Abstract:

Objective    To explore the diagnostic value of fractional exhaled nitric oxide(FeNO)measurement in the diagnosis of bronchial asthma. Methods    A total of 118 patients with nonspecific respiratory symptoms were enrolled. 71 cases were diagnosed as bronchial asthma （group A）. 52 cases did not received a treatment with glucocorticoids(groupⅠ) and 19 cases received it for more than 4 weeks(groupⅡ). 47 cases were diagnosed as non-asthma(group B). FeNO was measured by a nitric oxide analyzer(NIOX; Aerocrine AB； Solna, Sweden). GINA (2006) was defined as the gold standard in the diagnosis of bronchial asthma. The value of FeNO was assessed and the optimal operating point of the FeNO testing was determined by the means of the receiver operating characteristic (ROC) curves. Results     Level of FeNO in groupⅠ was higher than that in groupⅡ［（72.92±50.26）ppb vs（35.74±27.53）ppb, P﹤0.05］ and group B ［（72.92±50.26）ppb vs（17.62±9.77）ppb, P﹤0.05］. The area under the ROC curve was 0.90. The optimal diagnostic cutoff point was 32.50ppb, which was capable of differentiating asthma and non-asthma with a sensitivity of 82.70% and a specificity of 87.90%.  Conclusion     The FeNO test may be helpful in the diagnosis of asthma with high sensitivity and specificity.

Key words: Asthma; Nitric oxide; Diagnosis; Diagnosis, differential; ROC curve