• Alexander D Zider, Xiaoyan Wang, Russell G Buhr, Worawan Sirichana, Igor Z Barjaktarevic, and Christopher B Cooper.
• Division of Pulmonary and Critical Care Medicine, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA.
• Chest. 2017 Sep 1; 152 (3): 494501494-501.

BackgroundThe mechanism by which various classes of medication reduce COPD exacerbation risk remains unknown. We hypothesized a correlation between reduced exacerbation risk and improvement in airway patency as measured according to FEV1.MethodsBy systematic review, COPD trials were identified that reported therapeutic changes in predose FEV1 (dFEV1) and occurrence of moderate to severe exacerbations. Using meta-regression analysis, a model was generated with dFEV1 as the moderator variable and the absolute difference in exacerbation rate (RD), ratio of exacerbation rates (RRs), or hazard ratio (HR) as dependent variables.ResultsThe analysis of RD and RR included 119,227 patients, and the HR analysis included 73,475 patients. For every 100-mL change in predose FEV1, the HR decreased by 21% (95% CI, 17-26; P < .001; R2 = 0.85) and the absolute exacerbation rate decreased by 0.06 per patient per year (95% CI, 0.02-0.11; P = .009; R2 = 0.05), which corresponded to an RR of 0.86 (95% CI, 0.81-0.91; P < .001; R2 = 0.20). The relationship with exacerbation risk remained statistically significant across multiple subgroup analyses.ConclusionsA significant correlation between increased FEV1 and lower COPD exacerbation risk suggests that airway patency is an important mechanism responsible for this effect.Copyright © 2017 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

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