The role of fractional exhaled nitric oxide,eosinophil in peripheral blood and the IgE in the diagnosis of eosinophilic asthma

BAI Xue; QIN Guangmei; HU Hong; HAN Guojing; MAO Dan

doi:10.3969/j.issn.1671-6450.2017.09.007

Abstract：Objective To research the role of fractional exhaled nitric oxide(FeNO), eosinophil in peripheral blood and the serum IgE in the diagnosis of eosinophilic asthma and analyze the value of the biomarkers as direct diagnostic reference of eosinophilic asthma.Methods One hundred and seven patients with asthma and thirty normal persons were enrolled.The patients with asthma were divided into two groups: the group of eosinophilic asthma(the percent of eosinophil in induced sputum was greater than or equal to 3%);the group of non-eosinophilic asthma(the percent of eosinophil in induced sputum was less than 3%).The difference of FeNO, eosinophil in peripheral blood and the serum IgE between the three groups and explore the relationship between FeNO, eosinophil in peripheral blood, the IgE in serum and eosinophil in induced sputum were compared.The percent of eosinophil in induced sputum was used as gold criteria of diagnosis of eosinophilic asthma, the role of FeNO, eosinophil in peripheral blood and the serum IgE in the diagnosis of eosinophilic asthma were analyzed and the diagnostic efficiency were compared.Results In eosinophilic asthma group,the level of FeNO,the concentration of IgE, the percent of eosinophil in peripheral blood were higher than those in group of non-eosinophilic asthma (q =35.4, P <0.01;q =5.6, P <0.05;q =5.3, P =0.000);those in group of non-eosinophilic asthma were higher than that in group of normal persons (q =15.0, P =0.000;q =51.0, P =0.000;q =19.8, P =0.000).The level of FeNO has positively correlated to the percent of eosinophil in induced sputum (r =0.313, P =0.001);the percent of eosinophil in peripheral blood also has the positive correlation with the percent of eosinophil in induced sputum (r =0.597, P =0.000);no significant correlation was observed between the concentration of IgE and the percent of eosinophil in induced sputum (r =0.083, P =0.083).In the external validation cohort,AUC for FeNO level was 73.3% (95% CI 0.607-0.860, P =0.002) to detect eosinophilic asthma.When the level of FeNO was 43 ppb, the sensitivity was 62.5%, the specificity was 75.0% and the maximum Yonden Index was 0.375.AUC for eosinophil in peripheral blood was 78.4% (95%CI 0.667-0.901, P =0.000) to detect eosinophilic asthma.When the percent of eosinophil in peripheral blood was 4.5%, the sensitivity was 83.3%, the specificity was 80.5% and the maximum Yonden Index was 0.538.AUC for IgE level was 67.9% (95% CI 0.546-0.812, P =0.015) to detect eosinophilic asthma.When the level of serum IgE was 34.5IU/ml,the sensitivity was 79.5%,the specificity was 50.8%,the maximum Yonden index was 0.303.Conclusion The level of FeNO and the percent of eosinophil in peripheral blood have the positive correlation with the percent of eosinophil in induced sputum;FeNO and the eosinophil in peripheral blood can help diagnosis eosinophilic asthma;the diagnostic efficiency of eosinophil in peripheral blood is better than that of FeNO but the optimum cutoff point need to be further studied.