Excellent Liver Transplant Survival Rates Under the MELD/PELD System

Artificial intelligence and human liver allocation: Potential benefits and ethical implications

Since its implementation almost two decades ago, the urgency allocation policy has improved the survival of patients on the waiting list for liver transplantation worldwide. The Model for End-Stage Liver Disease score is widely used to predict waiting list mortality. Due to some limitations related to its use, there is an active investigation to develop other prognostic scores. Liver allocation (LA) entails complex decision-making, and grafts are occasionally not directed to the recipients who are more likely to survive. Prognostic scores have, thus far, failed to predict post-operatory survival. Furthermore, the increasing use of marginal donors is associated with worse outcomes. Adequate donor-recipient pairing could help avoid retransplantation or futile procedures and reduce postoperative complications, mortality, hospitalization time, and costs. Artificial intelligence has applications in several medical fields. Machine learning algorithms (MLAs) use large amounts of data to detect unforeseen patterns and complex interactions between variables. Artificial neural networks and decision trees were the most common forms of MLA tested on LA. Some researchers have shown them to be superior for predicting waiting list mortality and graft failure than conventional statistical methods. These promising techniques are increasingly being considered for implementation.

Clinical outcome of 1,000 consecutive cases of liver transplantation: a single center experience

Purpose

The aim of this study was to analyze survival outcomes in 1,000 consecutive liver transplantations (LTs) performed at a single institution from 1993 to April 2017.

Methods

The study population was divided into 2 groups based on donor type: deceased donor LT (DDLT; n = 181, 18.1%) and living donor LT (LDLT; n = 819; 81.9%), and into 3 periods based on the number of cases (first 300 cases, middle 300 cases, last 400 cases).

Results

Infection was the most common cause of death, accounting for 34.8% (95 of 273). Mortality due to hepatocellular carcinoma recurrence occurred most frequently between 1 and 5 years after transplantation. Mortality rate by graft rejection was highest between 5 and 10 years after transplantation. And mortality by de novo malignancy occurred most frequently after 10 years after transplantation. The patient survival rates for the entire population at 5 and 10 years were 74.7%, and 68.6%, respectively. There was no difference in survival rate between the LDLT and DDLT groups (P = 0.188). Cause of disease, disease severity, case period, and retransplantation had a significant association with patient survival (P = 0.002, P = 0.031, P = 0.003, and P = 0.024, respectively).

Conclusion

Surgical techniques and perioperative management for transplant patients have improved and undergone standardization. Controlling perioperative infection and managing patients with HCC as LT candidates will result in better outcomes.

Transplant-related survival benefit should influence prioritization for liver transplantation especially in patients with hepatocellular carcinoma

Transplant-related survival benefit is calculated as the difference between life expectancy with transplantation and life expectancy without transplantation. Determining eligibility and prioritization for liver transplantation based on the highest survival benefit is a superior strategy to prioritization based on the highest urgency (ie, the highest wait-list mortality) or the highest utility (ie, the highest posttransplant survival) because prioritization based on the highest survival benefit maximizes the overall life expectancy of all patients in need of liver transplantation. Although the Model for End-Stage Liver Disease (MELD)-based prioritization system was designed as an urgency-based system, in practice it functions to a large extent as a survival benefit-based system, when the natural MELD score is used without exceptions. Survival benefit considerations should be used to determine the consequences of deviating from prioritization based on the natural MELD score, such as when exception points are awarded to patients with hepatocellular carcinoma (HCC) that are independent of MELD score or tumor burden, or the appropriateness of expanding eligibility for transplantation. The most promising application of survival benefit-based prioritization would be to replace the current system of prioritization of patients with HCC by one that uses their natural MELD score and tumor characteristics such as HCC tumor burden, serum alpha fetoprotein level, and response to locoregional therapies to predict the impact on survival benefit caused by the presence of HCC and adjust the natural MELD score for prioritization accordingly. Liver Transplantation 23 652-662, 2017 AASLD.

