New Organ Allocation System for Combined Liver-Kidney Transplants and the Availability of Kidneys for Transplant to Patients with Stage 4-5 CKD

Combined Heart Kidney Transplantation Versus Heart Transplant in Patients with Renal Failure: Contemporary Insights and Future Perspectives

PURPOSE OF REVIEW

In this review, we aim to outline the criteria regarding the evaluation of patients with chronic renal disease (CKD) awaiting heart transplantation and discuss the outcomes of combined heart/kidney transplantation. Herein, we also review pathophysiology and risk factors that predispose to chronic kidney disease (CKD) and acute kidney injury (AKI) in patients with HF and after OHT.

RECENT FINDINGS

In patients with end-stage systolic heart failure (HF) and an estimated glomerular filtration rate (eGFR) < 30 mL/min/1.73 m2, orthotopic heart transplantation (OHT) alone is a relative contraindication, with a consensus that these patients are better served with heart-kidney transplant (HKT). However, there is significant variation between institutions regarding timing and indication for heart/kidney transplantation, with little data available to predict post-transplant outcomes. A Scientific Statement from American Heart Association was published detailing the indications, evaluation, and outcomes for Heart-Kidney Transplantation, and noted a steady rise in the incidence of heart/kidney dual organ transplants. Recently, the Organ Procurement and Transplantation Network (OPTN) Multi-Organ Transplantation Committee implemented a safety net policy for heart transplant recipients who do need meet criteria for simultaneous heart-kidney transplant in 2023 but with a likely need for sequential kidney transplantation. Optimization of organ distribution and patient outcomes after cardiac transplantation requires appropriate recipient selection. This review also outlines the criteria regarding the evaluation of patients with CKD awaiting heart transplantation and outcomes of combined HKT.

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.

Living Donor Liver Transplantation Alone Is Not Inferior to Combined Kidney Liver Transplant for Cirrhotic Patients With Chronic Kidney Disease

BACKGROUND

Chronic kidney disease (CKD) is common in patients with chronic liver disease (CLD) as is acute kidney injury (AKI). The differentiation between CKD vs AKI is often difficult and sometimes the both may coexist. A combined kidney-liver transplant (CKLT) may result in a kidney transplant in patients whose renal function is likely to recover or at least who have stable renal function post-transplant. We retrospectively enrolled 2742 patients who underwent living donor liver transplant at our center from 2007 to 2019.

METHODS

This audit was carried out in liver transplant recipients with CKD 3 to 5 who underwent either liver transplant alone (LTA) or CKLT to look at outcomes and long-term evolution of renal function. Forty-seven patients met the medical eligibility criteria for CKLT. Of the 47 patients, 25 underwent LTA and the rest 22 underwent CKLT. The diagnosis of CKD was made according to the Kidney Disease: Improving Global Outcomes classification.

RESULTS

Preoperative renal function parameters were comparable between the 2 groups. However, CKLT patients had significantly lower glomerular filtration rates (P = .007) and higher proteinuria (P = .01). Postoperatively, renal function, and comorbidities were comparable between the 2 groups. Survival was similar at 1, 3, and 12 months, respectively (log-rank; P = .84, = .81, and = .96, respectively). At the end of the study period, 57% of patients who survived in LTA groups had stabilized renal function (Creatinine = 1.8 ± 0.6 mg/dL).

CONCLUSIONS

Liver transplant alone is not inferior to CKLT in living donor situations. Renal dysfunction is stabilized in the long term whereas long-term dialysis may be carried out in others. Living donor liver transplantation alone is not inferior to CKLT for cirrhotic patients with CKD.

