It was a retrospective, cross-sectional study. We evaluated data from medical documentation of children with atopic asthma who had performed standardized spirometric exercise challenge test.
One hundred and twenty six patients with atopic asthma, aged 5-18, were included in the analysis. There were two groups of patients: the EIB group (n = 54) and the no-EIB group (n = 72). The median FeNO level prior to exercise in the EIB group was 27.6 vs. 16.3 ppb in the no-EIB group (p = 0.002). FeNO level higher than 16 ppb had the highest diagnostic value to confirm EIB. When using the FeNO level of >16 ppb, the sensitivity, specificity, negative predictive and positive predictive values for EIB were 83 % , 46.9 % , 74.2 % , and 60 % , respectively. In the EIB group, the degree of FeNO elevation did correlate positively with the absolute fall in FEV1 (p = 0.002; r = 0.45). The FeNO value of >16 ppb, EBC value of >350 cell/mm3 and allergy to house dust mites presented the highest odds ratios of EIB. However, the FeNO value of >16 ppb was the only independent odds ratio of EIB.
Elevated FeNO level increased the odds of EIB in asthmatic schoolchildren, independently of other asthma severity markers and the intensity of anti-asthma therapy. It seems likely that FeNO measurement may act as a screening tool and help to prevent under-diagnosis and under-treatment of exercise-induced bronchoconstriction in schoolchildren with atopic asthma.