Assessment of HLA matching algorithm PIRCHE‐II on liver transplantation outcomes

Background and aims For liver transplantations, HLA-matching is not routinely performed because observed effects have been inconsistent. Nevertheless, long-term liver transplantation outcomes remain suboptimal. The availability of a more precise HLA-matching algorithm, PIRCHE-II, now enables robust assessment of the association between HLA matching and liver transplantation outcomes. Methods We performed a single-center retrospective cohort study of 736 liver transplantation patients. Associations between PIRCHE-II and HLAMatchmaker scores and mortality, graft loss, acute and chronic rejection, ischemic cholangiopathy, and disease recurrence were evaluated with cox proportional hazard models. Associations between PIRCHE-II with 1-, 2-, and 5-year outcomes and severity of acute rejection were assessed with logistic and linear regression analyses, respectively. Subgroup analyses were performed for autoimmune and non-autoimmune indications, and ages ≤30, or >30. Results PIRCHE-II and HLAMatchmaker scores were not associated with any of the outcomes. However, patients transplanted for autoimmune disease showed more acute rejection and graft loss, and these risks negatively associated with age. Rhesus mismatch more than doubled the risk of disease recurrence. Moreover, PIRCHE-II was inversely associated with graft loss in the subgroup of patients aged ≤30 with autoimmune indications. Conclusion The absence of associations between PIRCHE-II and HLAMatchmaker scores and the studied outcomes refutes the need for HLA matching for liver (stem cell) transplantations for non-autoimmune disease. For autoimmune disease, the activated immune system seems to increase risks of acute rejection and graft loss. Our results may suggest benefits of transplanting with rhesus matched but PIRCHE-II mismatched donor livers.