The number of simultaneous liver-kidney transplants (SLKT) for end-stage liver disease (ESLD) with renal failure is rising. The overall utility of kidneys used in this setting has not been quantified. We hypothesize:

1) Kidneys allocated as SLKT have shorter graft survival than do kidneys allocated as kidney (Ki) or kidney-pancreas (KP) transplants.

2) Each kidney, if allocated as Ki/KP, would offer a high benefit as measured by life-year-from-transplant (LYFT).

Methods

Deceased donor kidney pairs from 1/1/1995 through 12/3/2014, in which one kidney is utilized in SLKT and the other in kidney (Ki) or kidney-pancreas (KP) transplantation, were identified in Scientific Registry of Transplant Recipients. Excluded were pediatric recipients, other multi-organ transplants, SLKT for metabolic disorders or amyloidosis, and SLKT with pre-transplant dialysis duration >90 days.

The primary outcome was 10-year mean graft survival by transplant type, estimated from flexible parametric models restricted to 10-year follow-ups adjusted for donor and recipient characteristics. Graft survival was partitioned into graft failure and death using a competing risk framework. Expected LYFT per kidney was calculated as a weighted average based on Wolfe et al.'s projections and baseline characteristics of our matched Ki/KP cohort.

We matched 3299 SLKT cases to 2617 Ki and 682 KP cases. Kidneys allocated to KP/SLKT pairs were of higher quality than kidneys allocated to Ki/SLKT pairs (median KDRI 0.75 vs 0.88, p<0.001). Compared to Ki and KP recipients, SLKT recipients were more likely to be male, white, older, have a private insurer, and not be on dialysis at time transplant (<0.001).

Median graft survival exceeds 9 years in all transplant groups. SLKT resulted in 1.24 (95% C.I. 0.79-1.69) and 0.46 (95% C.I. -0.61-1.52) fewer years per graft compared to Ki and KP. Graft loss was driven by death in SLKT and by graft failure in Ki/KP. The median expected LYFT per kidney used in SLKT was 5.99 if allocated to a Ki and 9.31 if allocated to a KP candidate.

Conclusion

In the decade post-transplant, kidneys allocated to SLKT for renal failure in ESLD experience a modestly reduced survival compared to those allocated to Ki. The potential LYFT to be gained per kidney for Ki/KP candidates is substantial. Further studies are needed to quantify the benefit of SLKT over liver transplant alone.

CITATION INFORMATION: Cheng X, Stedman M, Kim W, Tan J. Utility in Treating Renal Failure in End-Stage Liver Disease with Simultaneous Liver-Kidney Transplantation. Am J Transplant. 2016;16 (suppl 3).

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