Internal medicine

BODE index

Lymphocyte

Gastroenterology

Systemic inflammation

COPD

Immunology

Exacerbation

Neutropenia

Inflammation

Neutrophil to lymphocyte ratio

Pulmonary rehabilitation

Acute exacerbation of chronic obstructive pulmonary disease

Copd exacerbation

Toxicity

Medicine

Absolute neutrophil count

International Journal of COPD

Abstract: COPD is characterized by a pulmonary and systemic inflammatory process. Several authors have reported the elevation of multiple inflammatory markers in patients with COPD; however, their use in routine clinical practice has limitations. The neutrophil-to-lymphocyte ratio (NLR) is a useful and cost-effective inflammatory marker derived from routine complete blood count. We performed a systematic literature review using the PRISMA statement. Twenty-two articles were included, recruiting 7,601 COPD patients and 784 healthy controls. Compared with controls, COPD patients had significantly higher NLR values. We found a significant correlation between the NLR and clinical/functional parameters (FEV 1 , mMRC, and BODE index) in COPD patients. Elevation of the NLR is associated with the diagnosis of acute exacerbation of COPD (pooled data propose a cut-off value of 3.34 with a median sensitivity, specificity, and area under the curve of 80%, 86%, and 0.86, respectively). Additionally, increased NLR is also associated with the diagnosis of a bacterial infection in exacerbated patients, with a cut-off value of 7.30, although with a low sensitivity and specificity. The NLR is an independent predictor of in-hospital and late mortality after exacerbation. In conclusion, the NLR could be a useful marker in COPD patients; however, further studies are needed to better identify the clinical value of the NLR. Keywords: acute exacerbations of COPD, bacterial infection, mortality in COPD, inflammatory biomarkers, eosino­philia, GOLD stage

Defining the role of neutrophil-to-lymphocyte ratio in COPD: a systematic literature review