Model for End-Stage Liver Disease-Sodium Score: The Evolution in the Prioritization of Liver Transplantation

The adoption of the model of end-stage liver disease (MELD) score as surrogate marker of liver disease severity has been the greatest change in liver allocation. Since its implementation, waiting time has lost significance. The MELD score calculation was later modified to reflect the contribution of hyponatremia in the estimation of mortality risk. However, the MELD score does not capture accurately the risk of mortality of patients with hepatocellular carcinoma (HCC). Therefore the arbitrary assignment of MELD points has been used for HCC patients. The current allocation system still prioritizes transplantation in HCC patients.

Improving the Diagnostic Criteria for Primary Liver Graft Nonfunction in Adults Utilizing Standard and Transportable Laboratory Parameters: An Outcome-Based Analysis

Current diagnostic criteria for primary nonfunction (PNF) of liver grafts are based on clinical experience rather than statistical methods. A retrospective, single-center study was conducted of all adults (n = 1286) who underwent primary liver transplant (LT) 2000-2008 in our center. Laboratory variables during the first post LT week were analyzed. Forty-two patients (3.7%) had 2-week graft failure. Transplant albumin, day-1 aspartate aminotransferase (AST), day-1 lactate, day-3 bilirubin, day-3 international normalized ratio (INR), and day-7 AST were independently associated with PNF on multivariate logistic regression. PNF score =(0.000280*D1AST)+ (0.361*D1 Lactate)+(0.00884*D3 Bilirubin)+(0.940*D3 INR)+(0.00153*D7 AST)-(0.0972*TxAlbumin)-4.5503. Receiver operating curve analysis showed the model area under receiver operating curve (AUROC) of 0.912 (0.889-0.932) was superior to the current United Kingdom (UK) PNF criteria of 0.669 (0.634-0.704, p < 0.0001). When applied to a validation cohort (n = 386, 34.4% patients), the model had AUROC of 0.831 (0.789-0.867) compared to the UK early graft dysfunction criteria of 0.674 (0.624-0.721). The new model performed well after exclusion of patients with marginal grafts and when modified to include variables from the first three post-LT days only (AUROC of 0.818, 0.776-0.856, p = 0.001). This model is superior to the current UK PNF criteria and is based on statistical methods. The model is also applicable to recipients of all types of grafts (marginal and nonmarginal).

Preoperative risk factors for intra-operative bleeding in pediatric liver transplantation

This study analyzes the preoperative risk factors for intra-operative bleeding in our recent series of pediatric LTs. Between November 2009 and November 2014, 84 consecutive isolated pediatric LTs were performed in 81 children. Potential preoperative predictive factors for bleeding, amount of intra-operative transfusions, postoperative course, and outcome were recorded. Cutoff point for intra-operative HBL was defined as intra-operative RBC transfusions ≥1 TBV. Twenty-six patients (31%) had intra-operative HBL. One-year patient survival after LT was 66.7% (CI 95%=[50.2-88.5]) in HBL patients and 83.8% (CI 95%=[74.6-94.1]) in the others (P=.054). Among 13 potential preoperative risk factors, three of them were identified as independent predictors of high intra-operative bleeding: abdominal surgical procedure(s) prior to LT, factor V level ≤30% before transplantation, and ex situ parenchymal transsection of the liver graft. Based on these findings, we propose a simple score to predict the individual hemorrhagic risk related to each patient and graft association. This score may help to better anticipate intra-operative bleeding and improve patient's management.

One Size Does Not Fit All--Regional Variation in the Impact of the Share 35 Liver Allocation Policy

Allocation policies for liver transplantation underwent significant changes in June 2013 with the introduction of Share 35. We aimed to examine the effect of Share 35 on regional variation in posttransplant outcomes. We examined two patient groups from the United Network for Organ Sharing dataset; a pre-Share 35 group composed of patients transplanted between June 17, 2012, and June 17, 2013 (n = 5523), and a post-Share group composed of patients transplanted between June 18, 2013, and June 18, 2014 (n = 5815). We used Kaplan-Meier and Cox multivariable analyses to compare survival. There were significant increases in allocation Model for End-stage Liver Disease (MELD) scores, laboratory MELD scores, and proportions of patients in the intensive care unit and on mechanical, ventilated, or organ-perfusion support at transplant post-Share 35. We also observed a significant increase in donor risk index in this group. We found no difference on a national level in survival between patients transplanted pre-Share 35 and post-Share 35 (p = 0.987). Regionally, however, posttransplantation survival was significantly worse in the post-Share 35 patients in regions 4 and 10 (p = 0.008 and p = 0.04), with no significant differences in the remaining regions. These results suggest that Share 35 has been associated with transplanting "sicker patients" with higher MELD scores, and although no difference in survival is observed on a national level, outcomes appear to be concerning in some regions.

