Neutrophil-to-lymphocyte ratio: A disease severity biomarker in stable chronic obstructive pulmonary disease?

Abstract

The neutrophil-to-lymphocyte ratio (NLR) is a biomarker of systemic inflammation that has been investigated in different chronic diseases. However, its role as biomarker of severity in patients with stable chronic obstructive pulmonary disease (COPD), and particularly its association with cardiovascular risk, remains unclear. This retrospective study aimed to evaluate whether a higher NLR (HNLR) is associated with worse disease control and increased cardiovascular risk compared to a lower NLR (LNLR) in stable COPD. Data from inpatients admitted to a pulmonary rehabilitation center between 2021 and 2024 were analyzed. Patients were divided in two groups (HNLR ≥ 2.26 and LNLR < 2.26) based on the NLR threshold best associated with severe exacerbations according to ROC analysis. Comparison between groups and multivariate logistic regression analysis were performed. Cardiovascular risk was assessed using the European Society of Cardiology-recommended algorithm. A total of 247 patients were included. The HNLR group included a significantly (p < 0.05) higher number of patients with severe exacerbations in the previous year, lower forced expiratory volume in 1 second, higher residual volume, and increased partial pressure of carbon dioxide in arterial blood than the LNLR group. Chronic respiratory failure, atrial fibrillation and lung cancer were significantly more frequent in the HNLR group, and these patients had a significantly higher 10-year cardiovascular risk. Our data suggest that NLR used together with other clinical and functional parameters could represent a useful biomarker in stable COPD, associated with increased disease severity and higher estimated 10-year cardiovascular risk.