ABO-Nonidentical Liver Transplantation in the United States

Under the United Network for Organ Sharing (UNOS) policy, deceased donor livers may be offered to ABO-nonidentical candidates at each given Model for End-Stage Liver Disease (MELD) score and to blood type B candidates at MELD ≥30. To evaluate ABO-nonidentical liver transplantation (LT) in the United States, we examined all adult LT non-status 1 candidates, recipients and deceased liver donors from 2013 to 2015. There were 34 920 LT candidates (47% type O, 38% type A, 12% type B, 3% type AB) and 10 479 deceased liver donors (47% type O, 38% type A, 12% type B, 3% type AB). ABO-nonidentical LT occurred in 2%, 3%, 20% and 36% of types O, A, B and AB recipients, respectively, which led to a net liver loss of 6% for type O and 2% for type A recipients but a net liver gain of 14% for type B and 55% for type AB recipients. The LT MELD scores of ABO-identical versus -nonidentical recipients were 29 versus 34 for type O, 29 versus 19 for type A, 25 versus 38 for type B, and 22 versus 28 for type AB (p < 0.01). ABO-nonidentical LT increased liver supply for candidates with blood types B and AB but decreased supply for type O and A candidates. We urge refinement of UNOS policy surrounding ABO-nonidentical LT.