Reduced COPD Exacerbation Risk Correlates With Improved FEV1: A Meta-Regression Analysis
The 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.METHODS:
By 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.RESULTS:
The 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.CONCLUSIONS:
A significant correlation between increased FEV1 and lower COPD exacerbation risk suggests that airway patency is an important mechanism responsible for this effect.