Neutrophil-to-Lymphocyte Ratio as a Prognostic Marker in Chronic Obstructive Pulmonary Disease: Assessing Exacerbations, Mortality, and Systemic Inflammation

Lionel John J ¹, Srinivasan N ¹, Shiva P ^1*, Radhakrishnan P ¹

The NLR is a promising, cost-effective marker for predicting COPD exacerbations and mortality, with potential for routine clinical use.

Abstract

Background: Chronic Obstructive Pulmonary Disease (COPD) is a progressive condition characterized by inflammation and destruction of pulmonary tissue, leading to chronic airflow limitation. In addition to pulmonary complications, COPD is frequently associated with systemic inflammation and various comorbidities, which contribute to increased morbidity and mortality. The neutrophil-to-lymphocyte ratio (NLR) has emerged as a potential marker of systemic inflammation and disease severity in COPD. Methods: This review synthesizes findings from studies evaluating NLR in COPD patients, including those with stable disease, acute exacerbations (AECOPD), and various comorbid conditions. We examined studies that investigated the role of NLR in predicting disease severity, exacerbation risk, and mortality, and explored its relationship with traditional inflammatory markers and comorbidities. Results: NLR values are significantly higher in COPD patients compared to healthy controls and show strong correlations with other inflammatory markers such as C-reactive protein (CRP) and red cell distribution width (RDW). Elevated NLR is associated with increased risk of AECOPD, bacterial infections, and mortality. Specific NLR cut-off values have been identified for different clinical scenarios, with higher values indicating greater disease severity and worse outcomes. Studies also highlight the influence of comorbid conditions, such as metabolic syndrome and cancer, on NLR levels. Conclusion: NLR is a simple, cost-effective marker with potential utility in assessing disease severity, exacerbation risk, and prognosis in COPD patients. Its correlations with traditional inflammatory markers and varying cut-off values across clinical contexts support its role as a valuable tool in managing COPD. Further large-scale, prospective studies are needed to validate its clinical applications and establish standardized NLR thresholds for routine practice.

Keywords: Neutrophil-to-Lymphocyte Ratio, Chronic Obstructive Pulmonary Disease, Acute Exacerbations, Systemic Inflammation, Prognostic Marker

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