Liver transplant allocation policies and outcomes in United States: A comprehensive review

Role of Liver Transplant in Primary and Secondary Liver Malignancies

Hepatocellular carcinoma (HCC) and cholangiocarcinoma are the primary hepatic malignancies with established pathways to transplantation and model for end-stage liver disease (MELD) exception points. Other tumors managed with liver transplantation (LT) include hepatic epithelioid hemangioendothelioma and fibrolamellar HCC. LT for metastatic neuroendocrine tumor has been established with patient selection criteria and a path to MELD exception points. Additionally, recent data on LT for patients with unresectable hepatic colorectal metastases demonstrate increasingly encouraging initial results.

The impact of normothermic machine perfusion and acuity circles on waitlist time, mortality, and cost in liver transplantation: A multicenter experience

Ex situ normothermic machine perfusion (NMP) helps increase the use of extended criteria donor livers. However, the impact of an NMP program on waitlist times and mortality has not been evaluated. Adult patients listed for liver transplant (LT) at 2 academic centers from January 1, 2015, to September 1, 2023, were included (n=2773) to allow all patients ≥6 months follow-up from listing. Routine NMP was implemented on October 14, 2022. Waitlist outcomes were compared from pre-NMP pre-acuity circles (n=1460), pre-NMP with acuity circles (n=842), and with NMP (n=381). Median waitlist time was 79 days (IQR: 20-232 d) at baseline, 49 days (7-182) with acuity circles, and 14 days (5-56) with NMP ( p <0.001). The rate of transplant-per-100-person-years improved from 61-per-100-person-years to 99-per-100-person-years with acuity circles and 194-per-100-person-years with NMP ( p <0.001). Crude mortality without transplant decreased from 18.3% (n=268/1460) to 13.3% (n=112/843), to 6.3% (n=24/381) ( p <0.001) with NMP. The incidence of mortality without LT was 15-per-100-person-years before acuity circles, 19-per-100 with acuity circles, and 9-per-100-person-years after NMP ( p <0.001). Median Model for End-Stage Liver Disease at LT was lowest with NMP, but Model for End-Stage Liver Disease at listing was highest in this era ( p <0.0001). The median donor risk index of transplanted livers at baseline was 1.54 (1.27-1.82), 1.66 (1.42-2.16) with acuity circles, and 2.06 (1.63-2.46) with NMP ( p <0.001). Six-month post-LT survival was not different between eras ( p =0.322). The total cost of health care while waitlisted was lowest in the NMP era ($53,683 vs. $32,687 vs. $23,688, p <0.001); cost-per-day did not differ between eras ( p =0.152). The implementation of a routine NMP program was associated with reduced waitlist time and mortality without compromising short-term survival after liver transplant despite increased use of riskier grafts. Routine NMP use enables better waitlist management with reduced health care costs.

Surgical management of liver tumors

Two percent of pediatric malignancies arise primarily in the liver; roughly 60% of these cancers are hepatoblastoma (HB). Despite the rarity of these cases, international collaborative efforts have led to the consistent histological classification and staging systems, which facilitate ongoing clinical trials. Other primary liver malignancies seen in children include hepatocellular carcinoma (HCC) with or without underlying liver disease, fibrolamellar carcinoma (FLC), undifferentiated embryonal sarcoma of the liver (UESL), and hepatocellular neoplasm not otherwise specified (HCN-NOS). This review describes principles of surgical management of malignant pediatric primary liver tumors, within the context of comprehensive multidisciplinary care.

Lesson learnt from 60 years of liver transplantation: Advancements, challenges, and future directions

Over the past six decades, liver transplantation (LT) has evolved from an experimental procedure into a standardized and life-saving intervention, reshaping the landscape of organ transplantation. Driven by pioneering breakthroughs, technological advancements, and a deepened understanding of immunology, LT has seen remarkable progress. Some of the most notable breakthroughs in the field include advances in immunosuppression, a revised model for end-stage liver disease, and artificial intelligence (AI)-integrated imaging modalities serving diagnostic and therapeutic roles in LT, paired with ever-evolving technological advances. Additionally, the refinement of transplantation procedures, resulting in the introduction of alternative transplantation methods, such as living donor LT, split LT, and the use of marginal grafts, has addressed the challenge of organ shortage. Moreover, precision medicine, guiding personalized immunosuppressive strategies, has significantly improved patient and graft survival rates while addressing emergent issues, such as short-term complications and early allograft dysfunction, leading to a more refined strategy and enhanced post-operative recovery. Looking ahead, ongoing research explores regenerative medicine, diagnostic tools, and AI to optimize organ allocation and post-transplantation car. In summary, the past six decades have marked a transformative journey in LT with a commitment to advancing science, medicine, and patient-centered care, offering hope and extending life to individuals worldwide.

Finding Value in Pediatric Liver Transplantation: When Does Volume Matter?

INTRODUCTION

Pediatric liver transplantation provides substantial survival benefit. An emphasis on value-based practices has become a central theme in many surgical fields, but have not been well-studied in pediatric transplantation. Given an increasing focus on optimizing outcomes while containing costs, defining value in pediatric liver transplantation warrants investigation.

METHODS

Pediatric end-stage liver disease -era deceased donor pediatric liver transplant recipients from 2/2002 to 2/2019 were identified using the United Network for Organ Sharing Standard Transplant Analysis file data (n = 5770). Liver centers were divided into volume tertiles (small, medium, and large), and recipients were stratified by age (0-4, 5-11, and 12-18 y). The value for the index transplant episode was defined as % graft survival ≥1 y divided by mean post-transplant length of stay. Nearest-neighbor Mahalanobis metric matching was used to account for confounding when assessing the impact of center volume on value.

