Sensitivity and Specificity of the Neutrophil Lymphocyte Ratio (NLR) in Diagnosing Late Onset Neonatal Sepsis in NICU Patients

Objective: To compare the sensitivity and specificity of the neutrophil lymphocyte ratio in diagnosing late onset neonatal sepsis in NICU patients at a tertiary care center Study Design and Setting: Prospective observational study at Department of Pediatrics, Combined Military Hospital, Lahore from February 2024-July 2024 Methodology: After admission into the NICU for suspected late onset neonatal sepsis, complete blood count, C-reactive protein and blood cultures were sent before changing or starting broad spectrum anti-biotic therapy for 350 patients included in the study. Primary variables observed were sensitivity and specificity of the neutrophil lymphocyte ratio in diagnosing late onset sepsis once co-related with the culture results. Results: Blood panel parameters showed mean absolute neutrophil count to be 5928.19796.05/mm3versus 7032.80166.02/mm3 between the suspected and confirmed patients’ groups (p<0.001). Similarly, mean absolute lymphocyte count was 2745.32394.53/mm3 versus 3223.60278.90/mm3 between both groups (p<0.001). Median value for NLR was 1.70 (1.00) versus 2.20 (1.00) between the suspected and confirmed culture groups (p<0.001). Assessment of receiver operating characteristics (ROC) for NLR when compared with suspected and confirmed sepsis showed area under the curve being 0.644 (CI=95%) with sensitivity of 74.6%, specificity of 55.6%, positive predictive value being 57.3% and negative predictive value being 73.3% with a cut-off value for NLR being 2.05. Conclusion: We conclude that neutrophil lymphocyte ratio with a cut-off value of 2.05 is a reliable method to diagnose late onset neonatal sepsis with good sensitivity