P-2159. Pneumonia in Pediatric HSCT Recipients: A Multicentric Prospective Cohort Analysis of Mortality

Abstract Background Infections are common complications in pediatric allogeneic hematopoietic stem cell transplantation (HSCT), with pneumonia often leading to poor outcomes. Data on pediatric patients with pneumonia post-HSCT are limited. This study describes the clinical characteristics and outcomes of affected patients, including those who survived and those who did not. Methods In this prospective cohort study, pediatric patients with pneumonia following HSCT were enrolled between July 2022 and February 2025 across nine HSCT units in Colombia, Mexico, Argentina, and Chile. Cases were identified through active surveillance. Pneumonia was defined as the presence of fever and radiologic infiltrates. The primary outcome was pneumonia-related mortality, as determined by site investigators. Patients were followed until symptom resolution or death. Results 107 patients were included (median age 3.7 years; 57% male), with lymphoblastic leukemia as the most common HSCT indication. Pneumonia developed 83 days post-HSCT (median; IQR 22–237) (Table 1). Bacterial infections predominated, especially within the first 30 days post-transplant (Figure 1a). Pneumonia-related mortality occurred in 28 patients (26%), often between 30 and 100 days post-HSCT (Figure 1b). Mortality was associated with reduced-intensity conditioning (Table 1) and in those presenting with hypotension or hypoxemia (Table 2). Lower death risk was observed in patients presenting with cough or upper respiratory symptoms. Deceased patients were more often neutropenic and lymphopenic, frequently had adenovirus-associated pneumonia and showed certain radiographic features in X-ray, such as central and peripheral infiltrates, as well as diffuse opacities (Table 2). Fifty-three and 44% of patients required intensive care and mechanical ventilation, respectively (Table 3). Conclusion Pneumonia post-HSCT is a major complication in children with a high mortality rate. This well characterized cohort revealed clinical, temporal, etiological, laboratory, and radiologic factors associated with mortality. Continued collaboration is essential to enhance the dataset, identify and validate independent predictors of mortality, and propose effective preventive strategies. Disclosures Almudena Laris Gonzalez, MD, MSc, Astra Zeneca: Advisor/Consultant|GSK: Honoraria|Sanofi: Advisor/Consultant