RESULTS

Compared to small centers, large centers delivered better outcomes (1-y graft survival 93.7% versus 89.4%, P = 0.017) without increased resource utilization (length of stay 20.8 ± 15.6 d versus 19.6 ± 17.0, P = 0.281) during the 17-y study period. Mahalanobois-matched cohorts demonstrated a volume-value relationship (higher value care with better outcomes and decreased resource utilization) in the 0-4 age group, but not in older recipients. The 0-4 age group comprised the largest proportion of status 1B patients (21.8%, P < 0.001) and the highest utilization rate of partial liver allografts (40.9%, P < 0.001).

CONCLUSIONS

There is value in liver transplant volume in very young (0-4 y) deceased donor pediatric patients. Given improved survival of these patients in higher volume centers, regionalization of care may benefit this specific population of recipients.

Inconsistent values and algorithmic fairness: a review of organ allocation priority systems in the United States

BACKGROUND

The Organ Procurement and Transplant Network (OPTN) Final Rule guides national organ transplantation policies, mandating equitable organ allocation and organ-specific priority stratification systems. Current allocation scores rely on mortality predictions.

METHODS

We examined the alignment between the ethical priorities across organ prioritization systems and the statistical design of the risk models in question. We searched PubMed for literature on organ allocation history, policy, and ethics in the United States.

RESULTS

We identified 127 relevant articles, covering kidney (19), liver (60), lung (24), and heart transplants (23), and transplant accessibility (1). Current risk scores emphasize model performance and overlook ethical concerns in variable selection. The inclusion of race, sex, and geographical limits as categorical variables lacks biological basis; therefore, blurring the line between evidence-based models and discrimination. Comprehensive ethical and equity evaluation of risk scores is lacking, with only limited discussion of the algorithmic fairness of the Model for End-Stage Liver Disease (MELD) and the Kidney Donor Risk Index (KDRI) in some literature. We uncovered the inconsistent ethical standards underlying organ allocation scores in the United States. Specifically, we highlighted the exception points in MELD, the inclusion of race in KDRI, the geographical limit in the Lung Allocation Score, and the inadequacy of risk stratification in the Heart Tier system, creating obstacles for medically underserved populations.

CONCLUSIONS

We encourage efforts to address statistical and ethical concerns in organ allocation models and urge standardization and transparency in policy development to ensure fairness, equitability, and evidence-based risk predictions.

Surgical Implications for Nonalcoholic Steatohepatitis-Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is an aggressive form of liver cancer that arises in a background of chronic hepatic injury. Metabolic syndrome-associated fatty liver disease (MAFLD) and its severe form, nonalcoholic steatohepatitis (NASH), are increasingly common mechanisms for new HCC cases. NASH-HCC patients are frequently obese and medically complex, posing challenges for clinical management. In this review, we discuss NASH-specific challenges and the associated implications, including benefits of minimally invasive operative approaches in obese patients; the value of y90 as a locoregional therapy; and the roles of weight loss and immunotherapy in disease management. The relevant literature was identified through queries of PubMed, Google Scholar, and clinicaltrials.gov. Provider understanding of clinical nuances specific to NASH-HCC can improve treatment strategy and patient outcomes.

Pre-transplant Loco-Regional Therapy for Hepatocellular Carcinoma and Post-transplant Outcomes: A National Study

The ultimate preferred treatment for hepatocellular carcinoma (HCC) complicated with cirrhosis and portal hypertension is an orthotopic liver transplant (OLT). Loco regional therapy (LRT) has emerged to prevent tumor growth and progression of disease beyond the Milan criteria to achieve transplant. There is a paucity of data regarding safety, posttransplant survival benefits, and tumor recurrence rate achieved by these LRT modalities. We aim to assess and compare the five-year survival rate and tumor recurrence rate with or without LRT in patients after OLT with diagnosed HCC utilizing the nation's largest dataset. This is a retrospective observational study approved by Saint Louis University institutional review board. We utilized the largest dataset from the years 2003-2013 where pertaining data were gathered from Organ Procurement Transplant Network (OPTN) standard analysis and research files (STAR) through novel linkages with Medicare bills. Descriptive and comparative statistics were performed. 2412 (51.6%) patients received any form of locoregional therapy (single or combination) out of 4669 total study sample size. The overall five-year survival in the study sample was 76.1%. There was statistically no significant improvement seen in five-year posttransplant survival in the group that received one mode of LRT (adjusted hazard ratio (aHR) 0.97, P<0.64) or a combination of LRT (aHR 0.94, P<0.58) in comparison to those that received none after adjusting donor and recipient clinical characteristics. However, five-year survival trended higher among those treated with combination therapy over those treated with single LRT or none. Overall HCC recurrence was 4.8%, while no significant difference was noted when comparing above-mentioned groups. Five-year posttransplant survival and HCC recurrence rate were also found to have no difference when compared between above-mentioned groups after adjusting explant pathology. This is the largest retrospective study comparing liver transplant patients with HCC who received LRT to none. Although it did not show any statistically significant benefit of single or combination of LRT on survival or tumor recurrence after liver transplant for HCC patients, the outcomes encourage the safe and feasible use of LRT as a bridging therapy. Our study also suggests an observed pattern of improved posttransplant survival and tumor recurrence rate with combination loco-regional therapy. Larger multicenter prospective studies will be required to achieve the effect size to determine the best therapies for maximizing patient survival cost-effectively.

The impact of macro- and micro-steatosis on the outcomes of patients who undergo liver transplant: Analysis of the UNOS-STAR database

BACKGROUND AND AIMS

The presence of steatosis in a donor liver and its relation to post-transplantation outcomes are not well defined. This study evaluates the effect of the presence and severity of micro- and macro-steatosis of a donor graft on post-transplantation outcomes.

