Summary report of a national conference: Evolving concepts in liver allocation in the MELD and PELD era. December 8, 2003, Washington, DC, USA

A national conference was held to review and assess data gathered since implementation of MELD and PELD and determine future directions. The objectives of the conference were to review the current system of liver allocation with a critical analysis of its strengths and weaknesses. Conference participants used an evidence-based approach to consider whether predicted outcome after transplantation should influence allocation, to discuss the concept of minimal listing score, to revisit current and potential expansion of exception criteria, and to determine whether specific scores should be used for automatic removal of patients on the waiting list. After review of data from the first 18 months since implementation, association and society leaders, and surgeons and hepatologists with wide regional representation were invited to participate in small group discussions focusing on each of the main objectives. At the completion of the meeting, there was agreement that MELD has had a successful initial implementation, meeting the goal of providing a system of allocation that emphasizes the urgency of the candidate while diminishing the reliance on waiting time, and that it has proven to be a powerful tool for auditing the liver allocation system. It was also agreed that the data regarding the accuracy of PELD as a predictor of pretransplant mortality were less conclusive and that PELD should be considered in isolation. Recommendations for the transplant community, based on the analysis of the MELD data, were discussed and are presented in the summary document.

Selection of pediatric candidates under the PELD system

1. The PELD score accurately predicts the 3 month probability of waiting list death for children with chronic liver disease. 2. Comparing pre and post PELD and MELD implementation, the percent of children receiving deceased donor livers increased and the percent of children dying on the list decreased after PELD/MELD implementation. 3. Excluding children transplanted at status 1, the largest percentage of children are transplanted at a PELD score < 10. 4. Before MELD/PELD 48% of all children receiving deceased donor organs were transplanted at status 1, compared to 41% in the PELD/MELD era. Wide regional variation occurs.

Selection of candidates with HCC for transplantation in the MELD era

1. Liver transplantation is the main option for patients with early HCC who are not optimal candidates for surgical resection. 2. Shortage of donors is its main limitation, as waiting for a liver allows the tumor to progress and induce exclusion from the waiting list and death. 3. The absence of randomized controlled trials hinders the establishment of the most effective therapy to prevent tumor progression while waiting. 4. Live donation may be a cost-effective approach if optimal results are expected and the mortality risk for the donor is kept below .3%. 5. Priority policies have to be developed and refined to provide a fair and effective distribution of cadaveric organs.

Increased expression of toll-like receptor 4 enhances endotoxin-induced hepatic failure in partially hepatectomized mice

BACKGROUND/AIMS

Liver failure associated with infections after hepatectomy remains a cause of mortality. It has recently been reported that toll-like receptor 4 (TLR4) is involved in recognizing lipopolysaccharides (LPS). The aim of this study was to investigate the role of TLR4 in endotoxin-induced liver injury after hepatectomy.

METHODS

C3H/HeN and C3H/HeJ mice underwent 70% hepatectomy or sham surgery, and LPS was administered 48 h after surgery. Expression of TLR4 mRNA, nuclear factor-kappaB (NF-kappaB) activation, tumor necrosis factor-alpha (TNF-alpha) and serum ALT levels, histological findings, and myeloperoxidase content were examined. Survival after LPS administration was also determined.

RESULTS

Hepatic expression of TLR4 was significantly increased 6-72 h after hepatectomy. In mice with endotoxemia after hepatectomy, hepatic NF-kappaB activation was greatly increased. Hepatic mRNA and serum levels of TNF-alpha, and ALT levels were significantly elevated compared with sham operated controls. Focal necrosis with neutrophil infiltration was apparent, which is consistent with increased myeloperoxidase contents in endotoxemia after hepatectomy in C3H/HeN mice. These were completely absent in C3H/HeJ mice. Survival of C3H/HeN mice with endotoxemia after hepatectomy was significantly lower than that of C3H/HeJ mice.

CONCLUSIONS

Upregulated TLR4 expression and function after hepatectomy plays a pivotal role in endotoxin-induced liver injury after hepatectomy.

Does MELD work for relisted candidates?