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

Outcomes from simultaneous liver-kidney transplantation (SLKT) when using kidneys from donors with acute kidney injury (AKI) have not been studied. We studied 5344 SLKTs between May 1, 2007, and December 31, 2019, by using Organ Procurement and Transplantation Network registry data supplemented with United Network for Organ Sharing-DonorNet data. Designating a donor as having AKI required by definition that the following criteria were met: (1) the donor's condition aligned with the Kidney Disease: Improving Global Outcomes (KDIGO) international consensus guidelines and the terminal serum creatinine (Scr) level was ≥1.5 times the minimum Scr level for deceased donors before organ recovery and (2) the terminal Scr level was ≥1.5 mg/dL (a clinically meaningful and intuitive Scr threshold for defining AKI for transplant providers). The primary outcomes were liver transplant all-cause graft failure (ACGF; defined as graft failures and deaths) and kidney transplant death-censored graft failure (DCGF) at 1 year after transplant. The donors with AKI were young, had good organ quality, and had a short cold ischemia time. In the study cohort, 4482 donors had no AKI, whereas 862 had AKI (KDIGO AKI stages: 1, n = 521; 2, n = 202; and 3, n = 138). In the group with AKI and the group with no AKI, respectively, liver ACGF at 1 year (11.1% versus 12.9% [P = 0.13]; hazard ratio [HR], 1.20; 95% confidence interval [CI], 0.97-1.49) and kidney DCGF at 1 year (4.6% versus 5.7% [P = 0.18]; HR, 1.27; 95% CI, 0.95-1.70) did not differ in the full multivariable Cox proportional hazard models. Selected kidneys from deceased donors with AKI can be considered for SLKT.

Utilization and effectiveness of the organ procurement and transplantation network "safety-net" policy

BACKGROUND

Liver transplant recipients with persistent renal dysfunction may be prioritized on the kidney transplant waitlist based on the Organ Procurement and Transplantation Network "safety-net" policy implemented in 2017. The aim of this study was to evaluate the utilization of kidney transplant and posttransplant outcomes, of liver transplant recipients with persistent renal dysfunction before and after implementation of the Organ Procurement and Transplantation Network kidney safety-net policy and standardization of simultaneous liver-kidney requirements.

METHODS

Using the United Network for Organ Sharing database from January 2015 to March 2019, outcomes of liver transplant recipients listed for kidney transplant and the subset who received kidney after liver transplants were compared before and after policy implementation.

RESULTS

Liver transplant recipients listed for kidney transplant increased from 58 to 200, and kidney after liver transplants increased from 29.3% to 42.5% after safety-net policy implementation. Post-policy kidney after liver transplants received more local organs (91.8% vs 70.6%, P = .03) and trended toward shorter waitlist time (47 [17-123] vs 84 [37-226] days, P = .051). The pre- and post-policy cohorts had similar (P > .05) kidney donor profile index (0.43 [0.27-0.69] vs 0.42 [0.28-0.58]) and delayed graft function (11.8% vs 14.1%). Patient, kidney graft, and liver graft survival were similar (P > .05) between pre and post-policy cohorts. Patient and kidney graft survival were similar between kidney after liver transplants and propensity score-matched kidney transplant alone recipients. Patient, kidney, and liver graft survival were similar between kidney after liver transplants and propensity score-matched simultaneous liver-kidney transplant recipients.

CONCLUSION

This study demonstrates that after Organ Procurement and Transplantation Network "safety-net" policy implementation, there has been an increase in liver transplant recipients with renal dysfunction who are listed for and undergo kidney transplant with excellent short-term results.

Kidney Disease After Nonkidney Solid Organ Transplant

Nonkidney solid organ transplants (NKSOTs) are increasing in the United States with improving long-term allograft and patient survival. CKD is prevalent in patients with NKSOT and is associated with increased morbidity and mortality especially in those who progress to end-stage kidney disease. Calcineurin inhibitor nephrotoxicity is a main contributor to CKD after NKSOT, but other factors in the pretransplant, peritransplant, and post-transplant period can predispose to progressive kidney dysfunction. The management of CKD after NKSOT generally follows society guidelines for native kidney disease. Kidney-protective and calcineurin inhibitor-sparing immunosuppression has been explored in this population and warrants a discussion with transplant teams. Kidney transplantation in NKSOT recipients remains the kidney replacement therapy of choice for suitable candidates, as it provides a survival benefit over remaining on dialysis.

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.

