Comparison of renal allograft outcomes in combined liver-kidney transplantation versus subsequent kidney transplantation in liver transplant recipients: Analysis of UNOS database

Background. There may be an allograft-enhancing effect by the liver on the renal allograft in the setting of simultaneous combined liver-kidney transplantation (CLKT) from the same donor. This study was performed to investigate whether an existing liver allograft could protect a kidney allograft from immunologic injury due to histoincompatibility in liver transplant recipients who received sequential kidney transplantation (KALT). Methods. Using the United Network for Organ Sharing database covering January 1996 to December 2003, outcomes of 352 KALT were compared to 1,136 CLKT. Incidence of acute and chronic rejection and rejection-free renal graft survival was compared between two groups. Results. Renal half-life of KALT allografts was shorter than CLKT group (6.6 +/- 0.9 vs. 11.7 +/- 1.3 years, P < 0.001). Incidence of chronic rejection in KALT group was higher than CLKT group (4.6 vs. 1.2%, P < 0.001). One and three-year rejection-free renal graft survival of KALT and CLKT groups were different (77% and 67% KALT vs. 85% and 78% CLKT, respectively; P < 0.001). Among human leukocyte antigen mismatched and sensitized patients, rejection-free renal graft survival of KALT group was inferior to the CLKT group (75% at 1 year and 61% 3 years vs. 86% at 1 year and 79% 3 years, P < 0.001). Conclusion. Liver allograft provided renal graft immunoprotection if both organs are transplanted simultaneously (immunogenetic identity), but not for kidneys transplanted subsequently.