Predictive Value of Fractional Exhaled Nitric Oxide of Airway Eosinophilic Infalmmation in Chronic Cough and Classic Asthma

SESSION TITLE: Asthma II SESSION TYPE: Original Investigation Poster PRESENTED ON: Saturday, April 16, 2016 at 11:45 AM - 12:45 PM PURPOSE: To investigate the predictive value of fractional exhaled nitric oxide (FeNO) of sputum eosinophilia in chronic cough (CC) and classic asthma (CA). METHODS: Patients with CC and CA who referred to the Guangzhou Institute of Respiratory Disease were enrolled from 2010 to 2015. The causes of CC was confirmed according to the results of relevant tests and a successful response to the therapy for the initial diagnosis. Sputum induction and FeNO measurement were performed in all patients. Correlations between FeNO and sputum eosinophils in CC and CA were determined by Spearman rank correlation. Receiver operating characteristics (ROC) curve was constructed by using the values of FeNO. RESULTS: A total of 302 patients with chronic cough (CVA, n=95; EB, n=63; UACS, n=24; GERC, n=26 and other causes, n=94) and 163 patients with classic asthma were included in this study. Median FeNO concentration in CC, CA, CA+CVA with sputum eosinophilia was significantly higher than that in CC, CA, CA+CVA without sputum eosinophilia [37.5 (21.0-72.8) ppb vs 16.0 (10.0-22.0) ppb; 55.0 (32.0-92.0) ppb vs 22.0 (15.3-31.5) ppb; 56.0 (34.0-92.0) ppb vs 19.5 (13.3-31.5) ppb, p<0.01 respectively]. Significant positive correlations existed between FeNO and sputum eosiniphils in CC (rs =0.574, p<0.01), CA (rs =0.419, p<0.01), CVA+CA (rs =0.414, p<0.01), respectively. The optimal cut off level of FeNO was 29.5 ppb with sensitivity of 62.0% and specificity of 88.2% for predicting sputum eosinophilia from non-sputum eosinophilia in CC. With the cutoff point of 34.5 ppb, the sensitivity and specificity for differentiating CA with sputum eosinophilia from without sputum eosinophilia were 74.1% and 83.3%. FeNO of 34.5 ppb had a sensitivity and specificity of 74.3% and 79.5% in predicting sputum eosinophilia in asthma (CA+CVA). CONCLUSIONS: There is a significant positive correlation between FeNO and sputum eosinophils both in patients with CC, CA and (CA+CVA). The optimal cut off level of FeNO for predicting sputum eosinophilia in CC is close to that in CA. CLINICAL IMPLICATIONS: FeNO measurement can be used as a helpful tool to predict airway eosinophilic inflammation in chronic cough and asthma to some extent. DISCLOSURE: The following authors have nothing to disclose: Fang Yi, Wei Luo, Ruchong Chen, Siqi Jiang, Xu Zhang, Jiayu Pan, Baojuan Liu, Qiaoli Chen, KeFang Lai No Product/Research Disclosure Information