Impact of Model for End-stage Liver Disease Score-based Allocation System in Korea: A Nationwide Study. Transplantation. 2019;103:2515-2522. [PMID: 30985735 DOI: 10.1097/tp.0000000000002755]

Mitigating Health Disparities in Transplantation Requires Equity, Not Equality

Despite decades of research and evidence-based mitigation strategies, disparities in access to transplantation persist for all organ types and in all stages of the transplant process. Although some strategies have shown promise for alleviating disparities, others have fallen short of the equity goal by providing the same tools and resources to all rather than tailoring the tools and resources to one's circumstances. Innovative solutions that engage all stakeholders are needed to achieve equity regardless of race, sex, age, socioeconomic status, or geography. Mitigation of disparities is paramount to ensure fair and equitable access for those with end-stage disease and to preserve the trust of the public, upon whom we rely for their willingness to donate organs. In this overview, we present a summary of recent literature demonstrating persistent disparities by stage in the transplant process, along with policies and interventions that have been implemented to combat these disparities and hypotheses for why some strategies have been more effective than others. We conclude with future directions that have been proposed by experts in the field and how these suggested strategies may help us finally arrive at equity in transplantation.

Benefit of living donor liver transplantation in graft survival for extremely high model for end-stage liver disease score ≥35

BACKGROUND AND AIMS

Living liver donation with high model for end-stage liver disease (MELD) score was discouraged despite organ shortage. This study aimed to compare graft survival between living donor liver transplantation (LDLT) and deceased donor liver transplantation (DDLT) recipients with extremely high-MELD (score of ≥35).

METHODS

Between 2008 and 2018, 359 patients who underwent liver transplantation with a MELD score ≥35 were enrolled. We compared graft survival between LDLT and DDLT after propensity score matching (PSM) and performed subgroup analysis according to donor type.

RESULTS

After PSM, there was no statistical difference in graft survival between the LDLT and DDLT groups (p = .466). Old age, acute on chronic liver failure, re-transplantation, preoperative intensive care unit stay and red blood cell (RBC) transfusion during the operation were risk factors for graft failure (p = .046, .005, .032, .015 and .001, respectively). Biliary complications were more common in the LDLT group (p = .021), while viral infection, postoperative uncontrolled ascites, and postoperative hemodialysis were more common in the DDLT group (p = .002, .018, and .027, respectively). In the LDLT group, acute chronic liver failure, intraoperative RBC transfusion, and early postoperative complications were risk factors for graft failure (p = .007, <.001, and .001, respectively).

CONCLUSION

Our study showed that LDLT is not inferior to DDLT in graft survival if appropriate risk evaluation is performed in cases of extremely high-MELD scores. This result will help overcome organ shortages in high-MELD liver transplantation.

Predicted Impact of the Model for End-Stage Liver Disease 3.0 in a Region Suffering Severe Organ Shortage

BACKGROUND

The model for end-stage liver disease 3.0 (MELD3.0) is expected to address the flaws of the current allocation system for deceased donor liver transplantation (DDLT). We aimed to validate MELD3.0 in the Korean population where living donor liver transplantation is predominant due to organ shortages.

METHODS

Korean large-volume single-centric waitlist data were merged with the Korean Network for Organ Sharing (KONOS) data. The 90-day mortality was compared between MELD and MELD3.0 using the C-index in 2,353 eligible patients registered for liver transplantation. Patient numbers and outcomes were compared based on changes in KONOS-MELD categorization using MELD3.0. Possible gains in MELD points and reduced waitlist mortality were analyzed.

RESULTS

MELD3.0 performed better than MELD (C-index 0.893 for MELD3.0 vs. 0.889 for MELD). When stratified according to the KONOS-MELD categories, 15.9% of the total patients and 35.2% of the deceased patients were up-categorized using MELD3.0 versus MELD categories. The mean gain of MELD points was higher in women (2.6 ± 2.1) than men (2.1 ± 1.9, P < 0.001), and higher in patients with severe ascites (3.3 ± 1.8) than in controls (1.9 ± 1.8, P < 0.001); however, this trend was not significant when the MELD score was higher than 30. When the possible increase in DDLT chance was calculated via up-categorizing using MELD3.0, reducible waitlist mortality was 2.7%.

CONCLUSION

MELD3.0 could predict better waitlist mortality than MELD; however, the merit for women and patients with severe ascites is uncertain, and reduced waitlist mortality from implementing MELD3.0 is limited in regions suffering from organ shortage, as in Korea.

Physical Performance Decline During the Early Posttransplantation Period Affects Survival After Living Donor Liver Transplantation

BACKGROUND

Patient physical performance has been emphasized in liver transplant recipients; however, evidence for living donor liver transplantation (LDLT) patients is lacking. This study investigated the impact of physical performance decline during the early posttransplantation period on survival and risk factors for this decline in LDLT recipients.

