P1.219: Assessment of the RDW-to-Platelet Count Ratio as an Indicator of Neonatal Sepsis in Premature Newborns

Background: Neonatal sepsis remains a major contributor to preterm infant mortality and morbidity both globally and in the United States. The current gold standard for diagnosing neonatal sepsis relies on microbial cultures; however, recent large-scale randomized controlled trials indicate that up to 46% of cases may be culture-negative. A complete sepsis evaluation typically requires 48–72 hours of negative blood cultures to rule out infection. Due to the lack of a universally accepted definition of neonatal sepsis, diagnosis is often based on a combination of clinical symptoms and laboratory markers, which can be nonspecific and highly variable. An increase in red blood cell distribution width (RDW) and a decrease in platelet count are well-documented inflammatory responses. This study aimed to evaluate the RDW-to-platelet count ratio (RP ratio) as a potential biomarker for both early-onset and late-onset sepsis in premature newborns.

Methods: A retrospective case-control study was conducted on a cohort of premature newborns born over a ten-year period. The sepsis group included infants born before 36 6/7 weeks of gestation who met the criteria for early- or late-onset sepsis, while premature newborns without sepsis served as controls. RDW and platelet counts were collected to assess the association between sepsis and the RP ratio. Statistical analyses included the Mann-Whitney U test for comparing non-normally distributed continuous variables and the chi-square test for categorical variables. Logistic regression analysis was performed to evaluate the association between the RP ratio and neonatal sepsis while adjusting for potential confounders.

Results: A total of 292 subjects were included in the study - 52 with neonatal sepsis and 240 controls. Table 1 summarizes the characteristics of the study population. The sepsis and control groups differed significantly in terms of gestational age, birthweight (p < 0.001), and antenatal steroid therapy (p = 0.03), among other variables. These factors were identified as potential confounders associated with sepsis cases. Table 2 presents the differences in RP ratios between cases and controls. The RP ratio was significantly higher in premature newborns diagnosed with sepsis (p < 0.004). However, subgroup analysis of early- and late-onset sepsis in preterm infants showed no statistically significant difference between these two groups (p = 0.9). Multivariate logistic regression analysis, adjusting for confounding factors, demonstrated that the RP ratio was independently associated with neonatal sepsis (p < 0.006).

Conclusion: The RP ratio was significantly higher in septic neonates and independently associated with sepsis, showing potential as a biomarker for neonatal sepsis. Further studies with larger, more diverse populations are needed to validate these results.