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

Liver transplantation (LT) is the 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. We analyzed outcomes of recipients of ABO-I LT using the Society of Pediatric Liver Transplantation (SPLIT) registry from 2011 to 2022, a prospective, multicenter database capturing over 75% of pediatric LTs in the United States and Canada. Clinical characteristics, posttransplant complications, and graft and patient survival were compared between matched ABO-I and ABO-compatible (ABO-C) recipients. Recipients of ABO-I transplant were matched 1:5 with recipients of ABO-C using year of transplant, age, and clinical status at the time of transplant. A center-level survey assessed institutional practices regarding ABO-I LT. Among 3372 pediatric recipients of LT, 155 received ABO-I grafts and were matched to 775 recipients of ABO-C grafts. Recipients of ABO-I had higher rates of ventilator support, parenteral nutrition, and ICU care at the time of transplant compared with recipients of ABO-C. There was no statistically significant difference in 3-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. Outcomes for pediatric recipients of ABO-I and ABO-C LT 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.