Outcomes of Simultaneous Liver-Kidney Transplantation Using Kidneys of Deceased Donors With Acute Kidney Injury

Differential in Kidney Graft Years on the Basis of Solitary Kidney, Simultaneous Liver-Kidney, and Kidney-after-Liver Transplants

BACKGROUND

The number of simultaneous liver-kidney (SLK) transplants has significantly increased in the United States. There has also been an increase in kidney-after-liver transplants associated with 2017 policy revisions aimed to fairly allocate kidneys after livers. SLK and kidney-after-liver candidates are prioritized in allocation policy for kidney offers ahead of kidney-alone candidates.

METHODS

We compared kidney graft outcomes of kidney-alone transplant recipients with SLK and kidney-after-liver transplants using paired kidney models to mitigate differences among donor risk factors. We evaluated recipient characteristics between transplant types and calculated differential graft years using restricted mean survival estimates.

RESULTS

We evaluated 3053 paired donors to kidney-alone and SLK recipients and 516 paired donors to kidney-alone and kidney-after-liver recipients from August 2017 to August 2022. Kidney-alone recipients were younger, more likely on dialysis, and Black race. One-year and 3-year post-transplant kidney graft survival for kidney-alone recipients was 94% and 86% versus SLK recipients 89% and 80%, respectively, P < 0.001. One-year and 3-year kidney graft survival for kidney-alone recipients was 94% and 84% versus kidney-after-liver recipients 93% and 87%, respectively, P = 0.53. The additional kidney graft years for kidney-alone versus SLK transplants was 21 graft years/100 transplants (SEM=5.0) within 4 years post-transplantation, with no significant difference between kidney-after-liver and kidney-alone transplants.

CONCLUSIONS

Over a 5-year period in the United States, SLK transplantation was associated with significantly lower kidney graft survival compared with paired kidney-alone transplants. Most differences in graft survival between SLK and kidney-alone transplants occurred within the first year post-transplantation. By contrast, kidney-after-liver transplants had comparable graft survival with paired kidney-alone transplants.

Center variations in patient selection for simultaneous heart-kidney transplantation

There are no established regulations governing patient selection for simultaneous heart-kidney (SHK) transplantation, creating the potential for significant center-level variations in clinical practice.

METHODS

Using the United Network for Organ Sharing (UNOS) Standard Transplant Analysis and Research (STAR) file, we examined practice trends and variations in patient selection for SHK at the center level between January 1, 2004 and March 31, 2019.

RESULTS

Overall, SHK is becoming more common with most centers performing heart transplants also performing SHK. Among patients who underwent heart transplant who were receiving dialysis, the rate of SHK varied from 22% to 86% at the center level. Among patients not on dialysis, the median estimated glomerular filtration rate (eGFR) of patients receiving SHK varied between 19 and 59 mL/min/1.73 m² . When adjusting for other factors, the odds of SHK varied 57-fold between the highest and lowest SHK performing centers.

CONCLUSION

Variation in SHK at the center level suggests the need for national guidelines around the selection of patients for SHK.