Late Breaking Abstract - Predictive value of FeNO in patients with non-specific respiratory symptoms: a randomised controlled trial

Background: Fractional exhaled nitric oxide (FeNO) can predict treatment response in asthma, but little is known of its utility in patients with non-specific respiratory symptoms (NSRS). Aims and objectives: To evaluate the association between baseline FeNO and response to treatment with inhaled corticosteroids (ICS) in patients with NSRS. Methods: This was a multi-centre randomised, placebo-controlled trial, carried out in UK and Singapore. It consisted of a 2-week assessment period to establish baseline measurements and a 4-week treatment period with either extrafine ICS (200 µ beclomethasone bid) or placebo. NIOX VERO (Circassia) was used to measure baseline FeNO. The primary endpoint was change in ACQ7 score (Asthma Control Questionnaire, 7 questions). Analysis was carried out in a Main Analysis Set (MAS), which contained all randomised patients who complied with their study treatment and completed follow-up within 6 weeks of randomisation, and in a Per Protocol (PP) set, which included all patients in the MAS but excluded protocol violations. Results: In the PP set (n=214), we found that higher baseline FeNO was associated with a greater treatment effect. Improvement of ACQ7 was 0.071 (95% confidence interval [CI], 0.002-0.139) greater in patients receiving extrafine ICS compared to patients receiving placebo, for every 10 ppb increase in baseline FeNO. The equivalent effect was not significant in the MAS set (n=259) (0.049; 95% CI, -0.012-0.110). Conclusions: FeNO measurement is a simple, near patient, quantitative and non-invasive diagnostic tool that could support treatment decisions for patients with NSRS. Further research is needed to establish a treatment paradigm.