Early Kidney Allograft Failure After Simultaneous Liver-kidney Transplantation: Evidence for Utilization of the Safety Net?

Simultaneous liver-kidney transplantation: future perspective

BACKGROUND

The aims of this narrative review were (i) to describe the current indications of SLKT, (ii) to report evolution of SLKT activity, (iii) to report the outcomes of SLKT, (iv) to explain the immune-protective effect of liver transplant on kidney transplant, (v) to explain the interest of delay kidney transplantation, using hypothermic machine perfusion (HMP), (vi) to report kidney after liver transplantation (KALT) indications and (vii) to describe the value of the increase in the use of extended criteria donors (ECD) and particular controlled donation after circulatory death (cDCD) transplant, thanks to the development of new organ preservation strategies.

METHOD

Electronic databases were screened using the keywords "Simultaneous", "Combined", "kidney transplantation" and "liver transplantation". The methodological and clinical heterogeneity of the included studies meant that meta-analysis was inappropriate.

RESULTS

 A total of 1,917 publications were identified in the literature search. Two reviewers screened all study abstracts independently and 1,107 of these were excluded. Thus, a total of 79 full text articles were assessed for eligibility. Of these, 21 were excluded. In total, 58 studies were included in this systematic review.

CONCLUSIONS

 Simultaneous liver-kidney transplantation has made a significant contribution for patients with dual-organ disease. The optimization of indication and selection of SLKT patients will reduce futile transplantation. Moreover, increasing the use of transplants from extended criteria donors, in particular cDCD, should be encouraged, thanks to the development of new modalities of organ preservation.

Simultaneous Liver and Kidney Transplantation in Patients Aged 70 y and Older: Proceed With Caution

Background

The number of elderly patients aged 70 y and older with liver and kidney failure is increasing, mainly because of increasing prevalence of metabolic dysfunction-associated steatohepatitis. At present, limited data are available on the outcomes of elderly patients who fit the criteria for dual organ transplantation since the implementation of the simultaneous liver and kidney (SLK) allocation policy.

Methods

We performed a retrospective analysis of the Organ Procurement and Transplantation Network database of adults aged 18 y and older undergoing SLK and kidney transplantation only from August 11, 2017, to December 31, 2022. We examined patient and graft survivals and compared the outcomes of the recipients aged 70 y and older undergoing SLK transplantation to those who received kidney transplant alone and kidney after liver transplant.

Results

During the study period, there has been a significant rise in the number of patients aged 70 y and older undergoing SLK transplantation, with 6 patients undergoing SLK transplantation in 2017 and 63 in 2021. Patients aged 70 y and older had significantly lower survival with 82.9% at 1 y and 66.5% at 3 y compared with 89.3% and 78.8% in the 50-69 y age group and 93.2% and 88.6% in the 18-49 y age group, respectively. Overall, kidney allograft survival was significantly lower in the 70 y and older group, with 80.9% at 1 y and 66.4% at 3 y compared with 91.1% and 75.5%, respectively, in those undergoing kidney transplant alone. There was no difference in kidney allograft survival in those undergoing SLK and kidney after liver transplantation.

Conclusions

Although the outcomes are inferior in recipients of SLK transplant aged 70 y and older, chronologic age should not preclude them from undergoing transplantation. Kidney transplantation after liver transplantation could be considered to avoid futile transplants.

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

BACKGROUND

Simultaneous 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.

METHODS

We 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.

RESULTS

Sixty-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.

CONCLUSION

KALT 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 SUMMARY

Patients 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.

Differential Impact of the UNOS Simultaneous Liver-kidney Transplant Policy Change Among Patients With Sustained Acute Kidney Injury

BACKGROUND

Simultaneous liver-kidney transplant (SLK) allocation policy in the United States was revised in August 2017, reducing access for liver transplant candidates with sustained acute kidney injury (sAKI) and potentially adversely impacting vulnerable populations whose true renal function is overestimated by commonly used estimation equations.

METHODS

We examined national transplant registry data containing information for all liver transplant recipients from June 2013 to December 2021 to assess the impact of this policy change using instrumental variable estimation based on date of listing.

RESULTS

Posttransplant survival was compared for propensity-matched patients with sAKI who were only eligible for liver transplant alone (LTA_post; n = 638) after the policy change but would have been SLK-eligible before August 2017, with similar patients who were previously able to receive an SLK (SLK; n = 319). Overall posttransplant patient survival was similar at 3 y (81% versus 80%; P = 0.9). However, receiving an SLK versus LTA increased survival among African Americans (87% versus 61% at 3 y; P = 0.029). A trend toward survival benefit from SLK versus LTA, especially later in the follow-up period, was observed in recipients ≥ age 60 (3-y survival: 84% versus 76%; P = 0.2) and women (86% versus 80%; P = 0.2).