METHODS

The UNOS-STAR registry (2005-2019) was used to select patients who received a liver transplant graft with hepatic steatosis. The study cohort was stratified by the presence of macro- or micro-vesicular steatosis, and further stratified by histologic grade of steatosis. The primary endpoints of all-cause mortality and graft failure were compared using sequential Cox regression analysis. Analysis of specific causes of mortality was further performed.

RESULTS

There were 9184 with no macro-steatosis (control), 150 with grade 3 macro-steatosis, 822 with grade 2 macro-steatosis and 12 585 with grade 1 macro-steatosis. There were 10 320 without micro-steatosis (control), 478 with grade 3 micro-steatosis, 1539 with grade 2 micro-steatosis and 10 404 with grade 1 micro-steatosis. There was no significant difference in all-cause mortality or graft failure among recipients who received a donor organ with any evidence of macro- or micro-steatosis, compared to those receiving non-steatotic grafts. There was increased mortality due to cardiac arrest among recipients of a grade 2 macro-steatosis donor organ.

CONCLUSION

This study shows no significant difference in all-cause mortality or graft failure among recipients who received a donor liver with any degree of micro- or macro-steatosis. Further analysis identified increased mortality due to specific aetiologies among recipients receiving donor organs with varying grades of macro- and micro-steatosis.

Waitlist Outcomes for Exception and Non-exception Liver Transplant Candidates in the United States Following Implementation of the Median MELD at Transplant (MMaT)/250-mile Policy

BACKGROUND

Since February 2020, exception points have been allocated equivalent to the median model for end-stage liver disease at transplant within 250 nautical miles of the transplant center (MMaT/250). We compared transplant rate and waitlist mortality for hepatocellular carcinoma (HCC) exception, non-HCC exception, and non-exception candidates to determine whether MMaT/250 advantages (or disadvantages) exception candidates.

METHODS

Using Scientific Registry of Transplant Recipients data, we identified 23 686 adult, first-time, active, deceased donor liver transplant (DDLT) candidates between February 4, 2020, and February 3, 2022. We compared DDLT rates using Cox regression, and waitlist mortality/dropout using competing risks regression in non-exception versus HCC versus non-HCC candidates.

RESULTS

Within 24 mo of study entry, 58.4% of non-exception candidates received DDLT, compared with 57.8% for HCC candidates and 70.5% for non-HCC candidates. After adjustment, HCC candidates had 27% lower DDLT rate (adjusted hazard ratio =  0.68 0.73 0.77 ) compared with non-exception candidates. However, waitlist mortality for HCC was comparable to non-exception candidates (adjusted subhazard ratio [asHR] =  0.93 1.03 1.15 ). Non-HCC candidates with pulmonary complications of cirrhosis or cholangiocarcinoma had substantially higher risk of waitlist mortality compared with non-exception candidates (asHR =  1.27 1.70 2.29 for pulmonary complications of cirrhosis, 1.35 2.04 3.07 for cholangiocarcinoma). The same was not true of non-HCC candidates with exceptions for other reasons (asHR =  0.54 0.88 1.44 ).

CONCLUSIONS

Under MMaT/250, HCC, and non-exception candidates have comparable risks of dying before receiving liver transplant, despite lower transplant rates for HCC. However, non-HCC candidates with pulmonary complications of cirrhosis or cholangiocarcinoma have substantially higher risk of dying before receiving liver transplant; these candidates may merit increased allocation priority.

BOMS: blockchain-enabled organ matching system

This work proposes a Blockchain-enabled Organ Matching System (BOMS) designed to manage the process of matching, storing, and sharing information. Biological factors are incorporated into matching and the cross-matching process is implemented into the smart contracts. Privacy is guaranteed by using patient-associated blockchain addresses, without transmitting or using patient personal records in the matching process. The matching algorithm implemented as a smart contract is verifiable by any party. Clinical records, process updates, and matching results are also stored on the blockchain, providing tamper-resistance of recipient's records and the recipients' waiting queue. The system also is capable of handling cases in which there is a donor without an immediate compatible recipient. The system is implemented on the Ethereum blockchain and several scenarios were tested. The performance of the proposed system is compared to other existing organ donation systems, and ours outperformed any existing organ matching system built on blockchain. BOMS is tested to ascertain its compatibility with public, private, and consortium blockchain networks, checks for security vulnerabilities and cross-matching efficiency. The implementation codes are available online.

Cold ischemia time in liver transplantation: An overview

The standard approach to organ preservation in liver transplantation is by static cold storage and the time between the cross-clamping of a graft in a donor and its reperfusion in the recipient is defined as cold ischemia time (CIT). This simple definition reveals a multifactorial time frame that depends on donor hepatectomy time, transit time, and recipient surgery time, and is one of the most important donor-related risk factors which may influence the graft and recipient's survival. Recently, the growing demand for the use of marginal liver grafts has prompted scientific exploration to analyze ischemia time factors and develop different organ preservation strategies. This review details the CIT definition and analyzes its different factors. It also explores the most recent strategies developed to implement each timestamp of CIT and to protect the graft from ischemic injury.

Portal vein arterialization in 25 liver transplant recipients: A Latin American single-center experience

BACKGROUND

Portal vein arterialization (PVA) has been used in liver transplantation (LT) to maximize oxygen delivery when arterial circulation is compromised or has been used as an alternative reperfusion technique for complex portal vein thrombosis (PVT). The effect of PVA on portal perfusion and primary graft dysfunction (PGD) has not been assessed.

AIM

To examine the outcomes of patients who required PVA in correlation with their LT procedure.

