Research On Pulmonary Function And Inflammatory Mediators In Patients With Cough Variant Asthma

Objective: Generally,patients with Classic asthma(CA)have different degrees of small airway dysfunction,and as a special phenotype of asthma,the mechanism and clinical characteristics of Cough variant asthma(CVA)have not been fully defined.This article mainly deals with the difference of small airway function and the relationship with Transforming growth factor beta1(TGF-β1)in Chronic cough(CC),CVA and CA patients,to provide a reference for the diagnosis and treatment of CVA.Methods: This study selected in November 2019-December 2020 in the outpatient service of respiratory department two of the Second Affiliated Hospital of Hebei Medical University.A total of 74 patients with CA,59 patients with CVA,and 34 patients with CC were included.Collection of subjects General data,pulmonary function tests,Bronchial provocation test(BPT)or Bronchodilation test(BDT),Fractional exhaled nitric oxide(FeNO),Immunoglobulin E(Ig E),TGF-β1 were collected.SPSS 24.0statistical software was used for analysis.Pearson correlation coefficient was used for data meeting the normal distribution,and Spearman correlation coefficient was used for data not meeting the normal distribution to analyze the correlation between inflammatory mediators and small airway function.The diagnostic value of inflammatory mediators and MMEF in CVA was analyzed by subject characteristic curve and area under curve.Results: The CA group had the most severe small airway dysfunction,followed by the CVA group,and the CC group had the least small airway dysfunction.The predictive value of FEV1(P=0.00),the predictive value of FEV1/FVC(P=0.01)and MMEF%(P=0.00)in the CVA group were higher than those in the CA group,and there were significant differences between the CVA,CA and CC groups(P=0.00).The airway resistance was higher in the bronchial dilation positive patients than in the bronchial stimulation positive patients.There were significant differences in FeNO values between CA and CVA groups(P=0.01).FeNO values in CVA and CA patients were negatively correlated with pulmonary ventilation function parameters and small airway function parameters(r=-0.551,P=0.00;R =-0.45,P=0.01),there was no significant correlation between FeNO value and small airway function parameters in CC group(r=-0.05,P=0.775).The TGF-β1 was higher in the CA group than in the CVA group(P=0.00),and was negatively correlated with small airway function parameters in both groups(r=-0.358,P=0.02;r=-0.127,P=0.33),TGF-β1 value in CC group had no correlation with small airway function parameters(r=0.053,P=0.758).Airway hyperresponsiveness(AHR)was more significant in the CA group than in the CVA group.According to the characteristic curve(ROC),the cutoff value of FeNO in the CA group was 35.5ppb,with sensitivity 73%,and specificity 69.9%.In the CVA group,the cutoff value of FeNO was 20.5ppb,with sensitivity 91.5%,and specificity 25%.The area under the curve(AUC)showed that in the CA group,the AUC of FeNO,Ig E,TGF-β1 and MMEF were 76.5%,76.8%,80.1% and 22.4%,respectively,and in the CVA group,the AUC of FeNO,Ig E,TGF-β1 and MMEF were 50.6%,42.4%,45.1%,and 60.2%,respectively.Conclusions: Studies have shown that patients with CA have more severe chronic airway inflammation and airway dysfunction than patients with CVA.In addition,most patients in CVA population have small airway disease.CVA and Ca can be distinguished according to the results of FeNO,MMEF and TGF-β1,which can be used for the diagnosis and differential diagnosis of both.