Model for end-stage liver disease score and MELD exceptions: 15 years later

The model for end-stage liver disease (MELD) score has been used as an objective scale of disease severity for management of patients with end-stage liver disease; it currently serves as the basis of an urgency-based organ-allocation policy in several countries. Implementation of the MELD score led to a reduction in waiting-list registration and waiting-list mortality and an increase in the number of deceased-donor transplants without adversely affecting long-term outcomes after liver transplantation (LT). The MELD score has been used for management of non-transplant patients with chronic liver disease. MELD exceptions serve as a mechanism to advance the needs of subsets of patients with liver disease not adequately addressed by MELD-based organ allocation. Several models have been proposed to refine and improve the MELD score as the environment within which it operates continues to evolve toward transplantation for sicker patients. The MELD score continues to serve and be used as a template to improve upon as an objective gauge of disease severity and as a metric enabling optimization of allocation of scarce donor organs for LT.

Predicting survival after liver transplantation based on pre-transplant MELD score: a systematic review of the literature

The model for end-stage liver disease (MELD) score is used to stratify candidates for liver transplantation based on objective measures of disease severity. MELD has been validated as a predictor of wait-list mortality in transplantation candidates and has been postulated as a predictor of post-transplant survival. The purpose of this study was to examine the predictive value of the pre-transplantation MELD score on post-transplant survival from relevant existing studies. A systematic review and critical appraisal was performed using Cochrane guidelines. PubMed, the Cochrane Library, Embase, and Web of Science were searched for articles published in the English language since 2005 using a structured search strategy. There were 3058 discrete citations identified and screened for possible inclusion. Any study examining the relationship between pre-transplant MELD and post-transplant survival in the general transplant population was included. Thirty-seven studies met these criteria and were included in the review. Studies were all case series that typically involved stratified analyses of survival by MELD. They represented 15 countries and a total of 53,691 patients. There was significant clinical heterogeneity in patient populations across studies, which precluded performance of a meta-analysis. In 15 studies, no statistically significant association between MELD and post-transplant survival was found. In the remaining 22, some association was found. Eleven studies also measured predictive ability with c-statistics. Values were below 0.7 in all but two studies, suggesting poor predictive value. In summary, while the majority of studies reported an association between pre-transplantation MELD score and post-transplant survival, they represented a low level of evidence. Therefore, their findings should be interpreted conservatively.

Improved waiting-list outcomes in Argentina after the adoption of a model for end-stage liver disease-based liver allocation policy

In July 2005, Argentina became the first country after the United States to introduce the Model for End-Stage Liver Disease (MELD) for organ allocation. In this study, we investigated waiting-list (WL) outcomes (n = 3272) and post-liver transplantation (LT) survival in 2 consecutive periods of 5 years before and after the implementation of a MELD-based allocation policy. Data were obtained from the database of the national institute for organ allocation in Argentina. After the adoption of the MELD system, there were significant reductions in WL mortality [28.5% versus 21.9%, P < 0.001, hazard ratio (HR) = 1.57, 95% confidence interval (CI) = 1.37-1.81] and total dropout rates (38.6% versus 29.1%, P < 0.001, HR = 1.31, 95% CI = 1.16-1.48) despite significantly less LT accessibility (57.4% versus 50.7%, P < 0.001, HR = 1.53, 95% CI = 1.39-1.68). The annual number of deaths per 1000 patient-years at risk decreased from 273 in 2005 to 173 in 2010, and the number of LT procedures per 1000 patient-years at risk decreased from 564 to 422. MELD and Model for End-Stage Liver Disease-Sodium scores were excellent predictors of 3-month WL mortality with c statistics of 0.828 and 0.857, respectively (P < 0.001). No difference was observed in 1-year posttransplant survival between the 2 periods (81.1% versus 81.3%). Although patients with a MELD score > 30 had lower posttransplant survival, the global accuracy of the score for predicting outcomes was poor, as indicated by a c statistic of only 0.523. Patients with granted MELD exceptions (158 for hepatocellular carcinoma and 52 for other reasons) had significantly higher access to LT (80.4%) in comparison with nonexception patients with equivalent listing priority (MELD score = 18-25; 54.6%, P < 0.001, HR = 0.49, 95% CI = 0.40-0.61). In conclusion, the adoption of the MELD model in Argentina has resulted in improved liver organ allocation without compromising posttransplant survival.

