A Paired Kidney Analysis of Multiorgan Transplantation: Implications for Allograft Survival

Background. United Network for Organ Sharing multiorgan transplantation allocation policy allows sequestration of a kidney by another solid organ regardless of the priority of the candidate for the kidney allograft. The implications of this policy for kidney allograft survival are not well understood. Methods. We conducted a retrospective cohort analysis of pairs of deceased donor kidney transplants where 1 kidney was allocated to a simultaneous liver-kidney (SLK) or simultaneous heart-kidney (SHK) recipient and the contralateral kidney to a kidney transplant alone (KTA) recipient (cohort from February 2002 to December 2010). Graft and patient survivals were assessed with Cox regression models. Results. There were 1998 SLK and 276 SHK transplants with matching KTA transplants. Five-year kidney graft (64% [SLK] vs 75% [KTA], P < 0.001) and patient survivals (66% [SLK] vs 81% [KTA], P < 0.001) were significantly lower in SLK versus KTA recipients of the contralateral kidney. Among the entire cohort of SLK in this analysis, the cumulative difference in graft survival 1 year after transplant was 115 years, and by 5 years, the difference increased to 1062 years. Among the SHK arm of our study, 5-year graft survival (72% [SHK] vs 73% [KTA], P = 0.71) did not significantly differ, although patient survival (75% [SHK] vs 84% [KTA], P = 0.02) was higher in KTA recipients. Conclusions. Kidney graft survival is inferior among SLK relative to KTA, but not SHK. Multiorgan transplantation allocation may not be congruent with the intention of new kidney allocation policies that attempt to maximize survival after kidney transplantation.