CONCLUSIONS

The 2017 United Network for Organ Sharing SLK Allocation Policy was associated with reduced survival of African Americans with end-stage liver disease and sAKI and, potentially, older patients and women. Our study suggested the use of race-neutral estimation of renal function would ameliorate racial disparities in the SLK arena; however, further studies are needed to reduce disparity in posttransplant outcomes among patients with liver and kidney failure.

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.

One size does not fit all: Differential benefits of simultaneous liver-kidney transplantation by eligibility criteria

Standard eligibility criteria for simultaneous liver-kidney transplantation (SLK) are in place in the United States. We hypothesize that the benefit associated with SLK over liver transplant alone differs by patient, depending on the specific SLK criteria met. We analyzed a retrospective US cohort of 5446 adult liver transplant or SLK recipients between January 1, 2015, and December 31, 2018, who are potentially qualified for SLK. Exposure was a receipt of SLK. We tested effect modification by the specific SLK eligibility criteria met (end-stage kidney disease, acute kidney injury, chronic kidney disease, or unknown). The primary outcome was death within 1 year of a liver transplant. We used a modified Cox regression analysis containing an interaction term of SLK * time from transplant. Two hundred ten (9%) SLK recipients and 351 (11%) liver-alone recipients died in 1 year. In the overall population, SLK was associated with a mortality benefit over liver transplant on the day of the transplant, without adjustment [HR: 0.59 (95% CI, 0.46-0.76)] and with adjustment [aHR: 0.50 (95% CI, 0.35-0.71)]. However, when SLK eligibility criteria were included, only in patients with end-stage kidney disease was SLK associated with a sustained survival benefit at day 0 [HR: 0.17 (0.08-0.35)] up to 288 (95% CI, 120-649) days post-transplant. Benefit within the first year post-transplant associated with SLK over liver-alone transplantation was only pronounced in patients with end-stage kidney disease but not present in patients meeting other criteria for SLK. A "strict SLK liberal Safety Net" strategy may warrant consideration at the national policy level.

Pros and Cons of the Safety Net Rule for Prioritization of Liver Transplant Recipients Who Receive Liver Alone Transplant but Develop End-Stage Renal Disease

The number of patients presenting with cirrhosis with kidney injury and the potential need for SLKT is increasing. In 2017, standardized criteria were implemented to identify candidates for SLKT as well as criteria for prioritizing LTA recipients for kidney transplant if they developed kidney failure, which is referred to as the 'safety net rule.' Goal of the safety net rule is to provide a pathway that provides increased priority to LTA recipients with renal failure who may have previously undergone SLKT. This article reviews the pros and cons of the safety net rule for liver transplant recipients who develop ESRD.

Optimal patient selection for simultaneous heart-kidney transplant: A modified cost-effectiveness analysis

Increasing rates of simultaneous heart-kidney (SHK) transplant in the United States exacerbate the overall shortage of deceased donor kidneys (DDK). Current allocation policy does not impose constraints on SHK eligibility, and how best to do so remains unknown. We apply a decision-analytic model to evaluate options for heart transplant (HT) candidates with comorbid kidney dysfunction. We compare SHK with a "Safety Net" strategy, in which DDK transplant is performed 6 months after HT, only if native kidneys do not recover. We identify patient subsets for whom SHK using a DDK is efficient, considering the quality-adjusted life year (QALY) gains from DDKs instead allocated for kidney transplant-only. For an average-aged candidate with a 50% probability of kidney recovery after HT-only, SHK produces 0.64 more QALYs than Safety Net at a cost of 0.58 more kidneys used. SHK is inefficient in this scenario, producing fewer QALYs per DDK used (1.1) than a DDK allocated for KT-only (2.2). SHK is preferred to Safety Net only for candidates with a lower probability of native kidney recovery (24%-38%, varying by recipient age). This finding favors the implementation of a Safety Net provision and should inform the establishment of objective criteria for SHK transplant eligibility.

Estimating Glomerular Filtration Rate in Cirrhosis Using Creatinine-Based and Cystatin C-Based Equations: Systematic Review and Meta-Analysis

