The Neutrophil-to-Lymphocyte Ratio as a Prognostic Marker for Disease Severity in Hospitalized Patients with Community-Acquired Pneumonia

Abstract

Background: Community-acquired pneumonia (CAP) remains a major cause of hospitalization and mortality worldwide. Early identification of patients at risk of severe disease and poor outcomes is essential for appropriate triage and management. The neutrophil-to-lymphocyte ratio (NLR), derived from routine complete blood counts, has emerged as a potential prognostic biomarker in infectious diseases, including CAP. Objective: To evaluate the prognostic utility of the admission Neutrophil-to-Lymphocyte Ratio (NLR) for predicting disease severity and clinical outcomes in hospitalized patients with Community-Acquired Pneumonia (CAP). Methodology: This observational, prospective study was conducted at the Department of Medicine, Saidu Sharif Teaching Hospital, Swat, from January 2023 to April 2024. The research team enrolled a total of 150 adult patients through consecutive sampling who were hospitalized with community-acquired pneumonia radiologically confirmed by X-ray or CT-scan. Data on patients' demographics, clinical findings, laboratory parameters, and X-ray features were collected at admission. The severity of the disease was measured by the CURB-65 scoring system. The admission NLR was calculated by the absolute neutrophil and lymphocyte counts. Patients were followed up for outcomes like admission to the intensive care unit (ICU), requirement for mechanical ventilation, and in-hospital death. Results: The mean age of patients was 56.2 ± 15.7 years, with male predominance (57.3%). Severe CAP (CURB-65 ?3) was observed in 26.7% of patients. The mean NLR was significantly higher in patients with severe disease than in those with mild to moderate CAP (14.6 ± 6.1 vs. 7.9 ± 4.3; p < 0.001). Elevated NLR was strongly associated with ICU admission, mechanical ventilation, and mortality. A significant positive correlation was observed between NLR and CURB-65 score (r = 0.69, p < 0.001). Conclusion: An elevated admission NLR is a strong predictor of disease severity and adverse clinical outcomes in hospitalized patients with community-acquired pneumonia. NLR may serve as a useful adjunct to established severity scoring systems for early risk stratification.