Background: Chronic Obstructive Pulmonary Disease (COPD) is a complex respiratory condition characterized by airflow limitation and systemic inflammation. The COPD Assessment Test (CAT) is an established tool for evaluating the impact of COPD on patient health status. Recent studies have suggested that the Neutrophil Lymphocyte Ratio (NLR) may reflect systemic inflammation and predict exacerbations in COPD.

Objective: To establish the correlation between NLR and CAT scores in COPD patients and to evaluate the potential of NLR as a biomarker for disease severity.

Methods: This cross-sectional observational study included 45 COPD patients. NLR was calculated from complete blood counts, and CAT scores were obtained. Pearson’s correlation coefficient was used to analyze the relationship between NLR and CAT scores.

Results: The mean NLR was 3.5 ± 1.3, and the mean CAT score was 18.2 ± 5.6. A significant positive correlation was found between NLR and CAT scores (r=0.68, p<0.001). Higher NLR values were associated with higher CAT scores, particularly in the highest CAT score category (>20), which had a mean NLR of 4.2 ± 1.1 (p<0.001).

Conclusion: The study provided evidence for a significant positive correlation between NLR and CAT scores, suggesting that NLR could be a valuable biomarker for COPD severity and patient health status impact. These findings reinforce the role of systemic inflammation in COPD and support the potential use of NLR in routine clinical assessment.