Status Exceptions and Misalignment of Medical Urgency in U.S. Pediatric Heart Transplantation.

Abstract

Pediatric heart transplant candidates experience high waitlist mortality, in part because of limited availability of appropriate donor hearts. Transplant physicians can request status exceptions to increase priority for candidates, but this practice may contribute to overcrowding of high-priority statuses. In 2021, the National Heart Review Board (NHRB) was established to standardize exception review, but its impact remains unknown. The goal of this study was to determine whether exceptions are granted to children at high risk of death on the waitlist and the impact of the NHRB on outcomes. Using Organ Procurement and Transplantation Network data, we identified all pediatric heart transplant candidates listed March 2016 through March 2025. We estimated the association between status exceptions and waitlist mortality using mixed-effects Cox proportional hazards models and compared concordance indices for the current system vs a hypothetical system without exceptions. Among 6,026 candidates, 745 (12.4%) died or deteriorated and 1,668 (27.7%) received exceptions. Exception recipients had a significantly lower waitlist mortality risk than standard criteria patients (HR: 0.41; 95% CI: 0.31-0.55; P < 0.001) and the NHRB's impact on this association was nonsignificant (P = 0.62). We observed significant heterogeneity in waitlist mortality within status 1A, with exception recipients having the highest survival. When modeling waitlist mortality, the concordance index improved from 0.694 (95% CI: 0.682-0.706) with exceptions to 0.713 (95% CI: 0.700-0.724) without exceptions (P < 0.001). Pediatric heart transplant candidates granted status exceptions have significantly lower medical urgency than those meeting standard criteria. Implementation of a national review board did not result in improved alignment between waitlist mortality and listing status.