Risk Factors for Bronchiolitis Obliterans Syndrome in Pediatric Lung Transplant Recipients

Abstract

<h3>Purpose</h3> The purpose of this study is to describe the survival of pediatric patients who develop bronchiolitis obliterans syndrome (BOS) after lung transplant (LTx) and to identify the risk factors leading to the diagnosis. <h3>Methods</h3> The UNOS Registry was queried to identify pediatric LTx recipients (age <18yo) from 1999 to 2019. Kaplan-Meier analysis was used to identify median time to BOS diagnosis. Cox-regression analysis was used to identify potential risk factors leading to diagnosis. <h3>Results</h3> 900 lung transplant recipients were identified. 48% (n=431) of these patients were diagnosed with BOS in the post-transplant period. These patients developed BOS after a median of 4.6 years (95% CI: 4.3-5.0). Compared to non-BOS patients, those who developed BOS were less often infants (9% vs. 15%, p=0.008), more frequently aged 2-11yrs (28% vs. 22%, p=0.049), less frequently ventilator dependent at time of LTx (14% vs. 22%, p=0.001), and more frequently experienced graft rejection within 1-yr post-LTx (38% vs. 23%, p<0.001). Multivariate analysis revealed ages 12-17yrs (HR 1.3, CI 1.0-1.6), donor-recipient weight ratio <0.8 (HR 1.6, CI 1.2-2.2), OB (non-retransplant) diagnosis (HR 1.9, CI 1.3-2.9), and graft rejection within 1-yr post-LTx (HR 1.9, CI 1.6-2.4) to be significant predictors of developing BOS. Within those who developed BOS, ages 12-17yrs (HR 2.0, CI 1.1-3.6) and graft rejection within 1-yr post-LTx (HR 1.5, CI 1.2-2.0) were found to be significant predictors of mortality. On Kaplan-Meier analysis, early BOS (within 3-yrs post-LTx) had significantly lower graft survival from the diagnosis of BOS compared to those who developed BOS later (after 3yrs). (<b>Figure</b>, p<0.001). <h3>Conclusion</h3> BOS remains a significant cause of mortality in children after LTx. Adolescent age, OB (non-retransplant) diagnosis, and graft rejection within 1-yr post-LTx are significant predictors of developing BOS. Early development of BOS (within 3yrs post-LTx) resulted in significantly worse graft survival than later development.