Using post-bronchodilator FEV ₁ is better than pre-bronchodilator FEV ₁ in evaluation of COPD severity

Background: The current standards for the diagnosis and treatment of patients with COPD clearly rely on the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria based on post-bronchodilator spirometric values. However, clinical evidence for using the post-bronchodilator FEV ₁ in the severity classification has not been fully investigated. Methods: Patients with COPD were enrolled and followed up prospectively between October 2006 and January 2011. We compared the observed 3-year risk of all causes and respiratory mortality with the risk predicted by the pre- and post-bronchodilator percent predicted FEV1. Other important phenotypes including BMI, MMRC dyspnea scale, ECOG performance status and severe AECOPD (acute exacerbation) were also compared between the two groups. The different severity classifications of COPD, measured according the GOLD guidelines by post- and pre-bronchodilator percent predicted FEV ₁ were compared for prediction of mortality. Results: There were 35 deaths among the 300 COPD patients (11.7%). Multivariate analysis showed that the post-bronchodilator percent predicted FEV ₁ was a significant independent predictor of mortality but pre-bronchodilator percent predicted FEV ₁ was not (p = 0.008 vs 0.126) and it was more strongly correlated with all studied predictors of outcome than the pre-bronchodilator percent predicted FEV1. Kaplan-Meier analysis showed that the discrimination ability to predict mortality from the GOLD criteria using post bronchodilator percent predicted FEV ₁ (p = 0.009) was better than using pre-bronchodilator percent predicted FEV ₁ (p = 0.131). Conclusions: The post-bronchodilator percent predicted FEV ₁ is better than the pre-bronchodilator percent predicted FEV ₁ in the evaluation of the severity of disease in COPD patients and is more accurate in predicting the risk of death by the GOLD classification.