1. Based on OPTN data, the ability of the model for end-stage liver disease (MELD) to predict short-term pretransplant and posttransplant outcomes was assessed. 2. Concordance with pretransplant mortality was excellent. 3. Concordance with pretransplant mortality was better for candidates listed for a primary transplant. 4. Of the MELD components, there were no statistically significant differences in the effects on pretransplant mortality between candidates listed for a primary or a repeat transplant. 5. Concordance with posttranplant outcomes was poor.

Liver Function During Extracorporeal Whole Liver Perfusion in a Pig Model of Acute Ischemic Liver Failure

The shortage of livers for transplant has renewed interest in the potential of temporary liver support such as extra corporeal whole liver perfusion. In an ischemic induced liver failure model we perfused an extra corporeal liver through only a portal vein and assessed the function of this ex vivo liver by using hepatic tests to estimate elimination as well as synthesis capacities. Acute liver failure was performed in five control pigs by a hepatic devascularization associated to an end to side portocaval shunt. In a treated group, 5 to 6 h after this hepatic devascularization, animals were connected to an extra corporeal liver perfused via the portal vein with blood withdrawn from the ischemic liver animal from its portal vein. Devascularization of the liver induced an increase in liver enzymes and ammonia, a drop in the ratio of branched chain amino acids to aromatic amino acids, and a decrease in blood urea and indocyanine green and galactose clearances. In treated animals, urea, amino acid ratio, and clearances increased after the ex vivo liver perfusion. In this group, mean bile production and mean liver oxygen consumption were 13.7 +/- 3.6 ml/h and 16.1 +/- 7.7 ml/min, respectively. In an acute ischemic liver failure pig model, an extra corporeal whole liver perfusion demonstrated detoxification properties as well as synthesis capacities.

Synergistic effect of cold and warm ischemia time on postoperative graft outcome in human liver transplantation

BACKGROUND/AIMS

Prolonged cold ischemia time (CIT) during graft preservation and warm ischemia time (WIT) defined as a rewarming time have been reported to cause postoperative graft dysfunction after orthotopic liver transplantation (OLT). However, a synergistic effect of both CIT and WIT on patients of graft survival has not been confirmed. The aim of this study was to determine whether simultaneously prolonged CIT and WIT was associated with early graft outcome after clinical OLT.

METHODOLOGY

Between May 1997 and July 1998, 186 consecutive OLT cases were divided into 4 groups as follows: group A, CIT < or =12 hrs and WIT < or =45 min; group B, CIT >12 hrs and WIT < or =45 min; group C, CIT < or =12 hrs and WIT >45 min; and group D, CIT > 12 hrs and WIT >45 min. Liver graft survival within 90 days of OLT and early postoperative graft function were analyzed.

RESULTS

The graft loss rates were 5.4% in group A, 9.8% in group B, 11.1% in group C, and 42.9% in group D. The mean highest aspartate aminotransferase (AST) values after OLT in group D (3352.3+/-569.4 U/L) was significantly higher than those in groups A (1411.7+/-169.2 U/L) and B (1931.3+/-362.6 U/L).

CONCLUSIONS

The simultaneously prolonged cold and warm ischemia time significantly caused hepatic allograft injury and failure, suggesting some synergistic effects of CIT and WIT on postoperative graft function.

Pathophysiological effects of albumin dialysis in acute-on-chronic liver failure: a randomized controlled study

The pathophysiological basis of acute-on-chronic liver failure (ACLF) is unclear but systemic inflammatory response is thought to be important. In patients with ACLF, the molecular adsorbents recirculating system (MARS) improves individual organ function, but the effect of MARS on the proposed mediators of systemic inflammatory response is unclear. The present study was designed to determine the effect of MARS on the cytokine profile, oxidative stress, nitric oxide, and ammonia. A total of 18 patients with alcohol-related ACLF due to inflammation-related precipitants were randomized to receive standard medical therapy (SMT) alone, or with MARS therapy over 7 days. Plasma cytokines, malondialdehyde (MDA), free radical production, nitrate / nitrite (NOx), and ammonia were measured. Encephalopathy improved significantly with MARS (P < .01), but not with SMT. Mean arterial pressure and renal function remained unchanged. No significant change of plasma cytokines and ammonia levels were observed in either group. Plasma MDA levels did not change either. There was a fall in NOx (P < .05) with MARS, but not with SMT. In conclusion, in inflammation-related ACLF patients, albumin dialysis using MARS results in improvement of encephalopathy, independent of changes of ammonia or cytokines, without improving blood pressure or renal function. These results should temper the liberal use of MARS until further data is available.

