The Diagnostic Value Of Small Airway Index In Redifferentiating Chronic Obstructive Pulmonary Disease And Asthma-COPD Overlap

BackgroundIn epidemiological studies,the prevalence of Asthma-chronic obstructive pulmonary disease overlap(ACO)in different gender and age reports is between 9%and 55%.This wide range of prevalence reflects the different diagnostic criteria used by different research investigators.Among people with chronic obstructive pulmonary disease(COPD)or asthma,15%to 32%are diagnosed with COPD and asthma at the same time.Compared with patients with simple asthma or COPD,patients with both asthma and COPD characteristics experience more frequent acute exacerbations,poor quality of life,faster decline in lung function,higher mortality,and more social medical burden.Although few studies have analyzed the benefits of identifying ACO patients in COPD patients,it is important to identify ACO in COPD patients because ACO responds well to inhaled corticosteroid(ICS).Studies have shown that in patients with chronic obstructive pulmonary disease or bronchial asthma,small airway resistance increases,while in patients with asthma-chronic obstructive pulmonary disease overlap,patients have both characteristics,and may have higher small airway resistance,so it is inferred that small airways The indicators may have certain clinical value in identifying patients with ACO.ObjectiveIn this study,we evaluated the small airway resistance indicators of patients with simple COPD and ACO,and explored the diagnostic value of small airway resistance in patients with simple COPD and ACO,so as to provide a basis for the characteristics and diagnosis of ACO.MethodsContinuously include patients who met the inclusion and exclusion criteria from October 2017 to January 2019 to the outpatient clinic of Zhujiang Hospital of Southern Medical University.The demographic characteristics of all patients were collected,and the subjects were treated by a full-time staff in the same pulmonary function room.Perform IOS and spirometry tests,refer to the 2017 Global Initiative for Chronic Obstructive Lung Disease(GOLD)diagnostic criteria for COPD and the 2017 Spanish guidelines for management of chronic obstructive pulmonary disease(Spanish guidelines for management of chronic obstructive pulmonary disease,GesEPOC).The diagnostic criteria of ACO in obstructive pulmonary disease(GesEPOC)divide patients into simple COPD group and ACO group.The small airway resistance indexes of the two groups of patients were compared,and the receiver operating characteristic(ROC)curve analysis was used to determine the value of pulmonary ventilation function and impulse pulmonary function parameters in distinguishing ACO from COPD.Results:1.Compared with simple COPD patients,ACO patients have lower spirometer indicators,FEV1(1.33vs 1.72;p=0.055),FEV1(%predicted)(57.5vs68.6 p=0.004),MMEF%19.55vs26.30.2.Compared with simple COPD patients,ACO patients’ Z5,R5,R20,R5-R20 and X5 levels were significantly higher(P<0.001).In the ACO group,FEV1%(54.49s70.91 p=0.018*)and FVC1%(78.47vs93.06 p=0.026*)were higher in the female group;while Z5(kPa/L/s)(0.63vs0.8±0.23 p=0.008*),R5(kPa/L/s)(0.56vs0.73 p=0.003*)R20(kPa/L/s)(0.34vs0.50 p<0.0001),R5-R20(0.19vs0.13 p=0.039)is higher than that of males.3.Each measurement index of MMEF and IOS has certain diagnostic value for ACO patients.Among them,R5-R20 and X5 have medium diagnostic.value,R5-R20 and high diagnostic value(AUC=0.737),and the best cut-off value is 0.14 kPa/L/s,the corresponding sensitivity is 75.0%,the specificity is 56.4%,the positive predictive value is 41.4%,and the negative predictive value is 86.6%.Conclusion1.Compared with simple COPD patients,ACO patients are younger and have worse lung function.2.IOS-related indicators increased in both COPD and ACO patients,and ACO increased more significantly than COPD(P<0.05);female airway resistance in the ACO group was higher than that of males.3.IOS small airway indicators R5,R5-R20,X5 have moderate diagnostic value for the diagnosis of ACO patients,R5-R20 has a higher diagnostic value(AUC=0.737),the best cut-off value is 0.14 kPa/L/s,The negative prediction The value is 86.6%.