Influence of Sensitization Patterns on Fractional Exhaled Nitric Oxide in Asthmatic Children

Fractional exhaled nitric oxide (FeNO) has been suggested as a non-invasive biomarker of airway inflammation, which is increased in atopic subjects. Whether sensitization to particular allergens is a predictive factor for increased FeNO levels is not yet fully understood. We conducted a retrospective cross-sectional study. From October to December in 2015, the medical documents of 127 mild, steroid-naive asthmatic children and 34 healthy age-matched children were enrolled in this study. The results of the FeNO measurements, skin prick test, and the spirometry were collected for analysis. Sensitization patterns to the 18 aeroallergens (5 categories: mites, molds, animal dander, pollen, and other) were determined in study population. A significant increase in FeNO level was observed in poly-sensitized asthmatic children (34.7 part per billion, (ppb) [28.3-41.1 p.p.b]), compared with mono-sensitized asthmatics (30.7 p.p.b [18.3-43.2 p.p.b]) and with non-sensitized asthmatics (17.3 p.p.b [10.8-24.5 p.p.b]). With sensitization to perennial allergens (mites, mold, and animal dander), blood eosinophil counts were significantly associated with increased FeNO (p<0.05 for all). The highest FeNO level was identified in children sensitized to a combination of the perennial, seasonal, and other allergens, when compared with those sensitized to one category of allergen alone (p=0.004). Our study showed that variations in FeNO level were associated with individuals' sensitization patterns. Being sensitized to some particular allergens might contribute to prompt the airway inflammation.