Fractional exhaled nitric oxide and forced expiratory volume in 1 second/forced vital capacity have predictive value of asthma exacerbation in Korean school children.

Abstract

BackgroundThe incidence of asthma exacerbation (AE) and the predictive value of spirometry and fractional exhaled nitric oxide (FeNO) in school children have not been evaluated.ObjectiveWe sought to evaluate the efficacy of spirometry measurement and FeNO monitoring for predicting AE in school children in the Cheongju area in Korea.MethodsWith parental agreement, we studied 170 students aged 7–12 years. Children were evaluated by an asthma specialist using baseline spirometry, skin prick test, seasonal FeNO measurement, and asthma control test. The study participants underwent a physical examination and their medical history was also evaluated by the specialist. They were assessed for asthma control status during regular doctor visits for 1 year.ResultsIn total, 160 children (94.1%) completed follow-up and FeNO monitoring. Of which, 26 children (16.3%) had AE. AE was associated with male children and children with allergic rhinitis (p < 0.05). While, children with AE tended to have higher FeNO than those without AE, no significant difference was found. The maximum value of FeNO ≥35 ppb was associated with AE (p < 0.05). Children with AE had a significantly decreased baseline forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC), %predicted, forced expiratory flow at 25%–75% of FVC (FEF25%–75%). FEV1/FVC < 80% was associated with AE in children regardless of inhalant allergen sensitization (all p < 0.05).ConclusionBaseline spirometry had a predictive value of AE in school children. Sensitive spirometric parameters such as FEV1/FVC and FEF25%–75% can be used as prognostic factors to predict future childhood AE. FeNO value ≥ 35 ppb during monitoring was associated with AE in school children.