Evaluation of the utilization Neutrophil-Lymphocyte Ratio (NLR) and Immature-to-Total Neutrophil (I/T) Ratio in diagnosing Late-Onset Neonatal Sepsis (LONS) in 31-36 weeks preterm neonates in Indonesia

Background: Late-onset neonatal sepsis (LONS) is a leading cause of death and morbidity among preterm neonates. Early diagnosis is crucial for appropriate and prompt management. A rapid, simple, and readily accessible diagnostic tool is important to diagnose LONS early. This study aims to assess the diagnostic value of the neutrophil-lymphocyte ratio (NLR) and NLR combined with the immature-to-total (I/T) ratio for diagnosing LONS. Methods: This retrospective cross-sectional study collected data from Cipto Mangunkusumo Hospital Neonatology Division medical records from January 2018 to December 2019. Preterm neonates with 31-36 weeks of gestational age, 7-28 days of postnatal age, and clinical sepsis were eligible for this study. Enrolled neonates were classified into two groups, proven sepsis, and unproven sepsis. The NLR and I/T were taken from the medical records. Results: From 126 subjects, 70 were proven sepsis, and 56 were unproven. Receiver operating curve analysis for NLR was calculated, and the area under the curve of NLR corresponded to 0.953. The NLR cut-off point with the highest specificity and positive predictive value (PPV) was 1.785 (78.57% sensitivity, 92.86% specificity, 93.22% PPV, and 77.61% negative predictive value). Using a cut-off point of > 0.2, the I/T ratio has 55.70% sensitivity, 83.70% specificity, 81.25% PPV, and 60.26% NPV. The NLR and I/T ratio increased the sensitivity and PPV of the I/T ratio to 90% and 84.44%, respectively. Conclusion: The NLR with cut-off point 1.785 has good diagnostic value for LONS in 31-36 weeks preterm neonates. A combination of NLR and the I/T ratio can increase the diagnostic value of the I/T ratio.