Difference in Survival in Early Kidney after Liver Transplantation Compared with Simultaneous Liver-Kidney Transplantation: Evaluating the Potential of the "Safety Net"

Background: Decisions on who requires simultaneous liver-kidney (SLK) transplantation are controversial. United Network for Organ Sharing implemented a "safety net" in 2017 providing prioritization on the kidney waitlist for patients with renal failure after liver transplantation. We aimed to compare survival after early kidney after liver transplantation (KALT) and SLK.

Study design: We compared SLK, KALT, and liver transplantation alone (LTA) in adult patients who underwent deceased donor (DD) liver transplantation in the US, from 2002 to 2018. Early KALT was defined as 60 to 365 days between liver and subsequent kidney transplantation (reflecting safety net listing criteria). Patients who died within 60 days were excluded to mitigate immortal time bias favoring KALT.

Results: There were 6,774 SLK, 120 KALT at 60 to 365 days, and 11,501 LTA. Early KALT had equivalent survival compared with SLK, both for all KALT (hazard ratio [HR] 0.58, 95% CI 0.34-1.00, p = 0.05) and for DD KALT only (HR 0.72, 95% CI 0.37-1.38, p = 0.32). Simultaneous liver-kidney transplantation was associated with improved survival compared with LTA (HR 0.82. 95% CI 0.76-0.87, p < 0.01). Early KALT was associated with a greater reduction in mortality compared with LTA, but this was not significant (HR 0.58, 95% CI 0.39-1.00, p = 0.05). There was a lower proportion of early KALT in African Americans relative to SLK transplantations (7% vs 16%, p = 0.04).

Conclusions: Early KALT has equivalent survival compared with SLK transplantation, both for all KALT and for DD KALT only, supporting the promise of the "safety net." There was a lower proportion of African-American patients undergoing early KALT, indicating the importance of monitoring access to early KALT under the "safety net" policy.