Development and evaluation of an experimental model for investigating the pathogenesis and therapeutic strategies of acute liver failure

Because of the various etiologies of acute liver failure (ALF) a clinically relevant model must fulfill four criteria--reversibility, reproducibility, ALF-induced death, and a sufficient time interval for diagnosis and therapy between induction and death. In this study an experimental model was evaluated for these criteria. A total of 49 rats were randomized into seven groups: First, a pilot study was performed regarding the survival rate after different treatments: In group I, animals underwent a 70% liver resection. In group II, 70% liver resection was combined with ascending doses of postoperative endotoxin administration up to 400 microg/kg (group IIc). In group III, animals only underwent liver mobilization. In group IV, ALF was induced according to the protocol of group IIc, but with additional treatment of an endothelin-A-receptor (ETAR) antagonist. Animals in group V received only 400 microg endotoxin. After induction of ALF, all animals died within the first day, showing significantly elevated bilirubin and ammonium levels and severe damage to hepatocellular integrity. Application of the ETAR antagonist resulted in the survival of 6/7 animals until the 14th day; the biochemical and histomorphological changes were reversible. All other animals survived to the 14th day. A clinically relevant model of ALF in rats can be created by the combination of 70% liver resection and endotoxin application to produce an inflammatory component.

Inhibition of tumor necrosis factor-induced apoptosis in transgenic mouse liver expressing creatine kinase

BACKGROUND

The mitochondrion acts as a pivotal decision center in many types of apoptotic responses. To clarify the effects of the enhanced mitochondrial function on tumor necrosis factoralpha (TNFalpha)-induced apoptosis, we studied hepatic injuries in transgenic mice whose livers express creatine kinase (CK).

METHODS

Mice fed a diet containing 10% creatine, came to accumulate phosphocreatine and to enhance hepatic ATP levels and mitochondrial oxidative phosphorylation activities. TNFalpha-mediated hepatic apoptosis in normally fed and Cr-feeding CK transgenic mice were assessed.

RESULTS

TNFalpha and actinomycin D cause severe liver failure in normally fed transgenic mice, and in the wild-type mice. In contrast, no significant elevations in transaminase levels after injection were observed in Cr feeding transgenic mice. The disruption of the mitochondrial transmembrane potential at 2 h after TNFalpha injection, prior to ATP depletion, activation of caspase 3 like protease, and DNA fragmentation at 4-6 h after injection, were observed in normally fed transgenic mice. These were fully suppressed in Cr feeding transgenic mice. However, anti-Fas antibody-induced apoptosis was not inhibited in both groups.

CONCLUSIONS

The results indicate that TNFalpha-induced apoptosis was inhibited in CK transgenic mice livers by maintaining mitochondrial function.

Steatotic liver transplantation in the mouse: a model of primary nonfunction

BACKGROUND

The number of potential donor organs deemed suboptimal for transplantation because of hepatic steatosis is rising as the obesity rate increases. However, no mouse transplant model has been described within the framework of hepatic steatosis. We describe the development of and our initial experience with a steatotic mouse orthotopic liver transplant model using the ob/ob mouse. This model is technically achievable and functionally mimics primary nonfunction.

MATERIALS AND METHODS

Adapting techniques of a nonarterialized murine transplant model, C57BL6 ob/ob mice aged 5-7 weeks (26-35 g) and lean controls served as liver donors and recipients. Orthotopic liver transplantation (OLT) was performed using a two-cuff technique at the infrahepatic cava and portal vein. The suprahepatic cava was anastomosed end to end, and the bile duct was stented. The hepatic artery was not reconstructed.

RESULTS

Lean-to-lean OLT was performed with 70% (n = 10) long-term survival. ob/ob-to-age-matched lean recipients had 0% (n = 10) survival because of size discrepancy. ob/ob livers were transplanted to size-matched lean recipients (>3 months old) with short-term survival of 30% (n = 10). These mice survived the operation, awakened, but expired within 24 h. Serum transaminases revealed a significantly higher injury profile in the recipients of the steatotic livers, and histology showed massive centrilobular coagulative necrosis with hemorrhage, the overall picture being that of primary nonfunction.