METHODS

All patients receiving PVA and LT at the Fundacion Santa Fe de Bogota between 2011 and 2022 were analyzed. To account for the time-sensitive effects of graft perfusion, patients were classified into two groups: prereperfusion (pre-PVA), if the arterioportal anastomosis was performed before graft revascularization, and postreperfusion (post-PVA), if PVA was performed afterward. The pre-PVA rationale contemplated poor portal hemodynamics, severe vascular steal, or PVT. Post-PVA was considered if graft hypoperfusion became evident. Conservative interventions were attempted before PVA.

RESULTS

A total of 25 cases were identified: 15 before and 10 after graft reperfusion. Pre-PVA patients were more affected by diabetes, decompensated cirrhosis, impaired portal vein (PV) hemodynamics, and PVT. PGD was less common after pre-PVA (20.0% vs 60.0%) (P = 0.041). Those who developed PGD had a smaller increase in PV velocity (25.00 cm/s vs 73.42 cm/s) (P = 0.036) and flow (1.31 L/min vs 3.34 L/min) (P = 0.136) after arterialization. Nine patients required PVA closure (median time: 62 d). Pre-PVA and non-PGD cases had better survival rates than their counterparts (56.09 months vs 22.77 months and 54.15 months vs 31.91 months, respectively).

CONCLUSION

This is the largest report presenting PVA in LT. Results suggest that pre-PVA provides better graft perfusion than post-PVA. Graft hyperperfusion could play a protective role against PGD.

Excess waitlist mortality among candidates for multivisceral liver-intestine transplant in acuity circle allocation

Candidates for multivisceral transplant (MVT) have experienced decreased access to transplant in recent years. Using Organ Procurement and Transplantation Network data, transplant and waiting list outcomes for MVT (ie, liver-intestine, liver-intestine-pancreas, and liver-intestine-kidney-pancreas) candidates listed between February 4, 2018, and February 3, 2022, were analyzed, including model for end-stage liver disease/pediatric end-stage liver disease and exception scores by era (before and after acuity circle [AC] implementation on February 4, 2020) and age group (pediatric and adult). Of 284 MVT waitlist registrations (45.6% pediatric), fewer had exception points at listing post-AC compared to pre-AC (10.0% vs 19.1%), and they were less likely to receive transplant (19.1% vs 35.9% at 90 days; 35.7% vs 57.2% at 1 year). Of 177 MVT recipients, exception points at transplant were more common post-AC compared to pre-AC (30.8% vs 20.2%). Postpolicy, adult MVT candidates were more likely to be removed due to death/too sick compared with liver-alone candidates (13.5% vs 5.6% at 90 days; 24.2% vs 9.8% at 1 year), whereas no excess waitlist mortality was observed among pediatric MVT candidates. Under current allocation policy, multivisceral candidates experience inferior waitlist outcomes compared with liver-alone candidates. Clarification of guidance around submission and approval of multivisceral exception requests may help improve their access to transplantation and achieve equity between multivisceral and liver-alone candidates on the liver transplant waiting list.

2023 Clinical Update in Liver Transplantation

Liver transplantation continues to provide life-saving treatment for patients with end-stage liver disease. Advances in the field of transplant anesthesia continue to support the care of more complex patients. The use of extracorporeal membrane oxygenation has been described in critical care settings and cardiac surgery but may be a valuable option for specific conditions for patients undergoing liver transplantation. Changes to the allocation process for liver grafts now focus on acuity circles to reduce regional disparities. As the number of life-saving transplant surgeries increases, so does the need for specialty knowledge in the anesthetic considerations of these procedures. The specialty of transplant anesthesia continues to grow and develop to meet the demands of complex patients and the increased number of transplants performed. Liver transplantation can be a resource-demanding procedure, and predicting the need for massive transfusion can aid in planning and preparing for significant blood loss.

Machine Learning for Short-Term Mortality in Acute Decompensation of Liver Cirrhosis: Better than MELD Score

Prediction of short-term mortality in patients with acute decompensation of liver cirrhosis could be improved. We aimed to develop and validate two machine learning (ML) models for predicting 28-day and 90-day mortality in patients hospitalized with acute decompensated liver cirrhosis. We trained two artificial neural network (ANN)-based ML models using a training sample of 165 out of 290 (56.9%) patients, and then tested their predictive performance against Model of End-stage Liver Disease-Sodium (MELD-Na) and MELD 3.0 scores using a different validation sample of 125 out of 290 (43.1%) patients. The area under the ROC curve (AUC) for predicting 28-day mortality for the ML model was 0.811 (95%CI: 0.714- 0.907; p < 0.001), while the AUC for the MELD-Na score was 0.577 (95%CI: 0.435-0.720; p = 0.226) and for MELD 3.0 was 0.600 (95%CI: 0.462-0.739; p = 0.117). The area under the ROC curve (AUC) for predicting 90-day mortality for the ML model was 0.839 (95%CI: 0.776- 0.884; p < 0.001), while the AUC for the MELD-Na score was 0.682 (95%CI: 0.575-0.790; p = 0.002) and for MELD 3.0 was 0.703 (95%CI: 0.590-0.816; p < 0.001). Our study demonstrates that ML-based models for predicting short-term mortality in patients with acute decompensation of liver cirrhosis perform significantly better than MELD-Na and MELD 3.0 scores in a validation cohort.

