Kidney after liver transplantation does not have an increased risk of rejection compared to liver alone

BackgroundSimultaneous liver kidney (SLK) transplant protects against acute cellular rejection. In 2017, UNOS implemented a "safety net" policy to allow patients with renal recovery to avoid renal transplantation. Whether kidney after liver transplantation (KALT) increases the risk of rejection is unknown.MethodsWe performed a retrospective analysis of the Organ Procurement and Transplantation Network (OPTN) database of adult patients who received liver transplant, SLK or KALT between 2010 and 2020. We examined rejection of the liver within 6 months and 1 year of the liver transplant, as well as rejection of the kidney within 6 months and 1 year of receiving the kidney, as well as patient and graft loss.ResultsSixty-six thousand seventy-nine patients were transplanted; 60 168 with liver transplant alone, 5627 with SLK, and 284 with KALT. Acute or chronic liver rejection rates within 6 or 12 months were statistically higher in the KALT group (10.0% and 10.9%) compared to the SLK group (6.1% and 7.5%), but comparable to the LTA group (9.3% and 11.1%). Kidney rejection and graft survival rates were not different. Liver graft survival was worse in KALT than SLK or LTA (Kaplan-Meier estimates .61 vs. .89 and .90), but these patients were more ill at the time of transplantation. KDPI and LDRI scores were notably lower in the SLK than KALT group. Patient survival was not clinically different between the groups.ConclusionKALT does not increase the risk of acute or chronic kidney rejection. SLK has a lower risk of early liver rejection, but this effect diminishes by one year to being not clinically different compared to KALT. Given that KALT is immunologically safe, and potentially avoids unnecessary renal graft use, it should be preferred over SLK.Brief summaryPatients undergoing sequential kidney after liver transplant do not have an increased risk of liver or kidney rejection when compared to liver transplant alone or simultaneous liver and kidney transplant.