The Neutrophil to Lymphocyte Ratio Is Related to Disease Severity and Exacerbation in Patients with Chronic Obstructive Pulmonary Disease

Objective Although chronic obstructive pulmonary disease (COPD) is characterized by systemic inflammation, the association between the neutrophil to lymphocyte ratio (NLR; an indicator of inflammation) and the clinical status of COPD has not been well studied. We hypothesized that the NLR is associated with disease severity and exacerbation in COPD patients. Methods We performed blood testing, pulmonary function testing, chest computed tomography, a body composition analysis, and a 6-minute walk test and applied the modified Medical Research Council (MMRC) dyspnea scale for 141 stable COPD patients. In addition, we calculated the body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) index to evaluate the disease severity. Finally, we examined the association between the NLR and clinical parameters in stable COPD patients, and we further investigated changes in the NLR between exacerbation and the stable state. Results The NLR was positively correlated with the BODE index, extent of emphysema, and MMRC score (p<0.001 for all), while inversely correlated with airflow obstruction (p<0.001), body mass index (p<0.001), fat-free mass index (p=0.001), and the 6-minute walk distance (p<0.001). We obtained the NLR during exacerbation from 49 patients. The NLR was significantly higher at exacerbation compared to the stable state (p<0.001). Conclusion The NLR was associated with disease severity and exacerbation in COPD patients. Therefore, the usefulness of the NLR in COPD patients should be elucidated in clinical settings in future investigations.