Implementation of a National Liver Review Board for exception requests in the United States: A 2-year monitoring report

The exception point system for liver allocation in the United States allows for additional waitlist priority for candidates where the Model for End-Stage Liver Disease or Pediatric End-stage Liver Disease does not effectively represent their urgency or need for a transplant. In May 2019, the review process for liver exception cases transitioned from 11 Regional Review Boards (RRBs) to 1 National Liver Review Board (NLRB), intended to increase consistency nationwide, improve efficiency, and balance transplant access for candidates with and without exception scores. This report provides a review of liver exception request and review practices, waitlist outcomes, and transplant activity in the first 2 years after implementation of the NLRB and acuity circle-based distribution in the United States. We compared initial and extension exception request forms submitted from May 13, 2017 to May 13, 2019 (prepolicy or RRB era) to the period from February 4, 2020 to February 3, 2022 (postpolicy or NLRB era). During this time, the NLRB reviewed 10,083 initial exception requests and 12,686 extension requests. Notable postpolicy highlights include (1) an increase in the proportion of initial and extension requests that were automatically approved instead of manually reviewed; (2) a decrease in the overall approval rates of initial exception requests (87.8% for adult HCC, 64.3% for adult other diagnoses, and 71.5% for pediatric); and (3) reduction in the time from exception request submission to adjudication to a median of 3.73 days. The proportions of waitlist registration and deceased donor liver transplants for patients with exception scores decreased, and waitlist outcomes between patients with and without exception scores are now comparable. Implementation of the NLRB improved efficiency, reduced case workloads, and standardized criteria for exception cases, with similar waitlist outcomes between patients with and without exception scores and improved equity in terms of access to liver transplants.

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.

Current status and future directions of liver transplantation for metabolic liver disease in children

Orthotopic liver transplantation (OLT) in the care of children with inborn errors of metabolism (IEM) is well established and represent the second most common indication for pediatric liver transplantation in most centers worldwide, behind biliary atresia. OLT offers cure of disease when a metabolic defect is confined to the liver, but may still be transformative on a patient's quality of life reducing the chance of metabolic crises causing neurological damage in children be with extrahepatic involvement and no "functional cure." Outcomes post-OLT for inborn errors of metabolism are generally excellent. However, this benefit must be balanced with consideration of a composite risk of morbidity, and commitment to a lifetime of post-transplant chronic disease management. An increasing number of transplant referrals for children with IEM has contributed to strain on graft access in many parts of the world. Pragmatic evaluation of IEM referrals is essential, particularly pertinent in cases where progression of extra-hepatic disease is anticipated, with long-term outcome expected to be poor. Decision to proceed with liver transplantation is highly individualized based on the child's dynamic risk-benefit profile, their family unit, and their treating multidisciplinary team. Also to be considered is the chance of future treatments, such as gene therapies, emerging in the medium term.

Treating rare tumors with liver transplantation

PURPOSE OF REVIEW

The success of liver transplantation (LT) in treating unresectable hepatocellular carcinoma (HCC) has resulted in interest in LT for other oncologic conditions. Here, we discuss the role of LT for rare oncologic indications including metastatic gastroenteropancreatic neuroendocrine tumors (GEP-NETs), hepatic epitheliod hemangioendothelioma (HEHE), fibrolamellar hepatocellular carcinoma (FLC), and hepatic angiosarcoma (HAS).

RECENT FINDINGS

Conditions reviewed have been documented indications for LT in the available literature. We summarize the experience of LT for these indications and proposed management guidelines.

SUMMARY

GEP-NETs with isolated metastases to the liver can be treated with LT with excellent long-term outcomes (10-year survival 88%) if strict selection criteria are used (low-intermediate grade, Ki-67% < 20%, complete resection of primary tumor, stable disease for 6 months, <50% hepatic involvement). HEHE is a rare hepatic tumor for which LT can be performed with reported 10-year survival around 70%. FLC is a distinct clinical entity to HCC and is optimally treated with surgical resection though experience with LT is described in observational series (5-year survival 50%, recurrence in 10%). HAS is a rapidly progressive tumor with a dismal prognosis with or without treatment, including LT.

Transplant oncology - Current indications and strategies to advance the field

Liver transplantation (LT) was originally described by Starzl as a promising strategy to treat primary malignancies of the liver. Confronted with high recurrence rates, indications drifted towards non-oncologic liver diseases with LT finally evolving from a high-risk surgery to an almost routine surgical procedure. Continuously improving outcomes following LT and evolving oncological treatment strategies have driven renewed interest in transplant oncology. This is not only reflected by constant refinements to the criteria for LT in patients with HCC, but especially by efforts to expand indications to other primary and secondary liver malignancies. With new patient-centred oncological treatments on the rise and new technologies to expand the donor pool, the field has the chance to come full circle. In this review, we focus on the concept of transplant oncology, current indications, as well as technical and ethical aspects in the context of donor organs as precious resources.

Increasing practice and acceptable outcomes of high-MELD living donor liver transplantation in the USA

Recent deceased-donor allocation changes in the United States may have increased high-Model for End-Stage Liver Disease (MELD) living donor liver transplantation (LDLT); however, outcomes in these patients remain poorly defined. We aimed to examine the impact of the MELD score on LDLT outcomes. Using UNOS data (January 1, 2010-December 31, 2021), LDLT recipients were identified and stratified into low-MELD (<15), intermediate-MELD (15-24), and high-MELD (≥25) groups. We compared outcomes between MELD-stratified LDLT groups and between MELD-stratified LDLT and donation after brain death liver transplantation recipients. We used Kaplan-Meier analysis to compare graft survival rates and multivariable Cox proportional hazards modeling to identify factors associated with graft outcomes. Of 3558 LDLTs, 1605 (45.1%) were low-MELD, 1616 (45.4%) intermediate-MELD, and 337 (9.5%) high-MELD. Over the study period, the annual number of LDLTs increased from 282 to 569, and the proportion of high-MELD LDLTs increased from 3.9% to 7.7%. Graft survival was significantly higher in low-MELD versus high-MELD LDLT recipients (adjusted HR = 1.36, 95% CI: 1.03-1.79); however, 5-year survival exceeded 70.0% in both groups. We observed no significant difference in graft survival between high-MELD LDLT and high-MELD donation after brain death liver transplantation recipients (adjusted HR: 1.25, 95% CI:0.99-1.58), with a 5-year survival of 71.5% and 77.3%, respectively. Low LDLT center volume (<3 LDLTs/year) and recipient life support requirement were both associated with inferior graft outcomes among high-MELD LDLT recipients. While higher MELD scores confer graft failure risk in LDLT, high-MELD LDLT outcomes are acceptable with similar outcomes to MELD-stratified donation after brain death liver transplantation recipients. Future practice guidance should consider the expansion of LDLT recommendations to high-MELD recipients in centers with expertise to help reduce donor shortage.

