Association of Neutrophil-to-Lymphocyte Ratio with Etiology and Severity of Acute Exacerbation of COPD

Background: Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) refer to an abrupt deterioration in airway function and respiratory symptoms among individuals with COPD. The neutrophil-to-lymphocyte ratio (NLR) is a simple, cost-effective biomarker of systemic inflammation. Early diagnosis and clinical assessment may be enhanced by assessing the relationship between NLR and the aetiology and severity of AECOPD. Objective: To assess the association of the neutrophil-to-lymphocyte ratio (NLR) with the aetiology and severity of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). Methods: This cross-sectional observational study enrolled 180 patients with AECOPD through convenience sampling at the Department of Medicine, North East Medical College Hospital, Sylhet, over an eight-month period. Clinical information was recorded, and venous blood samples were collected for complete blood count, differential leucocyte count and C-reactive protein assessment. Patients were classified as having infectious exacerbations based on the study's specified inflammatory laboratory criteria. Associations were evaluated using the Mann–Whitney U test, receiver operating characteristic analysis and univariate logistic regression. Results: Of 180 patients, 126 (70%) were classified as having infectious exacerbations and 54 (30%) as having non-infectious exacerbations. The overall mean NLR was 6.78 ± 4.52. Mean NLR was higher in the infectious than the non-infectious group (5.96 versus 4.59; p = 0.014). An NLR cut-off of 5.12 distinguished severe or very severe exacerbations with 70.7% sensitivity, 73.0% specificity and an area under the curve of 0.772. NLR was associated with exacerbation severity in univariate regression (OR 1.347; 95% CI 1.171–1.550). Conclusion: NLR was associated with presumed infectious aetiology and exacerbation severity in this hospital-based cohort and may have value as an adjunct to clinical assessment.