A Tale of Two Kidneys: Differences in Graft Survival for Kidneys Allocated to Simultaneous Liver Kidney Transplant Compared with Contralateral Kidney from the Same Donor

Background Renal graft lifespan in simultaneous liver kidney transplant (SLK) is generally thought to be shorter than in kidney transplant (KT) alone, raising questions about the utility of SLK. This study aims to estimate what would be the outcome for a kidney allocated to SLK were it instead allocated to KT. Method Using United Network for Organ Sharing data, recipients of SLK from 2003-2012 were paired with the recipient who received the partner kidney from the same donor in a kidney or kidney-pancreas transplant for analysis. The primary outcomes were long-term patient and renal graft survival. This was investigated using modified multivariable Cox regression which allowed for changes in the hazard ratio (HR) associated with SLK over time (non-proportional hazards), accounted for the paired nature of the study, and adjusted for differences in recipient characteristics. Results There were 3721 recipients in each group. Ninety day mortality was 8.0% for SLK vs. 1.9% for KT recipients (p Conclusion Although kidneys allocated to SLK vs. KT demonstrate worse short-term survival, this risk appears to be reversed when followup is extended long-term.