The correlation analysis between small airway function and airway hyperresponsiveness

Abstract

Objective To analyse the relationship between small airway function and airway hyperresponsiveness. Methods From October 2012 to May 2013 in Beijing Friendship Hospital and Beijing Fangshan District Liangxiang Hospital, 110 suspected asthma outpatients were selected according to the inclusion criteria and exclusion criteria.Pulmonary ventilation function were employed in bronchial provocation tests (BPT). Compare pulmonary ventilation function and small airway abnormality rate between BPT positive group and negative group.Receiver operating characteristic curve (ROC) was used to evaluate the variations of FEF25/FVC, FEF50/FVC, FEF75/FVC, MMEF/FVC before and after BPT (△FEF25/FVC, △FEF50/FVC, △FEF75/FVC, △MMEF/FVC) diagnostic accuracy, sensitivity and specificity of airway hyperresponsiveness.Correlation analysis between PD20-FEV1 cumulant and △FEF25-75/FVC, △MMEF/FVC on BPT positive group. Results The differences between BPT negative group and positive group were statistically significant in FEV1, FEV1/FVC, FEF25, FEF50, FEF75, MMEF, FEF25/FVC, FEF50/FVC, FEF75/FVC, MMEF/FVC before and after BPT (P<0.05). Both before and after BPT, negative group and positive group showed significant differences in the small airway abnormality rate (χ2=22.482, P=0.000; χ2=25.852, P=0.000). The areas under the curve (AUC) of △FEF25/FVC is 0.792[95%CI(0.703-0.881)](P=0.000), AUC of △FEF50/FVC is 0.767[95%CI(0.677-0.858)](P=0.000), AUC of △MMEF/FVC is 0.667[95%CI(0.563-0.771)](P=0.004). △FEF50/FVC, △MMEF/FVC and PD20-FEV1 are positively correlated with each other (r=0.360, P=0.007; r=0.271, P=0.035). Conclusions Main airways and small airways' functions of patients with airway hyperresponsiveness are significantly lower than patients with normal airway responsiveness.Patients with abnormal small airway function are more likely to have a positive result in BPT.The variations of small airway function before and after BPT can reflect the severity of airway hyperresponsiveness. Key words: Small airway; Airway hyperresponsiveness; Bronchial provocation test