The role of FEV₁/FVC in the prediction of acute exacerbation of COPD

Background: Whether the ratio of forced expiratory volume in 1 s to forced vital capacity (FEV₁/FVC) can be used as a biomarker to predict the risk of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is unclear.

Methods: To investigate the predictive role of FEV₁/FVC for AECOPD, we analyzed data from an observational and multicenter cohort study of 2043 patients with COPD in KOREA. Exposures were post-bronchodilator FEV₁/FVC and/or percentage predicted FEV₁ (FEV₁%pred). The outcome was the development of AECOPD during the first year of follow-up.

Results: During the first year of follow-up, the proportion of patients who developed AECOPD increased as FEV₁/FVC decreased (P < 0.01). FEV₁/FVC and FEV₁%pred had similar predictive power for AECOPD, with optimal predictive cut-offs of approximately 0.5 for FEV₁/FVC and 50 % for FEV₁%pred. When the participants were classified into groups based on these cut-offs, compared with a high both-lung function group (FEV₁/FVC≥0.5 and FEV₁%pred≥50 %), the low-FEV₁ group (FEV₁/FVC≥0.5 and FEV₁%pred<50) had a modestly increased risk of severe AECOPD (adjusted odds ratio[aOR] = 3.12; 95 % confidence interval[CI] = 1.59-6.16), while the risk of severe AECOPD was the highest in the low both-lung function group (FEV₁%pred<50 % and FEV₁/FVC<0.5) (aOR = 5.16; 95 % CI = 3.34-7.97).

Conclusions: FEV₁/FVC is a spirometric biomarker predictive of AECOPD. In countries where FEV₁%pred is not available for their population, FEV₁/FVC could be used as a biomarker for assessing the risk of AECOPD. In countries where accurate FEV₁%pred is available, both FEV₁%pred and FEV₁/FVC could be used to provide additional information to assess the risk of AECOPD.

Key message: This study showed that FEV₁/FVC had similar predictive power for AECOPD compared with percentage predicted FEV₁. Furthermore, the use of both FEV₁ and FEV₁/FVC provides additional information for the risk assessment of AECOPD.