Association between blood culture positivity and in-hospital mortality in pediatric oncology patients with sepsis in the PICU: a retrospective cohort analysis.

Background: Sepsis is one of the major causes of death in pediatric oncology patients. However, whether blood culture positivity is independently associated with mortality in this high-risk, immunocompromised population remains unclear. We evaluated whether blood culture results are associated with survival outcomes in pediatric oncology patients with sepsis treated in the pediatric intensive care unit (PICU). Methods: We retrospectively identified sepsis episodes among pediatric oncology patients admitted to the PICU between 2016 and 2024 according to the Phoenix Sepsis Criteria. Clinical variables were compared by blood culture status and in-hospital survival. We used generalized estimating equation (GEE) logistic regression models that accounted for clustering of sepsis episodes within patients to assess the association between blood culture positivity and in-hospital mortality. Results: The primary analysis included 234 sepsis episodes contributed by 209 patients; all episodes met the Phoenix pediatric sepsis criteria. Blood cultures were positive in 48 episodes (20.5%), and in-hospital death occurred in 45 episodes (19.2%). The blood culture-positive group had higher procalcitonin (PCT) levels (p = 0.015), whereas no statistically significant differences were observed in Phoenix Sepsis Score, organ function indicators, invasive mechanical ventilation (IMV) or continuous renal replacement therapy (CRRT) requirements, PICU length of stay, or in-hospital mortality. In GEE models accounting for within-patient clustering, blood culture positivity was not independently associated with in-hospital mortality (OR = 1.412, 95% CI 0.536-3.719, p = 0.485). In contrast, higher lactate and vasoactive-inotropic score (VIS) were independently associated with increased mortality, whereas higher PaO Conclusion: In this single-center retrospective cohort of sepsis episodes among pediatric oncology patients, blood culture positivity was not independently associated with in-hospital mortality after adjustment for age, organ dysfunction markers, and prior antimicrobial exposure. In contrast, several markers of organ dysfunction remained independently associated with mortality. However, given the limited number of deaths and the potential for culture-status misclassification related to prior antimicrobial exposure, a clinically meaningful association between blood culture positivity and mortality cannot be excluded.