Association of the Neutrophil-to-Lymphocyte Ratio with Lung Function and Exacerbations in Patients with Chronic Obstructive Pulmonary Disease

BackgroundThe 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.MethodsWe analyzed 885 patients from the Korean COPD Subtype Study cohort that recruited subjects with COPD from 44 referral hospitals. We determined the relationship of NLR levels to severity of lung function using a linear regression model. In addition, we analyzed the experiences of COPD exacerbation according to the NLR quartiles.ResultsNLR levels were inversely associated with severity of airflow limitation as measured by FEV1% predicted and absolute values after adjustments for age, gender, body mass index, pack-years of smoking, and the use of inhaled corticosteroid (P1 significantly improved prediction for exacerbations during 1-year follow-up as measured by the net reclassification improvement (NRI = 7.8%, P = 0.032) and the integrated discrimination improvement (IDI = 0.014, P = 0.021).ConclusionsThe NLR showed a significant inverse relationship to airflow limitation and was a prognostic marker for future exacerbations in patients with COPD.