Model for end-stage liver disease: end of the first decade

The Model for End-stage Liver Disease (MELD) score is the basis for allocation of liver allografts for transplantation in the United States. The MELD score, as an objective scale of disease severity, is also used in the management of patients with chronic liver disease in the nontransplant setting. Several models have been proposed to improve the MELD score. The authors believe that the MELD score is, by design, continually evolving and lends itself to continued refinement and improvement to serve as a metric to optimize organ allocation in the future.

Regional variability in symptom-based MELD exceptions: a response to organ shortage?

MELD (model for end-stage liver disease) exception awards affect the liver allocation process. Award rates of specific nonhepatocellular carcinoma exceptions, termed symptom-based exceptions (SBE), differ across UNOS regions. We aimed to characterize the regional variability in SBE awards and examine predictive factors for receiving a SBE in the MELD era. The OPTN liver transplant and waiting list dataset was analyzed for waiting list registrants during the MELD allocation on February 27, 2002, until November 22, 2006. Competing risks proportional hazards regression analysis was used to examine predictors for receiving a SBE in 39 169 registrants. The hazard ratios for receiving a SBE differed significantly across regions when adjusted for multiple variables including age, gender, ethnicity, physiologic MELD score, blood group, functional status, etiology of liver disease, insurer and education level. Utilization of SBE is highly significantly variable across UNOS regions, and does not correlate with organ availability as estimated by the regional mean physiologic MELD score at transplantation. Patients with Medicaid as their primary payer have a lower likelihood of receiving a SBE award, while patients with cryptogenic/NASH cirrhosis or cholestatic liver disease have a higher likelihood of receiving a SBE. Reasons for these regional and demographic disparities deserve further investigation.

The model for end-stage liver disease allocation system for liver transplantation saves lives, but increases morbidity and cost: a prospective outcome analysis

We analyzed the first 100 patients who underwent liver transplantation by Model for End-Stage Liver Disease (MELD) allocation, and compared the outcome of patients on the waiting list and after orthotopic liver transplantation with the last 100 patients who underwent transplantation prior to the introduction of the MELD system in July 2007. MELD allocation resulted in decreased waiting list mortality (386 versus 242 deaths per 1000 patient-years, P < 0.0001) and the transplantation of sicker recipients (uncorrected median MELD score 13.5 versus 20, P = 0.003). Recipient posttransplant morbidity was significantly higher, mainly caused by increased percentage of renal failure requiring renal replacement therapy (13 versus 46%, P < 0.0001). However, kidney function recovered in most cases within 6 months after OLT. Hospital mortality remained similar in both groups (6% versus 9%). Patient 1-year survival was 91% versus 83% (pre-MELD versus MELD era, P = 0.2154), graft 1-year survival was 88% versus 78% (P = 0.1013), respectively. Costs accumulated were significantly higher after introduction of the MELD policy (US $81,967 versus US $127,453, a 55% increase, P = 0.02) with a strong correlation with the individual MELD score (P < 0.0001). The MELD system addresses the goal of fairness well. However, the postoperative course appears more difficult in the MELD era with increased financial burden, but reasonable patient and graft survival. This is the inevitable price to balance justice and utility in liver graft allocation.