Transplant Candidate Outcomes After Declining a DCD Liver in the United States

BACKGROUND

In the context of the organ shortage, donation after circulatory death (DCD) provides an opportunity to expand the donor pool. Although deceased-donor liver transplantation from DCD donors has expanded, DCD livers continue to be discarded at elevated rates; the use of DCD livers from older donors, or donors with comorbidities, is controversial.

METHODS

Using US registry data from 2009 to 2020, we identified 1564 candidates on whose behalf a DCD liver offer was accepted ("acceptors") and 16 981 candidates on whose behalf the same DCD offers were declined ("decliners"). We characterized outcomes of decliners using a competing risk framework and estimated the survival benefit (adjusted hazard ratio [95% confidence interval]) of accepting DCD livers using Cox regression.

RESULTS

Within 10 y of DCD offer decline, 50.9% of candidates died or were removed from the waitlist before transplantation with any type of allograft. DCD acceptors had lower mortality compared with decliners at 10 y postoffer (35.4% versus 48.9%, P < 0.001). After adjustment for candidate covariates, DCD offer acceptance was associated with a 46% reduction in mortality (0.54 [0.49-0.61]). Acceptors of older (age ≥50), obese (body mass index ≥30), hypertensive, nonlocal, diabetic, and increased risk DCD livers had 44% (0.56 [0.42-0.73]), 40% (0.60 [0.49-0.74]), 48% (0.52 [0.41-0.66]), 46% (0.54 [0.45-0.65]), 32% (0.68 [0.43-1.05]), and 45% (0.55 [0.42-0.72]) lower mortality risk compared with DCD decliners, respectively.

CONCLUSIONS

DCD offer acceptance is associated with considerable long-term survival benefits for liver transplant candidates, even with older DCD donors or donors with comorbidities. Increased recovery and utilization of DCD livers should be encouraged.

Non-invasive evaluation of hepatic macrosteatosis in deceased donors

INTRODUCTION

Liver allocation changes have led to increased travel and expenditures, highlighting the need to efficiently identify marginal livers suitable for transplant. We evaluated the validity of existing non-invasive liver quality tests and a novel machine learning-based model at predicting deceased donor macrosteatosis >30%.

METHODS

We compared previously-validated non-invasive tests and a novel machine learning-based model to biopsies in predicting macrosteatosis >30%. We also tested them in populations enriched for macrosteatosis.

RESULTS

The Hepatic Steatosis Index area-under-the-curve (AUC) was 0.56. At the threshold identified by Youden's J statistic, sensitivity, specificity, positive, and negative predictive values were 49.6%, 58.9%, 14.0%, and 89.7%. Other tests demonstrated comparable results. Machine learning produced the highest AUC (0.71). Even in populations enriched for macrosteatosis, no test was sufficiently predictive.

CONCLUSION

Commonly used clinical scoring systems and a novel machine learning-based model were not clinically useful, highlighting the importance of pre-procurement biopsies to facilitate allocation.

Palliative Care and End-of-Life Outcomes in Patients Considered for Liver Transplantation: A Single-Center Experience in the US Midwest

Introduction: Previous research has shown limited palliative care (PC) utilization among patients evaluated for liver transplantation (LT) despite the cohort's significant symptom burden, high frequency of hospitalization and risk of rapid decompensation. Our aim was to evaluate patient characteristics and end-of-life (EOL) outcomes (i.e. ICU utilization, code status, advance care planning) associated with the use of PC services in patients who were evaluated for LT. Methods: We performed a single-center cross-sectional study comprised of 223 deceased patients evaluated for LT between 1/1/2017 and 12/31/2021. We evaluated demographic characteristics and EOL outcomes for differences between patients who received PC consultation and those who did not. EOL outcomes associated with PC use were assessed using logistic and linear regression analysis adjusted for patient demographics. Results: Patients who received PC consultation were younger (mean 57 vs. 61; P = 0.048), had higher Model for end-stage Liver Disease (MELD) scores (27.5 vs. 22; P = 0.001), higher rates of hepatic encephalopathy (96% vs. 84%, P = 0.005), and were more frequently declined for LT (77% vs. 57%; P = 0.008). Patients who received PC services were less likely to die in the ICU (OR = 0.07 [0.02-0.18]) and were more likely to have documented advance care planning (OR = 3.16 [1.47-6.97]), family meetings (OR = 6.58 [2.72-17.08]), and goals-of-care discussions (OR = 14.83 [4.39-69.29]). Conclusion: For patients being evaluated for LT, PC utilization differed based on demographics, disease complications and severity, and transplant status. Those who received PC services had higher quality EOL care planning and fewer ICU admissions.

