. spirometry.