Simultaneous Liver-Kidney Transplant: Too Many or Just Enough?

Novel indications for referral and care for simultaneous liver kidney transplant recipients

PURPOSE OF REVIEW

Kidney dysfunction is challenging in liver transplant candidates to determine whether it is reversible or not. This review focuses on the pertinent data on how to best approach liver transplant candidates with kidney dysfunction in the current era after implementing the simultaneous liver kidney (SLK) allocation policy and safety net.

RECENT FINDINGS

The implementation of the SLK policy inverted the steady rise in SLK transplants and improved the utilization of high-quality kidneys. Access to kidney transplantation following liver transplant alone (LTA) increased with favorable outcomes. Estimating GFR in liver transplant candidates remains challenging, and innovative methods are needed. SLK provided superior patient and graft survival compared to LTA only for patients with advanced CKD and dialysis at least 3 months. SLK can provide immunological protection against kidney rejection in highly sensitized candidates. Post-SLK transplant care is complex, with an increased risk of complications and hospitalization.

SUMMARY

The SLK policy improved kidney access and utilization. Transplant centers are encouraged, under the safety net, to reserve SLK for liver transplant candidates with advanced CKD or dialysis at least 3 months while allowing lower thresholds for highly sensitized patients. Herein, we propose a practical approach to liver transplant candidates with kidney dysfunction.

Simultaneous Liver-Kidney Transplantation

End-stage kidney disease (ESKD) after liver transplantation is associated with high morbidity and mortality. This increase in mortality can be offset by performing a kidney transplant at the time of the liver transplant in select cases. Accordingly, Margreiter and colleague; s performed the first simultaneous liver-kidney (SLK) transplant in 1983. The number of SLK transplants has increased by more than 300% since then. In 1990%, 1.7% of all liver transplants in the United States were SLK transplants which increased to 9.9% by 2016. This steep increase was likely due to the implementation of the model of end-stage liver disease (MELD) scoring system in 2002, which is heavily weighted by serum creatinine.

Hepatorenal syndrome in acute-on-chronic liver failure with acute kidney injury: more questions requiring discussion

In cirrhosis with ascites, hepatorenal syndrome (HRS) is a specific prerenal dysfunction unresponsive to fluid volume expansion. Acute-on-chronic liver failure (ACLF) comprises a group of clinical syndromes with multiple organ failure and early high mortality. There are differences in the characterization of ACLF between the Eastern and Western medical communities. Patients with ACLF and acute kidney injury (AKI) have more structural injuries, contributing to confusion in diagnosing HRS-AKI. In this review, we discuss progress in the pathogenesis, diagnosis, and management of HRS-AKI, especially in patients with ACLF. Controversy regarding HRS-AKI in ACLF and acute liver failure, hepatic carcinoma, shock, sepsis, and chronic kidney disease is also discussed. Research on the treatment of HRS-AKI with ACLF needs to be more actively pursued to improve disease prognosis.

Paradigm Change in Liver Transplantation Practice After the Implementation of the Liver-Kidney Allocation Policy

The Organ Procurement and Transplantation Network (OPTN)/United Network for Organ Sharing (UNOS) policy regarding kidney allocation for liver transplantation (LT) patients was implemented in August 2017. This study evaluated the effects of the simultaneous liver-kidney transplantation (SLKT) policy on outcomes in LT alone (LTA) patients with kidney dysfunction. We analyzed adult primary LTA patients with kidney dysfunction at listing (estimated glomerular filtration rate [eGFR] less than 30 mL/minute or dialysis requirement) between January 2015 and March 2019 using the OPTN/UNOS registry. Waitlist practice and kidney transplantation (KT) listing after LTA were compared between prepolicy and postpolicy groups. There were 3821 LTA listings with eGFR <30 mL/minute included. The daily number of listings on dialysis was significantly higher in Era 2 (postpolicy group) than Era 1 (prepolicy group) (1.21/day versus 0.95/day; P < 0.001). Of these LTA listings, 90-day LT waitlist mortality, LTA probability, and 1-year post-LTA survival were similar between eras. LTA recipients in Era 2 had a higher probability for KT listing after LTA than those in Era 1 (6.2% versus 3.9%; odds ratio [OR], 3.30; P < 0.001), especially those on dialysis (8.4% versus 2.0%; OR, 4.38; P < 0.001). Under the safety net rule, there was a higher KT probability after LTA (26.7% and 53% at 6 months in Eras 1 and 2, respectively; P = 0.02). After the implementation of the policy, the number of LTA listings among patients on dialysis increased significantly. While their posttransplant survival did not change, KT listing after LTA increased. The safety net rule led to high KT probability and a low waitlist mortality rate in patients who were listed for KT after LTA. These results suggest that the policy successfully achieved the goals of providing appropriate opportunities of KT for LT patients, which did not compromise LTA waitlist or posttransplant outcomes in patients with kidney dysfunction and provided KT opportunities if patients developed kidney failure after LTA.

