Meta-analysis of the role of neutrophil to lymphocyte ratio in neonatal sepsis

INTRODUCTION: The neutrophil to lymphocyte ratio (NLR), an inflammatory biomarker, measures innate-adaptive immune system balance. In this systematic review and meta-analysis, we aim to analyze the current literature to evaluate the diagnostic role of NLR in neonatal sepsis. METHODS: PubMed, Web of Science, and Scopus were used to conduct a systematic search for relevant publications published before May 14, 2022. RESULTS: Thirty studies, including 2328 neonates with sepsis and 1800 neonates in the control group, were included in our meta-analysis. The results indicated that NLR is higher in neonates with sepsis compared to healthy controls (SMD = 1.81, 95% CI = 1.14–2.48, P-value < 0.001) in either prospective (SMD = 2.38, 95% CI = 1.40–3.35, P-value < 0.001) or retrospective studies (SMD = 0.87, 95% CI = 0.63–1.12, P-value < 0.001) with a pooled sensitivity of 79% (95% CI = 62–90%), and a pooled specificity of 91% (95% CI = 73–97%). Also, we found that NLR is higher in neonates with sepsis compared to those who were suspected of sepsis but eventually had negative blood cultures (SMD =1.99, 95% CI = 0.76–3.22, P-value = 0.002) with a pooled sensitivity of 0.79% (95% CI = 0.69–0.86%), and a pooled specificity of 73% (95% CI = 54–85%). In addition, neonates with sepsis had elevated levels of NLR compared to other ICU admitted neonates (SMD = 0.73, 95% CI = 0.63–0.84, P < 0.001). The pooled sensitivity was 0.65 (95% CI, 0.55–0.80), and the pooled specificity was 0.80 (95% CI, 0.68–0.88). CONCLUSION: Our findings support NLR as a promising biomarker that can be readily integrated into clinical settings to aid in diagnosing neonatal sepsis. As evidenced by our results, restoring balance to the innate and adaptive immune system may serve as attractive therapeutic targets. Theoretically, a reduction in NLR values could be used to measure therapeutic efficacy, reflecting the restoration of balance within these systems.