Evaluation of the Validity of Fractional Exhaled Nitric Oxide for Screening Airway Hyperresponsiveness in Patients with Chronic Cough

Objective:To evaluate whether fractional exhaled nitric oxide(FeNO) can be used to screen airway hyperresponsiveness(AHR) in patients with chronic cough.Methods:A total of 73 patients with chronic cough had undergone bronchial provocation test and the test of FeNO level.Results: The results of bronchial provocation test were positive in 35 cases(positive group) and negative in 38 cases(negative group).The FeNO level in the positive group [(50.20±47.36) ppb] was significantly higher than that in the negative group [(15.08±5.20) ppb],P0.05.The area under receiver operating characteristic(ROC) curve was 0.905;the optimal cutoff value of FeNO was 22.5ppb with sensitivity of 71.43%,specificity of 97.37%,positive predictive value of 96.15% and negative predictive value of 78.72%.Conclusion: FeNO level can be used to screen AHR with a high sensitivity and specificity,and thus it contributes to the differential diagnosis of chronic cough.