Outcomes in pediatric recipients of ABO-incompatible liver transplants: An analysis of the SPLIT registry

BACKGROUND: Liver transplantation (LT) is standard of care for children with end-stage liver disease, but waitlist mortality remains high, especially among infants. ABO-incompatible (ABO-I) LT offers a strategy to expand the donor pool, though concerns over antibody-mediated rejection have limited widespread use. METHODS: We analyzed outcomes of ABO-I LT recipients using the Society of Pediatric Liver Transplantation (SPLIT) registry from 2011-2022, a prospective, multicenter database capturing over 75% of pediatric LTs in the United States and Canada. Clinical characteristics, post-transplant complications, and graft and patient survival were compared between matched ABO-I and ABO-compatible (ABO-C) recipients. ABO-I transplant recipients were matched 1:5 with ABO-C recipients using year of transplant, age and clinical status at the time of transplant. A center-level survey assessed institutional practices regarding ABO-I LT. RESULTS: Among 3,372 pediatric LT recipients, 155 received ABO-I grafts and were matched to 775 recipients of ABO-C grafts. ABO-I recipients had higher rates of ventilator support, parenteral nutrition, and ICU care at time of transplant compared to ABO-C recipients. There was no statistically significant difference in three-year graft (87.8% vs. 92.6%, p=0.06) or patient survival (93.9% vs. 96.6%, p=0.11) between ABO-I and ABO-C groups. In children ≤2 years of age, there was a higher incidence of early portal venous thrombosis in the ABO-I group (8.5% vs. 3.7%, p=0.025). Survey responses revealed substantial variability in center ABO-I eligibility criteria, desensitization protocols, and immunosuppressive strategies. CONCLUSIONS: Outcomes for pediatric ABO-I and ABO-C LT recipients within the SPLIT registry are comparable, supporting broader implementation of ABO-I LT to reduce pediatric waitlist mortality. Variability in institutional practices underscores the need for prospective studies to inform standardized protocols and optimize outcomes.