Abstract Rationale Lung injury following hematopoietic stem cell transplantation (HSCT) is a major clinical challenge in the pediatric population, contributing significantly to post-transplant morbidity and mortality. While prior studies using pulmonary function tests (PFTs) have assessed the risk of developing post-HSCT lung disease, none have evaluated the timing of injury. Qualitative scoring of computed tomography (CT) imaging can detect early or subclinical changes and may serve as a predictor for post-transplant pulmonary complications. As part of the TRANSPIRE study, we aimed to determine whether baseline CT abnormalities predict earlier onset of post-HSCT lung-related events. Methods Pediatric and young adult patients undergoing HSCT were enrolled in the TRANSPIRE study and performed spirometry as well as chest CT prior to transplant if baseline PFTs were abnormal. A CT scan was considered abnormal if ≥ 1 clinically significant finding was present: infection, interstitial changes, ground-glass opacities, air trapping, linear opacities, mosaicism, post-transplant lymphoproliferative disorder or malignancy, pleural or cardiac effusion, or pulmonary nodules. Percent predicted forced expiratory volume in one second (ppFEV1), forced vital capacity (ppFVC), and ppFEV1/FVC were derived from spirometry. Lung-events were defined by TRANSPIRE criteria, and risk was quantified using Kaplan-Meier plots, hazard ratios, and intergroup differences by Mann-Whitney U tests. Results CT was obtained in 291 patients across 8 sites (male:female=107:184, median IQR age= 9.6 5.0, 15.5 years) prior to HSCT; 110 (38%) of patients showed an abnormal CT finding. A Kaplan-Meier curve showed a higher risk of lung-related events in patients with abnormal CT findings (Hazard Raio=1.54, p = 0.017) (Figure 1). Within one-year post-transplant, lung-related events occurred in 56 (51%) and 75 (41%) patients with abnormal and normal CTs, respectively. The most common event was detection of a new pulmonary pathogen (44% vs. 41% for abnormal and normal CT, respectively). Patients with abnormal versus normal CTs showed no significant differences in age at transplant (p = 0.607), sex (p = 0.697), or indication for HSCT (p = 0.141), with malignancy being the most common diagnosis in both groups. Pre-HSCT ppFEV1 and ppFVC were slightly lower in those with abnormal CTs (ppFEV1: 94% vs. 99%, p = 0.013; ppFVC: 97% vs. 103%, p = 0.014), while FEV1/FVC did not differ (p = 0.399). Conclusion Pediatric HSCT recipients with abnormal baseline CT findings experienced lung-related events earlier and more frequently within the first-year post-transplant, independent of transplant indication. These findings suggest that structural abnormalities identified on pre-HSCT CT may serve as an early imaging biomarker of future pulmonary complications, complementing standard functional assessment from PFTs. This abstract is funded by: R01HL157392
Munidasa et al. (Fri,) studied this question.