Objective:To investigate the differentiation of airway inflammation, bronchial hyperresponsiveness and anti-asthma therapy responses between the Cough variant asthma (CVA) and classic asthma (CA) patients with FEV₁%?80% predicted. 

Methods:402 patients of suspected CA and 544 patients of chronic cough with FEV1 ?80% predicted were enrolled in the first monocentre retrospective cross-sectional study. Further prospective monocentre study was conducted and 66 patients of suspected asthma with negative bronchodilation test (BDT) but positive bronchial challenge test (BCT) were enrolled and followed up for 4 weeks. 

Results:Both CA and CVA patients showed decreased FEV₁%, MEF50%, MEF25%, and MMEF% values; increased EOS% and FENO values. CA patients had higher FENO values than CVA patients (36.0ppb vs. 24.0ppb, p<0.0001). The predictive value of FENO for positive BCT in chronic cough patients was much lower than that in suspected CA patients (AUC=0.603 vs. 0.728). After anti-asthma therapy of 4 weeks, dramatically improvement of symptoms, large and small airway function were found both in CVA and CA groups with no difference between groups. The 2 most valuable spirometric variables for predicting better anti-asthma response were ?FEV₁ (cut-off values=90ml for CA and 110ml for CVA) and ?FEV₁% (cut-off values=3.49% for CA and 2.59% for CVA) in CA and CVA patients respectively.

Conclusion:CVA patients showed less airway eosinophilic inflammation than CA patients. Most CA and CVA patients can benefit promptly from anti-asthma therapy,the improvement of FEV₁ and FEV₁% in BDT may predict anti-asthma therapy response.