First World Consensus Conference on pancreas transplantation: Part II - recommendations

The First World Consensus Conference on Pancreas Transplantation provided 49 jury deliberations regarding the impact of pancreas transplantation on the treatment of diabetic patients, and 110 experts' recommendations for the practice of pancreas transplantation. The main message from this consensus conference is that both simultaneous pancreas-kidney transplantation (SPK) and pancreas transplantation alone can improve long-term patient survival, and all types of pancreas transplantation dramatically improve the quality of life of recipients. Pancreas transplantation may also improve the course of chronic complications of diabetes, depending on their severity. Therefore, the advantages of pancreas transplantation appear to clearly surpass potential disadvantages. Pancreas after kidney transplantation increases the risk of mortality only in the early period after transplantation, but is associated with improved life expectancy thereafter. Additionally, preemptive SPK, when compared to SPK performed in patients undergoing dialysis, appears to be associated with improved outcomes. Time on dialysis has negative prognostic implications in SPK recipients. Increased long-term survival, improvement in the course of diabetic complications, and amelioration of quality of life justify preferential allocation of kidney grafts to SPK recipients. Audience discussions and live voting are available online at the following URL address: http://mediaeventi.unipi.it/category/1st-world-consensus-conference-of-pancreas-transplantation/246.

The Impact of the 2017 Kidney Allocation Policy Change on Simultaneous Liver-Kidney Utilization and Outcomes

Historically in the United States, kidneys for simultaneous liver-kidney transplantation (SLKT) candidates were allocated with livers, prioritizing SLKT recipients over much of the kidney waiting list. A 2017 change in policy delineated renal function criteria for SLKT and implemented a safety net for kidney-after-liver transplantation. We compared the use and outcomes of SLKT and kidney-after-liver transplant with the 2017 policy. United Network for Organ Sharing Standard Transplant Analysis and Research files were used to identify adults who received liver transplantations (LT) from August 10, 2007 to August 10, 2012; from August 11, 2012 to August 10, 2017; and from August 11, 2017 to June 12, 2019. LT recipients with end-stage renal disease (ESRD) were defined by dialysis requirement or estimated glomerular filtration rate <25. We evaluated outcomes and center-level, regional, and national practice before and after the policy change. Nonparametric cumulative incidence of kidney-after-liver listing and transplant were modeled by era. A total of 6332 patients received SLKTs during the study period; fewer patients with glomerular filtration rate (GFR) ≥50 mL/min underwent SLKT over time (5.8%, 4.8%, 3.0%; P = 0.01 ). There was also less variability in GFR at transplant after policy implementation on center and regional levels. We then evaluated LT-alone (LTA) recipients with ESRD (n = 5408 from 2012-2017; n = 2321 after the policy). Listing for a kidney within a year of LT increased from 2.9% before the policy change to 8.8% after the policy change, and the rate of kidney transplantation within 1 year increased from 0.7% to 4% (P < 0.001). After the policy change, there was no difference in patient survival rates between SLKT and LTA among patients with ESRD. Implementation of the 2017 SLKT policy change resulted in reduced variability in SLKT recipient kidney function and increased access to deceased donor kidney transplantation for LTA recipients with kidney disease without negatively affecting outcomes.

Advances in management of hepatorenal syndrome

PURPOSE OF REVIEW

Hepatorenal syndrome (HRS) is encountered frequently in patients with end-stage liver disease and remains an important cause of morbidity and mortality in this patient population. This review will focus and provide updates on pathophysiology, assessment of kidney function, new definitions, and treatment and prevention of HRS.

RECENT FINDINGS

Pathophysiology of HRS has been elucidated more recently and in addition to hemodynamic changes, the role of systemic inflammatory response contributes significantly to this process. Assessment of kidney function in patients with liver cirrhosis remains challenging. Novel glomerular filtration rate equations have been developed in patients with liver disease to better estimate kidney function and changes made in the definition of acute kidney injury (AKI), which are more aligned with KDIGO criteria for AKI. Vasoconstrictors, especially terlipressin, along with albumin remain the mainstay of pharmacological treatment of HRS-AKI. Biomarkers have been useful in differentiating ATN from HRS at an early stage.

SUMMARY

HRS remains a significant cause of morbidity and mortality for patients with end-stage liver disease. Newer understanding of mechanisms in development and pathophysiology of HRS have helped with elucidation of the disease process.

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.