CONCLUSIONS

This novel use of the ob/ob mouse for OLT provides us with a model for steatotic transplantation with primary nonfunction as the end point and may help to better understand the response of the steatotic liver to the insult of transplantation.

Portal and splenic hemodynamics in cirrhotic patients: relationship between esophageal variceal bleeding and the severity of hepatic failure

BACKGROUND

The relationship between portal and splenic vein hemodynamics, liver function, and esophageal variceal bleeding in patients with cirrhosis remains unclear. The aim of the present study was to investigate quantitative Doppler parameters of splanchnic hemodynamics in cirrhotic patients and to determine the value of the Doppler parameters in predicting esophageal variceal bleeding.

METHODS

With the help of pulsed Doppler ultrasonography, we investigated portal and splenic hemodynamics in 18 healthy controls and in 45 patients with liver cirrhosis, in whom the relationship of splenic hemodynamics with esophageal variceal bleeding and the grade of cirrhosis was examined.

RESULTS

Portal flow velocity was decreased in cirrhotic patients with Child's C cirrhosis, as compared to those with Child's A cirrhosis ( P < 0.001). The portal blood flow volume in Child's C cirrhosis were also significantly low compared to patients with Child's A and Child's B cirrhosis ( P < 0.001 and P < 0.05, respectively). There was a significant increase in the portal vein congestion index and splenic vein congestion index in patients with Child's C cirrhosis as compared to patients with Child's A cirrhosis ( P < 0.001). Among cirrhotic patients, the group with esophageal variceal bleeding had significantly greater splenic blood flow volume and splenic vein congestion index ( P < 0.001). Patients with ascites had significantly lower portal flow velocity ( P < 0.001) and higher portal vein congestion index and splenic vein congestion index ( P = 0.003 and P = 0.05, respectively) as compared to those without ascites.

CONCLUSIONS

In this report we have shown that the decrease in blood flow and increased congestion indexes in the portal vein and splenic vein are related to the impairment of liver function in cirrhotic patients; these indexes may be valuable factors for predicting esophageal variceal bleeding.

Contralateral portal vein embolization for hepatectomy in the setting of hepatic steatosis

Portal vein embolization is evolving as an important adjunctive tool in hepatic surgery. In select patients, preoperative hypertrophy of the future remnant liver via contralateral portal vein embolization decreases postoperative liver dysfunction. Hepatic steatosis is the most common liver parenchymal disorder in Western populations. Moderate and severe degrees of hepatic steatosis convey an increased risk of postoperative liver dysfunction following major hepatic resections, but no studies exist examining the role of preoperative portal vein embolization in patients with hepatic steatosis. In this manuscript, we review the indications for portal vein embolization currently supported by the literature and present a patient with moderate to severe steatosis who successfully underwent portal vein embolization and a subsequent major liver resection.

Model for end stage liver disease score predicts mortality across a broad spectrum of liver disease

BACKGROUND/AIMS

The utility of the model for end stage liver disease (MELD) score in non-transplant patients, particularly in those with less severe chronic liver disease remains uncertain. We studied and compared the predictive abilities of the MELD score and the Child-Turcotte-Pugh (CTP) score for intermediate (1-year) and long-term (5-year) mortality.

METHODS

One thousand six hundred and eleven patients with chronic liver disease were studied. Observed and predicted survival curves were plotted to evaluate the predictive ability of the MELD score for survival. Receiver operating characteristic (ROC) curves was used to compare the MELD and CTP score. A multivariable model was constructed to examine predictors of mortality.

RESULTS

The MELD score was a good predictor of 1-year mortality in chronic liver disease (c-statistics for all subgroups >/=0.75) and of 3- and 6-month mortality in alcoholic hepatitis (c-statistic >/=0.83). The CTP score had similar predictive abilities as the MELD. Hepatic encephalopathy was a strong independent predictor of death (Hazard ratio-2.8, P<0.0001).

CONCLUSIONS

The MELD score is a valid prognostic score for intermediate term mortality in a heterogeneous population with chronic liver disease although the CTP score is equivalent in predicting survival. Inclusion of hepatic encephalopathy adds additional prognostic value to the MELD score.