New OPTN Simultaneous Liver-Kidney Transplant (SLKT) Policy Improves Racial and Ethnic Disparities

(1) Background: On 10 August 2017, the Organ Procurement and Transplantation Network (OPTN) adopted standardized eligibility criteria to properly determine which transplant candidates should undergo Simultaneous Liver-Kidney Transplant (SLKT). Racial and ethnic disparities have not been examined after 2017. Therefore, using the United Network for Organ Sharing (UNOS), we aim to evaluate post-graft survival outcomes among Caucasians, African Americans, and Hispanics. (2) Methods: Kaplan-Meier curves and Cox regression models are used to compare post-transplant graft survival for Caucasians, African Americans (AAs), and Hispanics. Competing risk analysis is used to evaluate the cumulative incidence of death or re-transplantation with re-transplantation and death as competing risks. (3) Results: On multivariate Cox regression analysis, no differences in graft survival are found in AA (hazard ratio (HR): 1.30; 95% CI: 0.74-2.29 p = 0.354) or Hispanics (HR: 1.18; 95% CI: 0.70-2 p = 0.520) compared to Caucasians after 2017. On competing risk analysis of the risk of death with re-transplantation as a competing risk, no difference is found between ethnic minorities after 2017. There is a similar finding from competing risk analysis of the risk of re-transplantation with death as a competing risk. (4) Conclusion: After introducing standardized eligibility criteria for SLKT allocation, the post-graft survival outcomes remain similar between the different racial and ethnic groups, displaying the benefits of adopting such policy in 2017.

Liver alone or simultaneous liver-kidney transplant? Pretransplant chronic kidney disease and post-transplant outcome - a retrospective study

The new Organ Procurement and Transplant Network/United Organ Sharing Network (OPTN/UNOS) simultaneous liver-kidney transplant (SLK) policy has been implemented. The aim of this study was to review liver transplant outcomes utilizing the new SLK policy. Liver transplant alone (LTA) and SLK patients between 2009 and 2015 were reviewed. Graft survival and post-transplant kidney function were investigated among LTA patients meeting the chronic kidney disease (CKD) criteria of the new policy (LTA-CKD group). To validate our findings, we reviewed and applied our analysis to the OPTN/UNOS registry. A total of 535 patients were eligible from our series. The LTA-CKD group (n = 27) showed worse 1-year graft survival, compared with the SLK group (n = 44), but not significant (81% vs. 93%, P = 0.15). The LTA-CKD group significantly increased a risk of post-transplant dialysis (odds ratio = 5.59 [95% CI = 1.27-24.7], P = 0.02 [Ref. normal kidney function]). Post-transplant dialysis was an independent risk factor for graft loss (hazard ratio = 7.25, 95% CI = 3.3-15.91, P < 0.001 [Ref. SLK]). In the validation analysis based on the OPTN/UNOS registry, the hazard of 1-year-graft loss in the LTA-CKD group (n = 751) was 34.8% higher than the SLK group (n = 2856) (hazard ratio = 1.348, 95% CI = 1.157-1.572, P < 0.001). Indicating SLK for patients who meet the CKD criteria may significantly improve transplant outcomes.

A Review of Organ Transplantation: Heart, Lung, Kidney, Liver, and Simultaneous Liver-Kidney

Heart, lung, kidney, liver, and simultaneous liver-kidney transplants share many features. They all follow the same 7-step process, the same 3 immunosuppressant medications, and the same reason for organ transplantation. Organs are transplanted because of organ failure. The similarities end there. Each organ has its unique causes for failure. Each organ also has its own set of criteria that must be met prior to transplantation. Simultaneous liver-kidney transplant criteria vary per transplant center but are similar in nature. Both the criteria required and the 7-step process are described by the United Network of Organ Sharing, which is a private, nonprofit organization, under contract with the US Department of Health and Human Services. Its function is to increase the number of transplants, improve survival rates after transplantation, promote safe transplant practices, and endorse efficiency. The purpose of this article is to review the reasons transplant is needed, specifically heart, lung, kidney, liver, and simultaneous liver-kidney, and a brief overview of the transplant process including criteria used, contraindications, and medications prescribed.

Outcomes of liver transplantation in patients with hepatorenal syndrome

Hepatorenal syndrome (HRS) plays an important role in patients with liver cirrhosis on the wait list for liver transplantation (LT). The 1 and 5-year probability of developing HRS in cirrhotic with ascites is 20% and 40%, respectively. In this article, we reviewed current concepts in HRS pathophysiology, guidelines for HRS diagnosis, effective treatment options presently available, and controversies surrounding liver alone vs simultaneous liver kidney transplant (SLKT) in transplant candidates. Many treatment options including albumin, vasoconstrictors, renal replacement therapy, and eventual LT have remained a mainstay in the treatment of HRS. Unfortunately, even after aggressive measures such as terlipressin use, the rate of recovery is less than 50% of patients. Moreover, current SLKT guidelines include: (1) estimation of glomerular filtration rate of 30 mL/min or less for 4-8 wk; (2) proteinuria > 2 g/d; or (3) biopsy proven interstitial fibrosis or glomerulosclerosis. Even with these updated criteria there is a lack of consistency regarding long-term benefits for SLKT vs LT alone. Finally, in regards to kidney dysfunction in the post-transplant setting, an estimation of glomerular filtration rate < 60 mL/min per 1.73 m² may be associated with an increased risk of patients having long-term end stage renal disease. HRS is common in patients with cirrhosis and those on liver transplant waitlist. Prompt identification and therapy initiation in transplant candidates with HRS may improve post-transplantation outcomes. Future studies identifying optimal vasoconstrictor regimens, alternative therapies, and factors predictive of response to therapy are needed. The appropriate use of SLKT in patients with HRS remains controversial and requires further evidence by the transplant community.