The impact of multi-organ transplant allocation priority on waitlisted kidney transplant candidates

Kidney-alone transplant (KAT) candidates may be disadvantaged by the allocation priority given to multi-organ transplant (MOT) candidates. This study identified potential KAT candidates not receiving a given kidney offer due to its allocation for MOT. Using the Organ Procurement and Transplant Network (OPTN) database, we identified deceased donors from 2002 to 2017 who had one kidney allocated for MOT and the other kidney allocated for KAT or simultaneous pancreas-kidney transplant (SPK) (n = 7,378). Potential transplant recipient data were used to identify the "next-sequential KAT candidate" who would have received a given kidney offer had it not been allocated to a higher prioritized MOT candidate. In this analysis, next-sequential KAT candidates were younger (p < .001), more likely to be racial/ethnic minorities (p < .001), and more highly sensitized than MOT recipients (p < .001). A total of 2,113 (28.6%) next-sequential KAT candidates subsequently either died or were removed from the waiting list without receiving a transplant. In a multivariable model, despite adjacent position on the kidney match-run, mortality risk was significantly higher for next-sequential KAT candidates compared to KAT/SPK recipients (hazard ratio 1.55, 95% confidence interval 1.44, 1.66). These results highlight implications of MOT allocation prioritization, and potential consequences to KAT candidates prioritized below MOT candidates.

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.

Defining a Willingness-to-transplant Threshold in an Era of Organ Scarcity: Simultaneous Liver-kidney Transplant as a Case Example

BACKGROUND

Organ scarcity continues in solid organ transplantation, such that the availability of organs limits the number of people able to benefit from transplantation. Medical advancements in managing end-stage organ disease have led to an increasing demand for multiorgan transplant, wherein a patient with multiorgan disease receives >1 organ from the same donor. Current allocation schemes give priority to multiorgan recipients compared with single-organ transplant recipients, which raise ethical questions regarding equity and utility.

METHODS

We use simultaneous liver and kidney (SLK) transplant, a type of multiorgan transplant, as a case study to examine the tension between equity and utility in multiorgan allocation. We adapt the health economics willingness-to-pay threshold to a solid organ transplant setting by coining a new metric: the willingness-to-transplant (WTT) threshold.

RESULTS

We demonstrate how the WTT threshold can be used to evaluate different SLK allocation strategies by synthesizing utility and equity perspectives.

CONCLUSIONS

We submit that this new framework enables us to distill the question of SLK allocation down to: what is the minimum amount of benefit we require from a deceased donor kidney to allocate it for a particular indication? Addressing the above question will prove helpful to devising a rational system of SLK allocation and is applicable to other transplant settings.

Outcomes of liver-kidney transplantation in patients with primary hyperoxaluria: an analysis of the scientific registry of transplant recipients database

Background

Primary hyperoxaluria (PH) is an inherited disease lacking of hepatic oxalic acid metabolic enzymes which could lead to irreverisible renal damage. Currently, liver–kidney transplantation is a curative but highly invasive therapy used to treat patients with PH. However, limited studies have focused on combined liver–kidney transplantation (CLKT) and sequential liver and kidney transplantation (SLKT) in patients with PH.

Methods

The present study included 201 patients with PH who received both liver and kidney transplants and who were listed on the Scientific Registry of Transplant Recipients from 1987 to 2018. According to the liver–kidney transplant procedure, patients were separated into a CLKT group and a SLKT group. Patient demographics and transplant outcomes were assessed in each group.

Results

Compared with the SLKT group, The CLKT group got a worse pretransplant dialysis condition in both the proportion of patients under pretransplant dialysis (p = 0.048) and the duration of the pretransplant dialysis (p < 0.001). The SLKT group got higher human leukocyte antigen mismatch score of kidney donor (p < 0.001) and liver donor (p = 0.003). The CLKT group utilized higher proportion (98.9%) of organs from a single deceased donor, while the SLKT group utilized 75.0% of organs from deceased liver donors and only 35.0% of organs from deceased kidney donors (p < 0.001). Kidney function measured by serum creatinine concentration before liver transplantation (LT) or CLKT was similar (p = 0.305) between groups. Patient survival was not significantly different between the two groups (p = 0.717) and liver (p = 0.685) and kidney (p = 0.464) graft outcomes were comparable between the two groups.

