High Center Volume Does Not Mitigate Risk Associated with Using High Donor Risk Organs in Liver Transplantation

Background: High-risk donor allografts increase access to liver transplant, but potentially reduce patient and graft survival.

Aims: It is unclear whether the risk associated with using marginal donor livers is mitigated by increasing center experience.

Methods: The United Network for Organ Sharing registry was queried for adult first-time liver transplant recipients between 2/2002 and 12/2015. High donor risk was defined as donor risk index >1.9, and 1-year patient and graft survival were compared according to donor risk index in small and large centers. Multivariable Cox regression estimated the hazard ratio (HR) associated with using high-risk donor organs, according to a continuous measure of annual center volume.

Results: The analysis included 51,770 patients. In 67 small and 67 large centers, high donor risk index predicted increased mortality (p = 0.001). In multivariable analysis, high-donor risk index allografts predicted greater mortality hazard at centers performing 20 liver transplants per year (HR 1.35; 95% CI 1.22, 1.49; p < 0.001) and, similarly, at centers performing 70 per year (HR 1.35; 95% CI 1.26, 1.43; p < 0.001). The interaction between high donor risk index and center volume was not statistically significant (p = 0.747), confirming that the risk associated with using marginal donor livers was comparable between smaller and larger centers. Results were consistent when examining graft loss.

Conclusion: At both small and large centers, high-risk donor allografts were associated with reduced patient and graft survival after liver transplant. Specific strategies to mitigate the risk of liver transplant involving high-risk donors are needed, in addition to accumulation of center expertise.