Validity of Platelet to Lymphocyte Ratio and Neutrophil to Lymphocyte Ratio in Diagnosing Early-onset Neonatal Sepsis in Full-term Newborns

Background: This study aimed to evaluate the neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) as diagnostic adjunct tests for early-onset neonatal sepsis (EOS). Methods: This prospective cross-sectional study included 80 full-term neonates with confirmed EOS and 80 healthy newborns. All examinations were done 24 hours after birth. Neonatal sepsis (NS) was characterized as a positive blood culture with symptoms of infection. Positive diagnostic indicators, including I/T ratio > 0.2, total leukocytes [WBCs] of either 5109/L or > 15109/L, thrombocytopenia [150,000/mm3], CRP > 1 mg/dL, and procalcitonin >0.5 ng/mL were considered as NS. Results: As the predictors of EOS, the sensitivity of NLR and PLR was 67% and 70%, and their specificity was 99% and 73%, respectively. Also, positive predictive value (PPV) of NLR and PLR was 98% and 72%, respectively. We found a weak correlation between platelets and sepsis, Strong correlation between WBCs and PLR with sepsis, and a moderate correlation among the ratio of immature to total neutrophil counts (I/T ratio), all of which were significant. Besides, concerning NLR with sepsis, we found an inverse correlation between lymphocytes and sepsis. Conclusions: PLR and NLR are important predictive markers for EOS (PPV of NLR and PLR was 98% and 72%, respectively). Moreover, leukocytosis, thrombocytopenia, high c-reactive protein (CRP), high procalcitonin, and positive blood culture were correlated with the risk of NS. NLR and PLR showed more specificity than CRP and procalcitonin.