Exhaled Nitric Oxide in Children with Allergic Rhinitis and/or Asthma: A Relationship with Bronchial Hyperreactivity

Background. Nowadays, the measure of the fractional concentration of exhaled nitric oxide (FeNO) enables to assess airway inflammation during an office visit and there is international consensus on this testing methodology. The aim of this study was to evaluate whether FeNO measurement is predictable for bronchial hyperreactivity (BHR) in children with allergic rhinitis, asthma, or both. Methods. Two hundred and eighty children with allergic rhinitis, allergic asthma, or both were evaluated. Bronchial function (FEV1 and FEF25-75), BHR (assessed by methacholine challenge), FeNO, and sensitizations were assessed. Results. Bronchial function, BHR, and FeNO were significantly different in the three groups (p < .001). A strong inverse correlation between FeNO and BHR was found in patients with asthma and with asthma and rhinitis (r = -0.63 and r = -0.61, respectively). A cutoff of 32 ppb of FeNO was a predictive factor for BHR. Conclusions. This study highlights the relevance of FeNO as possible marker for BHR in allergic children and underlines the close link between upper and lower airways.