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

## TL;DR

This study examines pneumonia in children after stem cell transplants, finding it is a serious condition with a high death rate.

## Contribution

The study provides new clinical insights into pneumonia in pediatric HSCT recipients and identifies factors linked to mortality.

## Key findings

- Pneumonia-related mortality occurred in 26% of patients, often between 30 and 100 days post-HSCT.
- Bacterial infections were most common early after transplant, while adenovirus was linked to deaths.
- Radiographic features like central and peripheral infiltrates were associated with higher mortality.

## Abstract

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.

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.

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).

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.

Almudena Laris Gonzalez, MD, MSc, Astra Zeneca: Advisor/Consultant|GSK: Honoraria|Sanofi: Advisor/Consultant