Association of the neutrophil-to-lymphocyte ratio with lung function and exacerbations in patients with chronic obstructive pulmonary disease

Abstract

<b>Background:</b> The ratio of neutrophils to lymphocytes (NLR) is a widely available marker of inflammation. Several types of inflammatory cells and mediators have been found to be involved in the progression of chronic obstructive pulmonary disease (COPD). We sought to evaluate the association of the NLR with severity of airflow limitation and disease exacerbations in a COPD population. <b>Methods:</b> We analyzed 885 patients from the Korean COPD Subtype Study (KOCOSS) cohort that recruited subjects with COPD from 44 referral hospital. We determined the relationship of NLR levels to a severity of lung function using a linear regression model. In addition, we analyzed the experience of COPD exacerbations according to the NLR quartiles. <b>Results:</b> NLR levels were inversely associated with severity of airflow limitation as measured by FEV₁% predicted and absolute values after adjustments for age, sex, body mass index, and pack–years of smoking (P=0.001 and P=0.003, respectively). As the NLR quartile increased, exacerbations during the past year were more frequent (P trend=0.002). In the multivariate binary regression model, the NLR 4th quartile was found to be a significant predictor of exacerbations during the first year of follow-up. (OR=2.04, 95% CI=1.02 to 4.08; P=0.044). <b>Conclusions:</b> The NLR showed a significant inverse relationship to airflow limitation, and patients with higher NLRs tended more exacerbate during past and future 1year follow up. These results may provide the rationale for the use of NLR as a prognostic marker in patients with COPD.