Association of longitudinal fractional exhaled nitric oxide measurements with asthma control in atopic children

Abstract

We sought to determine whether longitudinal measurements of FeNO are informative for future loss of asthma control in children with atopic asthma. One hundred seventy-eight patients aged 8-16 years with atopic asthma were enrolled. FeNO and lung functions were serially monitored 10 times or more over 2 years when subjects were not receiving controller medications. After completion of monitoring, 1-year observation on the occurrence of loss of asthma control was performed and associations of loss of asthma control with spirometric and FeNO measurements were analyzed. Loss of asthma control occurred during observation periods in 110 (76%) of 145 patients who completed the study. Of all monitored parameters including airway reactivity, the highest FeNO of serial measurements (H-FeNO) (adjusted odds ratio (aOR), 1.21; 95% CI, 1.08-1.36) and the rate of FeNO levels higher than 21ppb (R21FeNO) (aOR, 1.06; 95% CI, 1.01-1.11) were the only independent predictors of upcoming control loss in the multiple logistic regression analysis. In receiver-operator characteristic curve analysis, H-FeNO>37ppb and R21FeNO>20% demonstrated 91% and 88% sensitivity for a future loss of asthma control at the cost of low specificity (60% and 65%, respectively). In contrast, H-FeNO>47ppb and R21FeNO>41% gave 96% and 88% specificity, but these sacrificed sensitivity to 70% and 72%, respectively. Our data show that both amount and frequency of a FeNO increase during longitudinal monitoring are helpful in predicting asthma control status.