B) Methods : 647 children aged 5 to 17 were enrolled. All subjects underwent skin prick test, pulmonary function test, and methacholine challenge test. Subjects were classified into 5 groups: 139 children with allergic rhinitis(AR), 83 children with non-allergic rhinitis(NAR), 18 children with asthma, 62 children with AR and asthma, and 345 control subjects. FeNO was then measured in all subjects.
C) Results : Mean level of FeNO in AR (32.3 ± 25.0 ppb), asthma (31.1 ± 20.5 ppb), and AR-asthma group (34.5 ± 30.4 ppb) was significantly higher as compared to that of NAR (16.8 ± 13.5 ppb) and control group (15.9 ± 12.5 ppb).(P<0.05) There was no significant difference in FeNO level among AR, asthma, and AR-asthma group. There was no significant difference in FeNO level between AR group with BHR and AR group without BHR. In skin prick test, mean level of FeNO in greater than or equal to 4+ group (36.6 ± 29.2 ppb) was significantly higher than that of 3+ group (27.6 ± 20.7 ppb). (P<0.01) In the ROC curve analysis for prediction of AR, when it showed 90% of positive predictive value, the cutoff level of FeNO was 50 ppb.
D) Conclusions : Level of FeNO has a significant correlation with allergic rhinitis. This result suggests that measurement of FeNO may be useful in the diagnosis of allergic rhinitis. And also, it suggests that there is relationship between allergic rhinitis and eosinophilic inflammation like asthma, although there is no expression of systemic eosinophilic reaction or bronchial hyper reactivity.