[The application of MELD score in patients submitted to liver transplantation: a retrospective analysis of survival and the predictive factors in the short and long term]

BACKGROUND

The model for end-stage liver disease (MELD) was developed to predict short-term mortality in patients with cirrhosis. There are few reports studying the correlation between MELD and long-term posttransplantation survival.

AIM

To assess the value of pretransplant MELD in the prediction of posttransplant survival.

METHODS

The adult patients (age >18 years) who underwent liver transplantation were examined in a retrospective longitudinal cohort of patients, through the prospective data base. We excluded acute liver failure, retransplantation and reduced or split-livers. The liver donors were evaluated according to: age, sex, weight, creatinine, bilirubin, sodium, aspartate aminotransferase, personal antecedents, brain death cause, steatosis, expanded criteria donor number and index donor risk. The recipients' data were: sex, age, weight, chronic hepatic disease, Child-Turcotte-Pugh points, pretransplant and initial MELD score, pretransplant creatinine clearance, sodium, cold and warm ischemia times, hospital length of stay, blood requirements, and alanine aminotransferase (ALT >1,000 UI/L = liver dysfunction). The Kaplan-Meier method with the log-rank test was used for the univariable analyses of posttransplant patient survival. For the multivariable analyses the Cox proportional hazard regression method with the stepwise procedure was used with stratifying sodium and MELD as variables. ROC curve was used to define area under the curve for MELD and Child-Turcotte-Pugh.

RESULTS

A total of 232 patients with 10 years follow up were available. The MELD cutoff was 20 and Child-Turcotte-Pugh cutoff was 11.5. For MELD score > or =20, the risk factors for death were: red cell requirements, liver dysfunction and donor's sodium. For the patients with hyponatremia the risk factors were: negative delta-MELD score, red cell requirements, liver dysfunction and donor's sodium. The regression univariated analyses came up with the following risk factors for death: score MELD > or = 25, blood requirements, recipient creatinine clearance pretransplant and age donor > or =50. After stepwise analyses, only red cell requirement was predictive. Patients with MELD score < 25 had a 68.86%, 50,44% and 41,50% chance for 1, 5 and 10-year survival and > or =25 were 39.13%, 29.81% and 22.36% respectively. Patients without hyponatremia were 65.16%, 50.28% and 41,98% and with hyponatremia 44.44%, 34.28% and 28.57% respectively. Patients with IDR > or =1.7 showed 53.7%, 27.71% and 13.85% and index donor risk <1.7 was 63.62%, 51.4% and 44.08%, respectively. Age donor > 50 years showed 38.4%, 26.21% and 13.1% and age donor < or =50 years showed 65.58%, 26.21% and 13.1%. Association with delta-MELD score did not show any significant difference. Expanded criteria donors were associated with primary non-function and severe liver dysfunction. Predictive factors for death were blood requirements, hyponatremia, liver dysfunction and donor's sodium.

CONCLUSION

In conclusion MELD over 25, recipient's hyponatremia, blood requirements, donor's sodium were associated with poor survival.

Allocation priority in non-urgent liver transplantation: An overview of proposed scoring systems

Given the lack of donors, a correct organ allocation system for candidates to liver transplantation is essential to increase graft and patient survival. The most used organ allocation tools are Child-Turcotte-Pugh and model for end-stage liver disease. It is generally accepted that model for end-stage liver disease score is superior to the Child-Turcotte-Pugh classification in predicting the short-term survival of cirrhotic patients awaiting liver transplantation. Since 2002, model for end-stage liver disease is widely used for liver allocation. In recent years, to overcome limitations of the consolidated scores, some adjustments to the original model for end-stage liver disease formula and new scoring systems have been proposed. Published data suggest that integrating serum sodium and model for end-stage liver disease may improve the score prognostic accuracy but further studies are necessary to confirm this issue. The updated model for end-stage liver disease, obtained through a revision of traditional model for end-stage liver disease parameters and tested in a large cohort of patients, is of great interest at the moment. In conclusion, several scoring systems have been described for organ allocation, but today, none is definitely able to overcome the limitations of the Child-Turcotte-Pugh and model for end-stage liver disease systems.