METHODS

From national registry data, 2703 LDLT patients were divided into 2 groups based on the change in their Karnofsky performance status (KPS) between 1 and 6 mo posttransplantation: declined KPS (n = 188) and control (n = 2515). Multivariable analyses were conducted to control for confounders, including posttransplantation complications.

RESULTS

Estimated 5-y patient survival rates were 91.6% in the declined KPS group and 96.3% in the control group, favoring the latter ( P = 0.003). The survival hazard of KPS decline was significant in a baseline covariates-adjusted Cox model (hazard ratio [HR], 2.60; 95% confidence interval [CI], 1.37-4.95) and an adjusted model accounting for posttransplantation complications (HR, 3.38; 95% CI, 1.70-6.72). In subgroup analyses, KPS decline independently reduced survival in patients without complications (HR, 3.95; 95% CI, 1.67-9.34), and the trend was similar in patients with complications, although significance was marginal (HR, 3.02; 95% CI, 0.98-9.27). We found that only posttransplantation complications, such as rejection, infection, bile duct complication, and vascular complication, were significant risk factors for KPS decline after LDLT.

CONCLUSIONS

Physical performance decline during the early posttransplantation period independently reduced survival rates, and posttransplantation complications were the only significant risk factors for physical performance decline in LDLT recipients.

The impact of Model for End-Stage Liver Disease score on deceased donor liver transplant outcomes in low volume liver transplantation center: a retrospective and single-center study

PURPOSE

In June 2016, the Model for End-Stage Liver Disease (MELD) score was employed in South Korea instead of the Child-Turcotte-Pugh (CTP) score. This study compared the outcomes of deceased donor liver transplantation (DDLT) before and after the MELD system application.

METHODS

This retrospective study reviewed 48 patients who underwent DDLT for end-stage liver disease at a single tertiary referral center between January 2014 and December 2018. The patients were categorized into the pre-MELD (22 patients) and post-MELD (26 patients) groups. The demographics, postoperative outcomes, and overall survival time were evaluated between the 2 groups.

RESULTS

The 2 groups had no differences in age, sex, ABO type, etiology for liver transplantation, CTP-score, operation time, cold ischemic time, and amount of red blood cell transfusion, although their MELD score differed significantly (post-MELD group, 36.2 ± 4.9; pre-MELD group, 27.7 ± 11.8; P < 0.001). The post-MELD group has longer intensive care unit stay (11.2 ± 9.5 days vs. 5.7 ± 4.5 days, P = 0.018) and hospital stay than the pre-MELD group (36.8 ± 26 days vs. 22.8 ± 9.3 days, P = 0.016). The 1-year survival rate was lower in the post-MELD group (61.5% vs. 86.4%, P = 0.029).

CONCLUSION

After MELD allocation, patients with high MELD scores had increased DDLT and consequently required a longer recovery time, which could negatively affect survival. According to the experience of a small-volume center, these problems were related to both severe organ shortages in South Korea and MELD allocation.

Systemic Immune-Inflammatory Marker of High Meld Patients Is Associated With Early Mortality After Liver Transplantation

The scarcity of deceased donor livers has led to allocation of grafts to only the most seriously ill patients with a high Model for End-Stage Liver Disease (MELD) score, which has resulted in a high mortality rate after deceased donor liver transplantation (DDLT). The aim of this study is to identify risk factors for posttransplant mortality and thereby reduce futile outcomes in DDLT. Between 2013 and 2019, 57 recipients with MELD scores ≥30 underwent DDLT in our center. We retrieved data and identified the risk factors for 90-day posttransplant mortality. The perioperative clinical and laboratory parameters of patients who did or did not survive for 90 days were subjected to logistic regression analysis. Twelve patients died within 90 days. Results of univariate analysis indicated that the differences in patient survival were determined by the amount of intraoperative platelets transfused, the presence of posttransplant septicemia, and systemic immune-inflammation index (SII) at the time of listing with MELD scores ≥30. Multivariate analysis revealed that an SII ≥870 (× 10⁹/L) and posttransplant septicemia were independent risk factors for 90-day mortality. Twenty-two patients had SIIs ≥870, and 13 of these patients had posttransplant septicemia. Of the 13 patients, 90-day mortality occurred in 10 cases. However, in 35 patients with SIIs <870, 90-day mortality due to posttransplant septicemia was recorded only in 1 patient. In conclusion, a preoperative SII ≥870 in a patient with a high MELD score may be a significant risk factor for early posttransplant mortality. Because posttransplant septicemia in patients with high SIIs can lead to fatality, a more intensive effort to prevent infection is needed for patients undergoing DDLT carrying such risk factors to avoid futile liver transplantation.