Validation of MELD 3.0 scoring system in East Asian patients with cirrhosis awaiting liver transplantation

Recently, a new predictive model that jointly considers the Model of End-stage Liver Disease (MELD) 3.0 and albumin has been proposed. This study investigated the performance of the MELD 3.0 score in predicting the 3-month survival of East Asian patients with cirrhosis compared with the other MELD-based scores. Validation was performed with the retrospective data of 2153 patients in South Korea who were listed for liver transplantation (LT). Discrimination and calibration analyses were performed using the MELD-based scores as an independent variable. On average, patients had the original MELD score of 18.70 ± 9.65. Alcohol (39.99%) and chronic HBV (38.55%) were the 2 main etiologies. The MELD 3.0 with albumin showed slightly better discrimination [c-index = 0.738, incremental AUC (iAUC) = 0.719] compared with the MELD 3.0 without albumin (c-index = 0.737, iAUC = 0.715), MELD-Na (c-index = 0.730, iAUC = 0.707), or the original MELD (c-index = 0.718, iAUC = 0.687) for predicting 3-month survival but not significantly different compared with prior models. Likewise, in the stratified analysis according to the strata of MELD, although the performance of MELD 3.0 was better throughout all the MELD strata than MELD original, there was no statistical difference in performance. The MELD 3.0 with albumin reclassified 22.61% of cases classified by the original MELD to higher MELD score categories, and there was no significant difference in the reclassification rate between males and females. The predictive power of the MELD-based system is lower in Asian populations than in western countries. Nonetheless, the MELD 3.0 score with albumin was significantly better in predicting the short-term prognosis of East Asian patients on the LT waitlist than the current allocation system, original MELD.

Characteristics of living liver donors in a national referral hospital in Indonesia: a 13-year experience with living donor liver transplantation

BACKGROUND

Hepatocellular carcinoma and biliary atresia lead to end-stage liver disease, which requires liver transplantation and is linked to increased mortality. Dr. Cipto Mangunkusumo Hospital is the national referral center in Indonesia and is the only center that routinely performs living donor liver transplantation (LDLT). This study presents the characteristics of living liver donors (LLDs) in Indonesia.

METHODS

Using the LDLT registry, we conducted a retrospective analysis of all approved donors from 2010 to 2022. The variables included clinical characteristics of the donors, graft types, and intraoperative and postoperative characteristics.

RESULTS

The LDLT rate has increased from 5.8 to 8.8 procedures/year in the last 8 years. The average age of the 76 LLDs was 31.8 years. They were predominantly female (59%) and lived within a family relationship (90%). Pediatric LDLT was more frequent than adult LDLT (88% vs. 12%, respectively). Most grafts (86%) were obtained by left lateral sectionectomy, with a median ratio of remnant liver volume to total liver volume of 79.5% (range, 47.7%-85.8%) and a mean graft-to-recipient weight ratio of 2.65%±1.21%. The median intensive care unit length of stay (LOS) was 2 days (range, 1-5 days) and the total hospital LOS was 7 days (range, 4-28 days). The complication rate was 23%. No donor mortality was reported.

CONCLUSIONS

LDLT in Indonesia has increased over the years. The shortage of donors for adult-to-adult liver transplantation is due to cultural differences and challenges in finding eligible donors. This study aims to explain the eligibility criteria of LLDs and contribute to creating a national policy.

The evolution of the liver transplant candidate

The first successful human liver transplant (LT) was done over 60 years ago; since the early pioneering days, this procedure has become a routine treatment with excellent outcomes for the great majority of recipients. Over the last six decades, indications have evolved. Use of LT for hepatic malignancy is becoming less common as factors that define a successful outcome are being increasingly defined, and alternative therapeutic options become available. Both Hepatitis B and C virus associated liver disease are becoming less common indications as medical treatments become more effective in preventing end-stage disease. Currently, the most common indications are alcohol-related liver disease and metabolic associated liver disease. The developing (and controversial) indications include acute on chronic liver failure, alcoholic hepatitis and some rarer malignancies such as non-resectable colorectal cancer liver metastases, neuroendocrine tumours and cholangiocarcinoma. Candidates are becoming older and with greater comorbidities, A relative shortage of donor organs remains the greatest cause for reducing access to LT; therefore, various countries have developed transparent approaches to allocation of this life saving and life enhancing resource. Reliance on prognostic models has gone some way to improve transparency and increase equity of access but these approaches have their limitations.

Exception points for liver transplantation: A Canadian review

Background

Exception points for liver transplant (LT) allocation are used to account for mortality risk not reflected by scoring systems such as the Model for End-Stage Liver Disease with sodium (MELD-Na). Currently, there is no formal policy regarding exception points in Canada, and differences across the country are not well understood. As such, a review of the criteria and exception points granted throughout the country for LT was conducted.

Methods

Seven LT centres in five provinces were surveyed (Vancouver, Edmonton, London, Toronto, Montréal, Halifax) regarding the indications and criteria for exception points granted, the number of points granted, how points would be accrued, and the maximum points granted.

Results

Programs in British Columbia and Nova Scotia grant variable exception points based on the median MELD-Na score with modifications; Alberta, Ontario, and Quebec grant exception points using specific values based on the indication. Overall, there was significant heterogeneity regarding exception points granted nationally with agreement only for awarding exception points for hepatopulmonary syndrome and polycystic liver disease. The second most common agreed-upon indications for exception points were portopulmonary hypertension and recurrent cholangitis offered by four provinces. Quebec had the most formal criteria for non-cirrhosis-based conditions.

Conclusions

There is substantial variance across the country regarding the indications for granting exception points as well as the number of points granted. Future work on developing a national consensus will be important for the development of equity in LT across Canada.

Abdominal Organ Transplantation: Noteworthy Literature in 2022

This review highlights noteworthy literature published in 2022 pertinent to anesthesiologists and critical care physicians caring for patients undergoing abdominal organ transplantation. We begin by exploring the impacts that the COVID-19 pandemic has had across the field of abdominal organ transplantation, including the successful use of grafts procured from COVID-19-infected donors. In pancreatic transplantation, we highlight several studies on dexmedetomidine and ischemia-reperfusion injury, equity in transplantation, and medical management, as well as studies comparing pancreatic transplantation to islet cell transplantation. In our section on intestinal transplantation, we explore donor selection. Kidney transplantation topics include cardiovascular risk management, obesity, and intraoperative management, including fluid resuscitation, dexmedetomidine, and sugammadex. The liver transplantation section focuses on clinical trials, systematic reviews, and meta-analyses published in 2022 and covers a wide range of topics, including machine perfusion, cardiovascular issues, renal issues, and coagulation/transfusion.