Should liver transplantation in patients with model for end-stage liver disease scores <or= 14 be avoided? A decision analysis approach

Studies have shown that liver transplantation offers no survival benefits to patients with Model for End-Stage Liver Disease (MELD) scores <or= 14 in comparison with remaining on the waitlist. The consensus of a 2003 transplant community national conference was that a minimum MELD score should be required for placement on the liver waitlist, but no minimum listing national policy was enacted at that time. We developed a Markov microsimulation model to compare results under the present US liver allocation policy with outcomes under a "Rule 14" policy of barring patients with a MELD score of <or=14 from the waitlist or transplantation. For probabilities in the microsimulation model, we used data on all adult patients (>or=18 years) listed for or undergoing primary liver transplantation in the United States for chronic liver disease from 1/1/2003 through 12/31/2007 with follow-up until 2/1/2008. The "Rule 14" policy gave a 3% improvement in overall patient survival over the present system at 1, 2, 3, and 4 years and predicted a 13% decrease in overall waitlist time for patients with MELD scores of 15 to 40. Patients with the greatest benefit from a "Rule 14" policy were those with MELD scores of 6 to 10, for whom a 17% survival advantage was predicted from waiting on the list versus undergoing transplantation. Our analysis supports changing the national liver allocation policy to not allow liver transplantation for patients with MELD <or= 14.

Hyponatremia and mortality among patients on the liver-transplant waiting list

BACKGROUND

Under the current liver-transplantation policy, donor organs are offered to patients with the highest risk of death.

METHODS

Using data derived from all adult candidates for primary liver transplantation who were registered with the Organ Procurement and Transplantation Network in 2005 and 2006, we developed and validated a multivariable survival model to predict mortality at 90 days after registration. The predictor variable was the Model for End-Stage Liver Disease (MELD) score with and without the addition of the serum sodium concentration. The MELD score (on a scale of 6 to 40, with higher values indicating more severe disease) is calculated on the basis of the serum bilirubin and creatinine concentrations and the international normalized ratio for the prothrombin time.

RESULTS

In 2005, there were 6769 registrants, including 1781 who underwent liver transplantation and 422 who died within 90 days after registration on the waiting list. Both the MELD score and the serum sodium concentration were significantly associated with mortality (hazard ratio for death, 1.21 per MELD point and 1.05 per 1-unit decrease in the serum sodium concentration for values between 125 and 140 mmol per liter; P<0.001 for both variables). Furthermore, a significant interaction was found between the MELD score and the serum sodium concentration, indicating that the effect of the serum sodium concentration was greater in patients with a low MELD score. When applied to the data from 2006, when 477 patients died within 3 months after registration on the waiting list, the combination of the MELD score and the serum sodium concentration was considerably higher than the MELD score alone in 32 patients who died (7%). Thus, assignment of priority according to the MELD score combined with the serum sodium concentration might have resulted in transplantation and prevented death.

CONCLUSIONS

This population-wide study shows that the MELD score and the serum sodium concentration are important predictors of survival among candidates for liver transplantation.

Hyponatremia and mortality among patients on the liver-transplant waiting list

BACKGROUND

Under the current liver-transplantation policy, donor organs are offered to patients with the highest risk of death.

METHODS

Using data derived from all adult candidates for primary liver transplantation who were registered with the Organ Procurement and Transplantation Network in 2005 and 2006, we developed and validated a multivariable survival model to predict mortality at 90 days after registration. The predictor variable was the Model for End-Stage Liver Disease (MELD) score with and without the addition of the serum sodium concentration. The MELD score (on a scale of 6 to 40, with higher values indicating more severe disease) is calculated on the basis of the serum bilirubin and creatinine concentrations and the international normalized ratio for the prothrombin time.

RESULTS

In 2005, there were 6769 registrants, including 1781 who underwent liver transplantation and 422 who died within 90 days after registration on the waiting list. Both the MELD score and the serum sodium concentration were significantly associated with mortality (hazard ratio for death, 1.21 per MELD point and 1.05 per 1-unit decrease in the serum sodium concentration for values between 125 and 140 mmol per liter; P<0.001 for both variables). Furthermore, a significant interaction was found between the MELD score and the serum sodium concentration, indicating that the effect of the serum sodium concentration was greater in patients with a low MELD score. When applied to the data from 2006, when 477 patients died within 3 months after registration on the waiting list, the combination of the MELD score and the serum sodium concentration was considerably higher than the MELD score alone in 32 patients who died (7%). Thus, assignment of priority according to the MELD score combined with the serum sodium concentration might have resulted in transplantation and prevented death.

