Neutrophil to Lymphocyte Ratio, Monocyte to Lymphocyte Ratio, Platelet to Lymphocyte Ratio as Predictors of Outcome in Children with Lower Respiratory Tract Infection

Abstract

Background: Lower respiratory tract infections (LRTIs) are a leading cause of emergency admissions in pediatric patients. Timely diagnosis and intervention is crucial in reducing the associated morbidity and mortality. This study evaluates the diagnostic and prognostic value of neutrophil to lymphocyte ratio (NLR), monocyte to lymphocyte ratio (MLR), and platelet to lymphocyte ratio (PLR) in pediatric LRTI cases.

Objectives: To determine whether NLR, MLR, and PLR serves as reliable early biomarker for lower respiratory infections and to evaluate their correlation with microbiological findings.

Methods: A Retrospective observational study was conducted in the pediatric in-patient/Out-patient department. A total of 194 episodes from 175 patients with LRTI were compared against 50 control cases. Hematological parameters and sputum cultures were analyzed. Statistical analyses included chi-square, Mann-Whitney U, and ROC curve evaluations.

Results: Significantly elevated NLR, MLR, and PLR values were observed in the study group compared to controls (p<0.001). Pseudomonas aeruginosa and  Haemophilus influenzae were the most frequently isolated pathogens. Elevated ratios correlated with microbiological findings, reinforcing their diagnostic utility.

Conclusion: NLR, MLR, and PLR are effective early markers for LRTI diagnosis and severity assessment. These parameters may guide antibiotic decision-making, particularly when sputum samples are unavailable.