Addressing sex-based disparities in liver transplantation

PURPOSE OF REVIEW

Disparities in access to liver transplantation by sex have been well described, disadvantaging women. Understanding the multifactorial causes of these disparities as well as the variety of proposed solutions is critical to improving access to this life-saving intervention for women. This review aims to summarize the current body of evidence on observed sex disparities in liver transplantation and highlight actionable, evidence-based mechanisms by which these disparities can be addressed.

RECENT FINDINGS

Strategies for addressing sex disparities in liver transplantation include increasing organ utilization, changing allocation policy, and leveraging public policies to reduce the incidence of end-stage liver disease. Several other promising interventions are currently being explored.

SUMMARY

In the United States, women face additional barriers to liver transplantation on the basis of sex. Immediate action is necessary to systematically address these inequities.

The chosen and the unchosen: How eligibility for liver transplant influences the lived experiences of patients with advanced liver disease

Advanced liver disease is often uncurable and fatal. Liver transplant is the only curative option for patients with advanced, irreversible liver disease, but the need for new livers far exceeds the supply. Patients with the greatest need as well as the greatest likelihood of benefit, based on a complex array of biomedical and psychosocial considerations, are prioritized for transplant. The opportunity to receive a life-saving surgery no doubt has enormous consequences for patients and their healthcare providers, as does the absence of that opportunity. But these consequences are poorly characterized, especially for patients deemed poor candidates for liver transplant. Through in-depth interviews with patients living with advanced liver disease and the providers who care for them, we explore how eligibility status affects illness experiences, including patients' interactions with clinicians, knowledge about their disease, expectations for the future, and efforts to come to terms with a life-limiting illness. We describe how the clinical and social requirements needed to secure eligibility for liver transplant lend themselves to a clinical and cultural logic that delineates "worthy" and "unworthy" patients. We describe how providers and candidates discuss the possibility of moral redemption for such patients through transplant surgeries, a discourse notably absent among patients not eligible for transplant.

Early Impact of MMaT-3 Policy on Liver Transplant Waitlist Outcomes for Hepatocellular Carcinoma

To reduce the disparity in access to liver transplant (LT), United Network for Organ Sharing implemented an exception policy in May 2019, which capped hepatocellular carcinoma (HCC) exception score to the median Model for End-Stage Liver Disease (MELD) at transplant within the donor service area minus 3 points (MMaT-3) after the 6-mo wait period. We aimed to evaluate how this policy affected HCC waitlist outcomes.

METHODS

Using United Network for Organ Sharing data, we analyzed waitlist outcomes in HCC patients at the time they received exception points from in the pre-MMaT era (August 15, 2017, to November 15, 2018) and MMaT era (June 1, 2019, to August 30, 2020). Comparisons were made within the HCC group and HCC versus non-HCC (at time of listing) groups in the pre-MMaT and MMaT eras and regions were grouped as low, medium, and high MELD based on MMaT.

RESULTS

HCC group: LT probability within HCC patients decreased by 20% (subhazard ratio [sHR], 0.78; 95% confidence interval [CI], 0.74-0.85) between the eras and decreased by 41% in low MELD regions (sHR, 0.59; 95% CI, 0.52-0.66). Waitlist dropout was unchanged. Matched HCC versus non-HCC groups: HCC patients had 80% higher LT probability (sHR, 1.84; 95% CI, 1.71-1.99) than non-HCC patients in the pre-MMaT era; which decreased to a 14% higher LT probability in MMaT era. In low and medium regions, HCC patients had over twofold higher LT probability in the pre-MMaT era, which decreased to a ~20% higher probability (sHR, 1.14; 95% CI, 1.06-1.23) in the MMaT era. After implementation of the acuity circle policy, HCC patients had lower LT probability (sHR, 0.84; 95% CI, 0.74-0.94) than non-HCC patients.

CONCLUSIONS

The geographic disparity between HCC and non-HCC patients has improved with the MMaT-3 policy. Despite lower LT probability for HCC patients, waitlist dropout was not adversely impacted.

Consequences of Changes in the Liver Allocation System for Transplantation in the Silesian Voivodeship and in the Transplantation Center in Katowice

BACKGROUND

For a number of years, the system of procured livers for transplantation by transplant centers in a fixed order, regardless of the location of the procurement site, was in force in Poland. In mid-2018, priority was introduced in the collection of livers by a team from a given province. The aim of the study was to evaluate the impact of changing the liver transplantation allocation system at the Katowice Transplant Center (KTW) on the number of transplanted livers and on the selected parameters of donors from which the liver was procured.

METHODS

The rates and cold ischemia time (CIT) of procured livers were analyzed.

RESULTS

The rate of livers procured by the KTW transplant team increased from 36.6% to 53.3%, and at the same time the rate of livers procured by this team and sent for transplantation in other transplant centers increased. The rate of livers transplanted in the KTW, which were procured in the Silesian Voivodeship, increased from 37.4% to 61.0%, and the rate of livers procured outside the Silesian Voivodeship decreased from 54.8% to 36.4%. The CIT of livers transplanted in the KTW was reduced from 407.5 to 360.0 minutes. The comparative analysis of donor parameters of livers procured by the KTW transplant team and transplanted in Katowice revealed no differences regarding analyzed clinical and biochemical parameters.

CONCLUSION

The change in the allocation system increased the number of livers procured by the local team and shortened CIT of livers transplanted at the KTW.