The value of Astograph provocation test and small airway function index in the diagnosis of asthma / 中国医师杂志

ABSTRACT

Objective:To explore the value of Astograph challenge test and small airway functional parameters to diagnose asthma.Methods:86 asthmatics were enrolled along with 40 non-asthmatic patients as a control group from January 2018 to March 2019 in People′s Hospital of Nanhai Economic Development Zone, Foshan Chancheng District Central Hospital and Affiliated Hospital of Guangdong Medical University. All subjects were required to complete data acquisition, impulse oscillometry (IOS), pulmonary function test, and Astograph challenge test. The routine pulmonary function indexes, pulse oscillation indexes and reaction threshold (Dmin) were compared between asthma group and non asthma group, and the correlation between each index was analyzed.Results:The Dmin, max expiratory at 50% forced vital capacity (MEF 50%), max expiratory at 75% forced vital capacity (MEF 25%), maximal mid expiratory flow (MMEF) of asthma group were significantly lower than those of non-asthmatic group ( P<0.05). The IOS parameters such as respiratory impedance (Zrs), resistance at 5 Hz (R 5), resistance at 20 Hz (R 20), peripheral resistance (R 5-R 20), reactance at 5 Hz (X 5), the resonance frequency (Fres) showed no statistical significance between the asthmatics and the non-asthmatics ( P>0.05). Response threshold (Dmin) was positively correlated to MEF 50, MEF 25 and MMEF respectively (0.295, 0.306, 0.381, all P<0.05). A receiver operating characteristic (ROC) analysis indicated the area under ROC curve (AUC) of Dmin in diagnosis of asthma was 0.978 (95% CI 0.950-1.000), the best cutoff point of Dmin was 13.609 Units, with sensitivity in diagnosing asthma 94.6%, specifity 96.8%. The AUC for MEF 50, MEF 25, MMEF were 0.674, 0.738, 0.683, with the best cutoffs 3.990 L, 1.685 L, 3.445 L, respectively. Conclusions:Astograph challenge test, which is fast, safe and precise, can assist in the diagnosis of asthma. MEF 50 and MEF 25 may be associated with the diagnosis of asthma and can predict airway hyper-responsiveness while IOS parameters could not, which make MMEF, MEF 50 and MEF 25 superior to IOS parameters in the diagnosis of asthma.