Evolution of liver transplant organ allocation policy: Current limitations and future directions

Since the adoption of the model for end-stage liver disease (MELD) score for organ allocation in 2002, numerous changes to the system of liver allocation and distribution have been made with the goal of decreasing waitlist mortality and minimizing geographic variability in median MELD score at time of transplant without worsening post-transplant outcomes. These changes include the creation and adoption of the MELD-Na score for allocation, Regional Share 15, Regional Share for Status 1, Regional Share 35/National Share 15, and, most recently, the Acuity Circles Distribution Model. However, geographic differences in median MELD at time of transplant remain as well as limits to the MELD score for allocation, as etiology of liver disease and need for transplant changes. Acute-on-chronic liver failure (ACLF) is a subset of liver failure where prevalence is rising and has been shown to have an increased mortality rate and need for transplantation that is under-demonstrated by the MELD score. This underscores the limitations of the MELD score and raises the question of whether MELD is the most accurate, objective allocation system. Alternatives to the MELD score have been proposed and studied, however MELD score remains as the current system used for allocation. This review highlights policy changes since the adoption of the MELD score, addresses limitations of the MELD score, reviews proposed alternatives to MELD, and examines the specific implications of these changes and alternatives for ACLF.

Statistical methods versus machine learning techniques for donor-recipient matching in liver transplantation

Donor-Recipient (D-R) matching is one of the main challenges to be fulfilled nowadays. Due to the increasing number of recipients and the small amount of donors in liver transplantation, the allocation method is crucial. In this paper, to establish a fair comparison, the United Network for Organ Sharing database was used with 4 different end-points (3 months, and 1, 2 and 5 years), with a total of 39, 189 D-R pairs and 28 donor and recipient variables. Modelling techniques were divided into two groups: 1) classical statistical methods, including Logistic Regression (LR) and Naïve Bayes (NB), and 2) standard machine learning techniques, including Multilayer Perceptron (MLP), Random Forest (RF), Gradient Boosting (GB) or Support Vector Machines (SVM), among others. The methods were compared with standard scores, MELD, SOFT and BAR. For the 5-years end-point, LR (AUC = 0.654) outperformed several machine learning techniques, such as MLP (AUC = 0.599), GB (AUC = 0.600), SVM (AUC = 0.624) or RF (AUC = 0.644), among others. Moreover, LR also outperformed standard scores. The same pattern was reproduced for the others 3 end-points. Complex machine learning methods were not able to improve the performance of liver allocation, probably due to the implicit limitations associated to the collection process of the database.

Liver Transplantation Selection and Allocation Criteria for Hepatocellular Carcinoma: A European Perspective

For patients with early-stage hepatocellular carcinoma (HCC), liver transplantation offers the best chance of cure. Over the past two decades, selection criteria to determine eligibility for liver transplantation have been constantly refined but a fair allocation strategy of liver grafts to HCC patients remains challenging. In Europe, over a dozen transplantation networks apply different liver transplantation criteria for HCC patients. In this review, we explore and compare candidate selection and liver graft allocation strategies for patients with HCC with a European perspective and discuss the ethical and technical challenges involved. In addition, we suggest possible paths for future improvement such as transitioning from fixed selection and allocation criteria to a more flexible model of benefit, which includes criteria concerning the graft, response to treatment, the biology of the tumor, and other relevant recipient factors.

Outcome of patients with severe alcoholic hepatitis after Model for End-Stage Liver Disease-based allocation system implementation in Korea

Background

The Model for End-Stage Liver Disease (MELD)-based allocation system was implemented in Korea in July 2016 without a mandatory abstinence period for liver transplantation (LT) listing. However, the impact of the allocation policy has not been evaluated in patients with severe alcoholic hepatitis (AH).

Methods

A total of 81 consecutive patients with severe AH between January 2014 and December 2018 were analyzed. The clinical course of patients before and after the implementation of the MELD-based allocation system was assessed.

Results

More patients received LT (25%–65%) after the MELD allocation system was implemented. The increase in patients receiving deceased donor LT was dramatic (17%–51%, P=0.001) compared to patients receiving living donor LT (7%–14%, P=0.30). The overall survival was better for those who received LT (88% vs. 44% at 1 year, P<0.001), and after the MELD era (1-year survival rate 80% vs. 50%, P=0.005). Post-LT mortality was observed in six patients, with one case of mortality related to recidivism. Baseline MELD and steroid response were factors associated with transplant-free survival.

Conclusions

After implementation of the MELD-based allocation system, deceased donor LT dramatically increased in patients with severe AH. This translated into increased overall survival, but at a cost of mortality due to recidivism. Urgent evaluation is warranted to identify criteria to justify the use of precious liver grafts from deceased donors for severe AH patients in Korea.