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

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).

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.

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.

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.