Conclusions

SLKT seems to be an alternative option with strict condition for CLKT, further exploration about the SLKT is still required.

To kidney or not to kidney: Applying lessons learned from the simultaneous liver-kidney transplant policy to simultaneous heart-kidney transplantation

As the medical community is increasingly offering transplantation to patients with increasing comorbidity burdens, the number of simultaneous heart-kidney (SHK) transplants is rising in the United States. How to determine eligibility for SHK transplant versus heart transplant alone is unknown. In this review, we situate this problem in the broader picture of organ shortage. We critically appraise available literature on outcomes in SHK versus heart transplant alone. We posit staged kidney-after-heart transplantation as a plausible alternative to SHK transplantation and review the pros and cons. Drawing lessons from the field of simultaneous liver-kidney transplant, we argue for an analogous policy for SHK transplant with standardized minimal eligibility criteria and a modified Safety Net provision. The new policy will serve as a starting point for comparing simultaneous versus staged approaches and refining the medical eligibility criteria for SHK.

Outcomes of Liver Transplantation in Patients on Renal Replacement Therapy: Considerations for Simultaneous Liver Kidney Transplantation Versus Safety Net

As the liver transplant (LT) waiting list continues to outpace organ availability, many patients require renal replacement therapy (RRT) before LT. It is unclear which patients will benefit from simultaneous liver kidney (SLK) transplant as opposed to awaiting a Safety Net kidney transplant (KT) post-LT.

Methods

In this study, a retrospective analysis of the United Network for Organ Sharing dataset was performed to identify risk factors associated with poor outcome for patients on RRT before LT who were listed for SLK and received either SLK vs LT alone (LTA).

Results

Between January 2003 and December 2016, 8971 adult LT recipients were on RRT at the time of LT. 5359 were listed for and received LTA (Group 1). Of 3612 patients listed for SLK, 3414 (38.1%) received SLK (Group 2) and 198 (2.2%) received LTA (Group 3). Overall, Group 3 had lower graft and patient survival post-LT when compared with Groups 1 and 2 (P < 0.001). Serum creatinine at 1 year post-LT and cumulative incidence for KT at 3 years post-LT were higher for Group 3 (P < 0.001). On multivariate analysis, pre-LT diabetes (P = 0.002), Model of End-Stage Liver Disease score (P = 0.01), and donor kidney donor profile index (P = 0.025) were significant in Group 2. Recipient age >60 (P < 0.001) and RRT pre-LT (>90 days; P = 0.001) were associated with lower patient survival in Group 3.

Conclusions

Among LT recipients on RRT before LT who were listed for SLK, RRT >90 days, and age >60 were associated with poor outcome following LTA. This suggests that programs should carefully weigh the decision to proceed with LTA vs waiting for SLK in this patient population. Future access to Safety Net KT will be an important consideration for these patients moving forward.

Assessing the outcome of organ allocation: choosing metrics

PURPOSE OF REVIEW

Organ allocation is a highly complex process with significant impact on outcomes of donor organs and end-stage organ disease patients. Policies governing allocation must incorporate numerous factors to meet stated objective. There have been significant alterations and ongoing discussion about changes in allocation policy for all solid organs in the United States. As with any policy change, rigorous evaluation of the impact of changes is important.

RECENT FINDINGS

This manuscript discusses metrics to consider to evaluate the impact of organ allocation policy that may be monitored on an ongoing basis including examples of research evaluating current policies. Potential metrics to evaluate allocation policy include the effectiveness, efficiency, equity, costs, donor rates, and transparency associated with the system.

SUMMARY

Ultimately, policies will often need to adapt to secular changes in donor and patient characteristics, clinical and technological advances, and overarching healthcare polices. Providing objective empirical evaluation of the impact of policies is a critical component for assessing quality of the allocation system and informing the effect of changes. The foundation of organ transplantation is built upon public trust and the dependence on the gift of donor organs, as such the importance of the most appropriate organ allocation policies cannot be overstated.

