RESULTS: A total of 89 patients with chronic cough were enrolled, among which 41 were CVA and 48 were EB. Age, cough duration, comorbidity of allergic rhinitis and sputum differentiation (NEU% and EOS%) were not statistically different between EB and CVA. The gender ratios (female%) and prevalence of nocturnal cough were higher in CVA than EB (75.8% vs 41.7%, 63.2% vs 39.6%, p<0.05 respectively), while the value of FEV1%, FEV1/FVC, MMEF% were lower than those of EB (92.7±11.1 vs 100.0±14.0, 79.2±9.0 vs 83.2±6.5, 62.2±21.8 vs 78.6±21.6, p<0.01 respectively). The efficiency of Bambuterol Hydrochloride was significantly higher than placebo in CVA (64.3% vs 7.7%, p<0.05) and EB (28.1% vs 9.5%, p<0.05). Also, the responsive rate of Bambuterol Hydrochloride in CVA was significantly higher than that of EB (64.3% vs 28.1%, p<0.01). When regarded the responsiveness to bronchodilator as diagnostic criteria of CVA, the sensitivity, specificity, positive predictive value, negative predictive value and positive likelihood ratio were 64.3%, 71.9%, 66.7%, 69.7, 2.3 respectively. The logC5 of bronchodilator responder was significantly higher than non-responder in EB group [2.4 (1.80-3.0) vs 1.54 (0.82-1.87), p<0.05].