Nitric Oxide Correlates with Exercise-Induced Bronchoconstriction in Asthmatic Children / 소아알레르기및호흡기학회지

ABSTRACT

PURPOSE: Exercise-induced bronchoconstriction (EIB) affects daily activities as well as school performance in children. Exhaled nitric oxide (eNO) is a noninvasive test that measures airway inflammation in asthmatics. The aim of this study was to address the relationship between eNO and childhood EIB. METHODS: Our study consisted of 101 children aged 6 to 18 years belonging to one of three groups, asthmatic children with EIB (n=31), asthmatic children without EIB (n=28), or healthy controls (n=42). After children were taken off drugs that treated their asthma, baseline (pre-exercise) eNO and biomarkers of inflammation were measured. All subjects underwent spirometry and the bronchial challenge by methacholine inhalation and outdoor free running. RESULTS: eNO levels in asthmatic children with EIB were significantly greater than those in both asthmatic children without EIB (P=0.012) and controls (P<0.001). The median eNO (interquartile range) levels were 26.0 (15.0 to 46.0) parts per billion (ppb) in asthmatic children with EIB, 16.0 (12.5 to 28.0) ppb in asthmatic children without EIB, and 12.0 (10.0 to 15.3) ppb in controls. Post-exercise decrease of forced expiratory volume in 1 second correlated positively with eNO (r=0.637, P<0.001; r, partial correlation coefficient adjusted for age and height). The cutoff value for prediction of significant EIB was 20 ppb, and the overall sensitivity, specificity, positive predictive value, and negative predictive values were 61.3%, 80.0%, 57.6%, and 82.4%, respectively. The area under the receiver operating characteristic curve was 0.767 (95% confidence interval, 0.661 to 0.874). CONCLUSION: Baseline eNO levels correlate with the post-exercise decrease of forced expiratory volume in 1 second, suggesting that eNO may be a tool in the prediction of EIB.