Hepatorenal Syndrome

Hepatorenal syndrome is a severe complication of end-stage cirrhosis characterized by increased splanchnic blood flow, hyperdynamic state, a state of decreased central volume, activation of vasoconstrictor systems, and extreme kidney vasoconstriction leading to decreased GFR. The contribution of systemic inflammation, a key feature of cirrhosis, in the development of hepatorenal syndrome has been highlighted in recent years. The mechanisms by which systemic inflammation precipitates kidney circulatory changes during hepatorenal syndrome need to be clarified. Early diagnosis is central in the management and recent changes in the definition of hepatorenal syndrome help identify patients at an earlier stage. Vasoconstrictive agents (terlipressin in particular) and albumin are the first-line treatment option. Several controlled studies proved that terlipressin is effective at reversing hepatorenal syndrome and may improve short-term survival. Not all patients are responders, and even in responders, early mortality rates are very high in the absence of liver transplantation. Liver transplantation is the only curative treatment of hepatorenal syndrome. In the long term, patients transplanted with hepatorenal syndrome tend to have lower GFR compared with patients without hepatorenal syndrome. Differentiating hepatorenal syndrome from acute tubular necrosis (ATN) is often a challenging yet important step because vasoconstrictors are not justified for the treatment of ATN. Hepatorenal syndrome and ATN may be considered as a continuum rather than distinct entities. Emerging biomarkers may help differentiate these two conditions and provide prognostic information on kidney recovery after liver transplantation, and potentially affect the decision for simultaneous liver-kidney transplantation.

Incidence and Impact of Acute Kidney Injury after Liver Transplantation: A Meta-Analysis

Background: The study’s aim was to summarize the incidence and impacts of post-liver transplant (LTx) acute kidney injury (AKI) on outcomes after LTx. Methods: A literature search was performed using the MEDLINE, EMBASE and Cochrane Databases from inception until December 2018 to identify studies assessing the incidence of AKI (using a standard AKI definition) in adult patients undergoing LTx. Effect estimates from the individual studies were derived and consolidated utilizing random-effect, the generic inverse variance approach of DerSimonian and Laird. The protocol for this systematic review is registered with PROSPERO (no. CRD42018100664). Results: Thirty-eight cohort studies, with a total of 13,422 LTx patients, were enrolled. Overall, the pooled estimated incidence rates of post-LTx AKI and severe AKI requiring renal replacement therapy (RRT) were 40.7% (95% CI: 35.4%–46.2%) and 7.7% (95% CI: 5.1%–11.4%), respectively. Meta-regression showed that the year of study did not significantly affect the incidence of post-LTx AKI (p = 0.81). The pooled estimated in-hospital or 30-day mortality, and 1-year mortality rates of patients with post-LTx AKI were 16.5% (95% CI: 10.8%–24.3%) and 31.1% (95% CI: 22.4%–41.5%), respectively. Post-LTx AKI and severe AKI requiring RRT were associated with significantly higher mortality with pooled ORs of 2.96 (95% CI: 2.32–3.77) and 8.15 (95%CI: 4.52–14.69), respectively. Compared to those without post-LTx AKI, recipients with post-LTx AKI had significantly increased risk of liver graft failure and chronic kidney disease with pooled ORs of 3.76 (95% CI: 1.56–9.03) and 2.35 (95% CI: 1.53–3.61), respectively. Conclusion: The overall estimated incidence rates of post-LTx AKI and severe AKI requiring RRT are 40.8% and 7.0%, respectively. There are significant associations of post-LTx AKI with increased mortality and graft failure after transplantation. Furthermore, the incidence of post-LTx AKI has remained stable over the ten years of the study.

Comparing Simultaneous Liver-Kidney Transplant Strategies: A Modified Cost-Effectiveness Analysis

BACKGROUND

The proportion of patients with kidney failure at time of liver transplantation is at a historic high in the United States. The optimal timing of kidney transplantation with respect to the liver transplant is unknown.

METHODS

We used a modified cost-effectiveness analysis to compare 4 strategies: the old system ("pre-OPTN"), the new Organ Procurement Transplant Network (OPTN) system since August 10, 2017 ("OPTN"), and 2 strategies which restrict simultaneous liver-kidney transplants ("safety net" and "stringent"). We measured "cost" by deployment of deceased donor kidneys (DDKs) to liver transplant recipients and effectiveness by life years (LYs) and quality-adjusted life years (QALYs) in liver transplant recipients. We validated our model against Scientific Registry for Transplant Recipients data.

