Abstract: Objective To evaluate the role of Astograph methacholine provocation test in diagnosis of bronchial asthma. Methods Totally 56 asthmatics patients were recruited and 90 non-asthmatics patients was enrolled as control. All participants were asked to take Astograph methacholine provocation test. Spirometry and pulse oscillation measurements were conducted, and their breath resistance and spirometry parameters before and after the challenge were recorded and analyzed. Results 1) The provocative test of 52 participants out of 56 asthmatic patients were positive, the positive rate was 92.9%. In the 90 cases of non-asthmatic patients, the provocative test of 42 patients were negative, the negative rate was 46.7%; There was a significant difference in breath resistance at 5Hz(R5), breath resistance at 35 Hz(R35), Peak expiratory flow(PEF), forced expiratory volume in 1 second(FEV₁), forced vital capacity(FVC)(before and after the challenge), accumulated dose minimum induction(Dmin) between asthma group and non-asthmatic group(P<0.05); 2) The sensitivity, specificity, and accuracy of Dmin ≤6 Unit as cutoff for the diagnosis of asthma were 71.2% and 74.4% and 53.0%. The specificity of diagnosis increased significantly when Dmin combined with FEV₁ decreased by 20% as positive standard. Conclusion Astograph methacholine provocation test had good specificity and sensitivity in the diagnosis of bronchial asthma especially when the Dmin≤6 Unit as the cutoff value. Furthermore, its specificity was improved when FEV₁ was measured at the same time.

Key words: asthma, diagnosis, airway hyperreactivity, specificity, sensitivity