CONCLUSIONS

This population-wide study shows that the MELD score and the serum sodium concentration are important predictors of survival among candidates for liver transplantation.

Primary nonfunction (PNF) in the MELD Era: An SRTR database analysis

PNF following liver transplantation (LT) is an infrequent but life-threatening complication. Liver allocation under MELD is based upon recipient severity of illness, a known risk factor for the occurrence of PNF. The incidence of PNF since the application of MELD has not previously been reported. The SRTR database was studied since inception of MELD until September 2004 for all adult recipients of deceased donor LT. PNF was defined as graft loss or death within 14 days of LT secondary to PNF or without defined cause. A total of 10545 transplants met inclusion criteria and PNF occurred in 613 (5.81%) of recipients. Univariate analysis demonstrated donor age, serum creatinine >1.5 mg/mL, hypertension and CVA as risk factors for PNF. Recipient factors included life support, mechanical ventilation, use of inotropes, hemodialysis, initial status 1 and use of a shared transplant. In the multivariate model only donor age and recipient serum creatinine, bilirubin, on life support and status 1 at transplant were significant risk factors for PNF. In this analysis of PNF in the MELD era the incidence of PNF does not appear to have increased from prior reports. Risk factors for PNF are related to donor age and severity of recipient illness.

Liver transplantation organ allocation between Child and MELD

Liver transplantation (LT) has been established as the most effective therapy for acute and chronic liver diseases over the last few decades due to its excellent long-term results. At the beginning of the LT era, donor organs were allocated based on waiting time. However, as the number of LT candidates consistently increased, a specific allocation system became necessary to prioritize the large number of patients waiting for a limited pool of organs. The LT candidates were categorized into different urgency levels based on their hospital status, degree of liver disease as measured by the Child-Turcotte-Pugh score, and accompanying complications of liver disease, such as ascites, variceal bleeding or hepatocellular carcinoma. The majority of European countries, including Austria, still rely on this organ allocation system. In the United States, however, a new allocation system based on the risk of death without transplantation, assessed by the Model for End-stage Liver Disease (MELD), was initiated in February 2002. Recent reports have shown that the introduction of the MELD system led to a reduction in waiting list mortality, but also that the MELD score has several limitations that call for further refinements. In the transplant community there are reasonable doubts that MELD is actually superior to the Child-Turcotte Pugh score. Therefore, the optimal liver organ allocation system is yet to be defined.

Model for end-stage liver disease and organ allocation in liver transplantation: where are we and where should we go?

The Child-Turcotte-Pugh (CTP) score has been used for decades to measure the severity of chronic liver disease. Recent studies have shown that the model for end-stage liver disease (MELD) more accurately predicts the short- and mid-term survival for patients with cirrhosis compared to the CTP system. MELD, which has 3 parameters (serum bilirubin, creatinine, and prothrombin time) that need logarithmic transformation, has the advantage of a wide-range continuous scale and is more objective and less variable. The liver allocation system has changed from a status-based algorithm using the CTP score, to one using a continuous MELD severity score as a reference system to prioritize adult patients on the waiting list since 2002 in the USA. However, there are potential limitations of MELD. An intrinsic defect is that some important parameters, such as hepatic encephalopathy and ascites, which are common adverse complications in cirrhosis, are not included in MELD. It has been suggested to incorporate a low serum sodium level into the prognostic model to enhance the predictive ability. Moreover, the change of MELD over time may provide updated information for patients on the transplant waiting list. In summary, although there was encouraging evidence supporting the prognostic advantage of MELD, the optimal role of MELD in the setting of outcome assessment for cirrhotic patients needs more study. Appropriate modifications and fine tuning of MELD are necessary for determining the ranking status of patients on the waiting list, to avoid a futile transplantation and improve overall patient survival.