Exhaled nitric oxide predicts airway hyper-responsiveness to hypertonic saline in children that wheeze.
BACKGROUND
Exhaled nitric oxide (eNO) has shown good validity for the assessment of airway inflammation in asthmatic children. In large-scale epidemiological studies, this method would be preferred above airway challenge tests, because it is a quick and easy applicable tool.


OBJECTIVE
In this study, we aimed to assess the discriminatory capacity of eNO, and prechallenge FEV1 for airway hyper-responsiveness (AHR) in 8-13-year old schoolchildren.


METHODS
Parents completed the ISAAC questionnaire, and children were tested for atopy, AHR to hypertonic (4.5%) saline (HS), and eNO. Diagnostic value was assessed by the area under the receiver operating curves (ROC), and calculation of positive and negative predicted values at different cut-off points for eNO and prechallenge FEV1.


RESULTS
Areas under the ROC-curves of AHR were 0.65 for eNO and 0.62 for FEV1. Values increased to 0.71 and respectively 0.75 for a combined occurrence of AHR and current wheeze. Highest sensitivity and specificity were obtained at a cut-off value of 43 ppb for eNO and 103% predicted for FEV1. At these cut-off values, the positive predictive values for the presence of AHR in symptomatic children were respectively 83% (eNO) and 33% (FEV1), and negative predictive values in asymptomatic children were, respectively, 90 (eNO) and 80% (FEV1).


CONCLUSIONS
Exhaled nitric oxide is a valid screening tool for AHR to HS in children that present with current wheeze, and it outperforms FEV1 as a predictor of AHR.
de Meer
G
G
Institute for Risk Assessment Sciences, Environmental & Occupational Health Unit, Utrecht University, Utrecht.
van Amsterdam
J G C
JG
Janssen
N A H
NA
Meijer
E
E
Steerenberg
P A
PA
Brunekreef
B
B
D000293:Adolescent; D016535:Bronchial Hyperreactivity / Q000209:etiology*; D002648:Child; D045853:Exhalation; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis* / Q000378:metabolism; D011237:Predictive Value of Tests; D012135:Respiratory Sounds / Q000209:etiology*; D012462:Saline Solution, Hypertonic
D012462:Saline Solution, Hypertonic; D009569:Nitric Oxide