Accurate estimation of kidney function in cirrhosis is crucial for prognosis and decisions regarding dual-organ transplantation. We performed a systematic review/meta-analysis to assess the performance of creatinine-based and cystatin C (CysC)-based eGFR equations compared with measured GFR (mGFR) in patients with cirrhosis. A total of 25 studies (n = 4565, 52.0 years, 37.0% women) comprising 18 equations met the inclusion criteria. In all GFR equations, the creatinine-based equations overestimated GFR (standardized mean difference, SMD, 0.51; 95% confidence interval [CI], 0.31-0.71) and CysC-based equations underestimated GFR (SMD, -0.3; 95% CI, -0.60 to -0.02). Equations based on both creatinine and CysC were the least biased (SMD, -0.14; 95% CI, -0.46 to 0.18). Chronic kidney disease-Epi-serum creatinine-CysC (CESC) was the least biased but had low precision and underestimated GFR by -3.6 mL/minute/1.73 m² (95% CI, -17.4 to 10.3). All equations significantly overestimated GFR (+21.7 mL/minute/1.73 m² ; 95% CI, 17.7-25.7) at GFR <60 mL/minute/1.73 m² ; of these, chronic kidney disease-Epi-CysC (10.3 mL/minute/1.73 m² ; 95% CI, 2.1-18.4) and GFR Assessment in Liver Disease (12.6 mL/minute/1.73 m² ; 95% CI, 7.2-18.0) were the least biased followed by Royal Free Hospital (15 mL/minute/1.73 m² ; 95% CI, 5.5-24.6) and Modification of Diet in Renal Disease 6 (15.7 mL/minute/1.73 m² ; 95% CI, 10.6-20.8); however, there was an overlap in the precision of estimates, and the studies were limited. In ascites, overestimation of GFR was common (+8.3 mL/minute/1.73 m² ; 95% CI, -3.1 to 19.7). However, overestimation of GFR by 10 to 20 mL/minute/1.73m² is common in patients with cirrhosis with most equations in ascites and/or kidney dysfunction. A tailored approach is required especially for decisions regarding dual-organ transplantation.

Current State of Multiorgan Transplantation and Implications for Future Practice and Policy

The incidence of kidney dysfunction has increased in liver transplant and heart transplant candidates, reflecting a changing patient population and allocation policies that prioritize the most urgent candidates. A higher burden of pretransplant kidney dysfunction has resulted in a substantial rise in the utilization of multiorgan transplantation (MOT). Owing to a shortage of available deceased donor kidneys, the increased use of MOT has the potential to disadvantage kidney-alone transplant candidates, as current allocation policies generally provide priority for MOT candidates above all kidney-alone transplant candidates. In this review, the implications of kidney disease in liver transplant and heart transplant candidates is reviewed, and current policies used to allocate organs are discussed. Important ethical considerations pertaining to MOT allocation are examined, and future policy modifications that may improve both equity and utility in MOT policy are considered.

A comparison between combined liver kidney transplants to liver transplants alone: A systematic review and meta-analysis

BACKGROUND

Since the introduction of the Model for End-stage Liver disease criteria in 2002, more combined liver kidney transplants are performed. Until 2017, no standard allocation policy for combined liver kidney transplant (CLKT) was available and each transplant center decided eligibility for CLKT or liver transplant alone (LTA) on a case-by-case basis. The aim of this systematic review was to compare the clinical outcomes of CLKT compared to LTA in patients with renal dysfunction.

METHODS

Databases were systematically searched for studies published between January 2010 and March 2021. Outcomes were expressed as risk ratios and pooled with a random-effects model. The primary outcome was patient survival.

RESULTS

Four studies were included. No differences were observed for mortality risk at 1 year (risk ratio (RR) 1.03 [confidence interval (CI) 0.97-1.09], 3 years (RR 1.06 [CI 0.99-1.13]) and 5 years (RR 1.08 [CI 0.98-1.19]). The risk of graft loss was similar in the first year (RR 1.10 [CI 0.93-1.30], while 3-year risk of graft loss was significantly lower in CLKT patients (RR 1.15 [CI 1.08-1.24]).

CONCLUSIONS

CLKT has similar short-term graft and patient survival as LTA in patients with renal dysfunction. More data is needed to decide from which KDIGO stage patients benefit the most from CLKT.

KDOQI US Commentary on the 2020 KDIGO Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation

Evaluation of patients for kidney transplant candidacy is a comprehensive process that involves a detailed assessment of medical and surgical issues, psychosocial factors, and patients' physical and cognitive abilities with an aim of balancing the benefits of transplantation and potential risks of surgery and long-term immunosuppression. There is considerable variability among transplant centers in their approach to evaluation and decision-making regarding transplant candidacy. The 2020 KDIGO (Kidney Disease: Improving Guidelines Outcome) clinical practice guideline on the evaluation and management of candidates for kidney transplantation provides practice recommendations that can serve as a useful reference guide to transplant professionals. The guideline, covering a broad range of topics, was developed by an international group of experts from transplant and nephrology through a review of literature published until May 2019. A work group of US transplant nephrologists convened by NKF-KDOQI (National Kidney Foundation-Kidney Disease Quality Initiative) chose key topics for this commentary with a goal of presenting a broad discussion to the US transplant community. Each section of this article has a summary of the key KDIGO guideline recommendations, followed by a brief commentary on the recommendations, their clinical utility, and potential implementation challenges. The KDOQI work group agrees broadly with the KDIGO recommendations but also recognizes and highlights the decision-making challenges that arise from lack of high-quality evidence and the need to balance equity with utility of organ transplantation.