RESULTS

The OPTN, safety net and stringent strategies were on the efficiency frontier. By rank order, OPTN > safety net > stringent strategy in terms of LY, QALY, and DDK deployment. The pre-OPTN system was dominated, or outperformed, by all alternative strategies. The incremental LY per DDK between the strategies ranged from 1.30 to 1.85. The incremental QALY per DDK ranged from 1.11 to 2.03.

CONCLUSIONS

These estimates quantify the "organ"-effectiveness of various kidney allocation strategies for liver transplant candidates. The OPTN system will likely deliver better liver transplant outcomes at the expense of more frequent deployment of DDKs to liver transplant recipients.

Refining the Role of Simultaneous Liver Kidney Transplantation

Adoption of the model for end-stage liver disease score by Organ Procurement and Transplant Network (OPTN) deceased donor liver allocation policy in 2002 has led to an increase in the number of simultaneous liver kidney (SLK) transplantation. Since kidney function recovery following liver transplantation is difficult to predict, allocation of the kidney for SLK transplantation thus far has not been based on much rationale and evidence. Lack of OPTN policy towards SLK organ allocation has resulted in great variations among transplant centers regarding SLK transplantation. Increasing use of kidneys towards SLK transplantation diverts deceased donor kidneys away from candidates awaiting kidney-alone transplantation. Recently OPTN/United Network of Organ Sharing has implemented medical eligibility criteria for adult SLK transplantation which also includes a concept of safety net. Implementation of the new policy is a move in a positive direction, providing consistency in our practice and evidence-based guidelines in selecting candidates for SLK transplantation. This policy needs to be monitored prospectively and modified based on new data that will emerge over time. This review outlines the literature on SLK transplantation and efforts towards developing rational policy on SLK organ allocation.

Simultaneous Liver-Kidney Transplantation: Impact on Liver Transplant Patients and the Kidney Transplant Waiting List

Purpose

The number of simultaneous liver-kidney transplants (SLKT) performed in the USA has been rising. The Organ Procurement and Transplantation Network implemented a new policy governing SLKT that specifies eligibility criteria for candidates to receive a kidney with a liver, and creates a kidney waitlist “safety net” for liver recipients with persistent renal failure after transplant. This review explores potential impacts for liver patients and the kidney waitlist.

Recent Findings

Factors that have contributed to the rise in SLKT including Model for End-stage Liver Disease (MELD)-based allocation, regional sharing for high MELD candidates, and the rising incidence of non-alcoholic steatohepatitis will continue to increase the number of liver transplant candidates with concurrent renal insufficiency. The effect of center behavior based on the new policy is harder to predict, given wide historic variability in SLKT practice.

Summary

Continued increase in combined liver/kidney failure is likely, and SLKT and kidney after liver transplant may both increase. Impact of the new policy should be carefully monitored, but influences beyond the policy need to be accounted for.

The donor risk index: A decade of experience

In 2006, derivation of the donor risk index (DRI) highlighted the importance of donor factors for successful liver transplantation. Over the last decade, the DRI has served as a useful metric of donor quality and has enhanced our understanding of donor factors and their impact upon recipients with hepatitis C virus, those with low Model for End-Stage Liver Disease (MELD) score, and individuals undergoing retransplantation. DRI has provided the transplant community with a common language for describing donor organ characteristics and has served as the foundation for several tools for organ risk assessment. It is a useful tool in assessing the interactions of donor factors with recipient factors and their impact on posttransplant outcomes. However, limitations of statistical modeling, choice of donor factors, exclusion of unaccounted donor and geographic factors, and the changing face of the liver transplant recipient have tempered its widespread use. In addition, the DRI was derived from data before the MELD era but is currently being applied to expand the donor pool while concurrently meeting the demands of a dynamic allocation system. A decade after its introduction, DRI remains relevant but may benefit from being updated to provide guidance in the use of extended criteria donors by accounting for the impact of geography and unmeasured donor characteristics. DRI could be better adapted for recipients with nonalcoholic fatty liver disease by examining and including recipient factors unique to this population. Liver Transplantation 23 1216-1225 2017 AASLD.