ABSTRACT
Objective:To evaluate the application of fractional exhaled nitric oxide (FeNO) and peripheral blood eosinophil (EOS) count in the diagnosis of eosinophilic asthma.Methods:The clinical data of 89 patients newly diagnosed as asthma in Department of Respiratory and Critical Medicine of the First Hospital of Shanxi Medical University from May 2016 to March 2018 were retrospectively analyzed. Pulmonary function, FeNO, induced sputum cytology classification and peripheral blood cell analysis were performed. The EOS% in induced sputum ≥3% was used as criteria for diagnosis of eosinophilic asthma (eosinophilic asthma group, n=34), and the other 55 patients were included in non-eosinophilic asthma group. The pulmonary function of the two groups were compared. The correlations among FeNO, EOS% in induced sputum and peripheral blood EOS count were analyzed. The diagnostic efficiency and optimal thresholds points of FeNO and peripheral blood EOS count to diagnose eosinophilic asthma were assessed by ROC curves. Results:The forced expiratory volume in one second (FEV 1)/pre(%) was (90.3±26.1)% and FEV 1/ forced vital capacity (FVC) was (69.1±11.8)% of the eosinophilic asthma group, which were significantly lower than those of the non-eosinophilic asthma group [(110.1±20.3)%, t=4.014, P<0.01 and (80.1±6.0)%, t=5.003, P<0.01]. FeNO was positively correlated with the EOS% in induced sputum ( r=0.670, P<0.01), peripheral blood EOS count was positively correlated with EOS% in induced sputum ( r=0.741, P<0.01), peripheral blood EOS count was positively correlated with FeNO ( r=0.647, P<0.01). The optimal cut-off of FeNO value was 65 ppb (AUC=0.887, P<0.01) and the sensitivity was 0.647, the specificity was 1.000. The optimal cut-off of peripheral blood EOS count was 0.225×10 9/L (AUC=0.898, P<0.01), the sensitivity and specificity were 0.794 and 0.891, respectively. The combination of FeNO and peripheral blood EOS count had better diagnostic value (AUC=0.916, P<0.01) with a sensitivity of 0.794 and a specificity of 0.945. Conclusion:FeNO and peripheral blood EOS count are reliable indicators for the diagnosis of eosinophilic asthma, and the combination of the two indicators can more effectively predict the presence of eosinophilic airway inflammation in patients with asthma.