Combined Use of Fractional Exhaled Nitric Oxide and Bronchodilator Response in Predicting Future Loss of Asthma Control Among Children with Atopic Asthma

Background: The aim of the present study was to see whether measurements of bronchodilator response (BDR) and fractional exhaled nitric oxide (FeNO) in combination are informative for upcoming loss of asthma control among children with atopic asthma.

Methods: Two hundred one patients aged 8 to 16 years with atopic asthma were recruited. Pulmonary function tests including BDR and FeNO were serially measured 10 times or more over 2 years when subjects were not receiving controller medications. After completion of monitoring, 1-year observation for loss of asthma control was performed.

Results: At least 1 positive BDR (≥12% improvement in FEV₁ in response to inhaled short-acting b₂-agonist) and high maximum FeNO (mFeNO) (≥ 35 parts per billion (ppb)) were confirmed over the 2-year observation period in 59% and 77% of study participants. There was no difference in FeNO levels between individuals with positive and negative BDRs. Risk of asthma control loss increased by 40% for patients with mFeNO ≥ 35 ppb [Hazard ratio (HR) = 1.94; P < 0.01], and by 26% for those with positive BDRs (HR = 1.40; P < 0.01). Risk of asthma control loss was greatest for patients with either (HR = 5.31; P < 0.01) or both positive BDRs and mFeNO ≥ 35 ppb (HR = 5.65; P< 0.01).

Conclusions: High FeNO was better able to predict upcoming loss of asthma control than BDRs, but use of both markers together provided a better indicator of asthma control loss.