School-aged asthma children with high fractional exhaled nitric oxide levels and lung dysfunction are at high risk of prolonged lung dysfunction.

Background: Long-term management of bronchial asthma based on the fractional exhaled nitric oxide (FeNO) value alone is not conclusive yet. Therefore, we combined FeNO testing and spirometry, a commonly used test in routine practice, to evaluate acute exacerbation and respiratory function in children with bronchial asthma.

Objective: We combined FeNO testing and spirometry, commonly used in routine practice, to evaluate acute exacerbations and respiratory function in children with bronchial asthma.

Methods: Subjects were school aged children 7 years and older with bronchial asthma who underwent FeNO testing in January 2015 to May 2016. We evaluated the changes in the frequency of acute exacerbations and respiratory function in the 30 subsequent months. Subjects were divided into 2 groups: those with initial FeNO levels ≥ 21 parts per billion (ppb) (high FeNO) and < 20 ppb (normal FeNO) groups.

Results: There were 48 children (33 boys) in the high FeNO group and 68 children (46 boys) in the normal FeNO group. Spirometry was conducted on 83 children (72%) prior to the initial FeNO test, revealing no difference in the ratio of detecting lung dysfunction between the 2 groups. The observation period was 25.8 ± 0.7 and 24.7 ± 0.6 months for the high and normal FeNO groups, respectively. The children in the high FeNO group with lung dysfunction in the initial FeNO test continued to exhibit lung dysfunction at the test at 30 months. In the normal FeNO group, even if lung dysfunction was observed at the initial FeNO, it improved within the 20-month point, and the improvement was maintained thereafter.

Conclusion: Children with bronchial asthma with high FeNO levels and lung dysfunction are at a higher risk of prolonged lung dysfunction.