Plasma ghrelin concentrations, food intake, and anorexia in liver failure

Ghrelin is related to feeding behavior and nutrition in several physiological and pathological conditions. We tested the hypothesis that the anorexia and the decreased food intake of advanced liver failure might be associated with hyperghrelinemia. Fasting ghrelin was measured in 43 cirrhotic patients, food intake was self-assessed using the Corli score and a 3-d dietary record (n = 25), and anorexia/hunger was tested by a Likert scale. Fifty healthy subjects, matched for age and body mass index, served as controls. Ghrelin levels were not systematically increased in cirrhosis (414 +/- 164 vs. 398 +/- 142 pmol/liter in controls) but increased with decreasing Corli score (P = 0.014) and along the scale of anorexia/hunger (P = 0.0001), which were both related to the 3-d dietary record (P = 0.009 and P < 0.0001, respectively). Logistical regression confirmed that high ghrelin (>500 pmol/liter) was significantly associated with a low calorie intake [odds ratio (OR), 3.03 for any 100-calorie reduced intake; P = 0.015], a reduced Corli score (OR, 3.09; P = 0.031), and the anorexia score (OR, 3.37; P = 0.009), after adjustment for body mass index. The study confirms the previously observed relationship of fasting ghrelin with food intake in disease-associated malnutrition. In the presence of anorexia, hyperghrelinemia might indicate a compensatory mechanism trying to stimulate food intake, which is nonetheless ineffective in the physiological range.

Galactose elimination capacity as a prognostic marker in patients with severe acetaminophen-induced hepatotoxicity: 10 years' experience

BACKGROUND & AIMS

Patients with acetaminophen-induced fulminant hepatic failure may have the capacity for recovery if sufficient liver cell mass remains to allow regeneration. We investigated the prognostic potential of the galactose elimination capacity (GEC) as a noninvasive measurement of functioning liver cell mass in severe acetaminophen-induced hepatotoxicity.

METHODS

All patients admitted with acetaminophen poisoning during a 10-year period were studied retrospectively. A total of 220 patients who had at least one GEC performed were included in the study.

RESULTS

The GEC was lower in patients with than without hepatic encephalopathy (14.5 +/- 5.6 micromol/min/kg vs. 23.2 +/- 6.7 micromol/min/kg; P < 0.0001). Among patients with hepatic encephalopathy, the GEC was significantly higher in spontaneous survivors than in nonsurvivors (16.8 +/- 5.6 micromol/min/kg vs. 12.2 +/- 4.7 micromol/min/kg; P < 0.0001). In a logistic regression analysis, GEC was associated independently with mortality (odds ratio: 1.28 per 1 micromol/min/kg decrease in GEC; 95% confidence interval: 1.14-1.45). A threshold GEC of 16.5 micromol/min/kg to identify nonsurvivors had a sensitivity of 90%, a specificity of 72%, a positive predictive value of 49%, and a negative predictive value of 96%. None of 14 patients with hepatic encephalopathy and a GEC less than 10 micromol/min/kg survived.

CONCLUSIONS

The GEC was strongly associated with development of hepatic encephalopathy and death from acetaminophen-induced fulminant hepatic failure. The GEC was too unspecific to be used alone for identification of transplantation candidates, but it may be useful as a supplement to other selection criteria.

Elevated resistive index in the hepatic artery as a predictor of fulminant hepatic failure in patients with acute viral hepatitis: a prospective study using Doppler ultrasound

To assess the sensitivity and specificity of the resistive index of the hepatic artery, which is related to the vascular resistance of the artery, for the prediction of fulminant hepatic failure, we performed Doppler ultrasonography examinations on the hepatic arteries of 72 patients with acute viral hepatitis (25 of whom developed fulminant hepatic failure and 47 of whom recovered without developing fulminant hepatic failure) as well as the hepatic arteries of age- and sex-matched controls. The mean resistive index of the hepatic arteries in patients who developed fulminant hepatic failure was significantly larger than that of patients who recovered without developing fulminant hepatic failure (P < 0.01). When a resistive index cutoff level of 0.74 was used, an 84% sensitivity and a 94% specificity were obtained for the prediction of fulminant hepatic failure. An elevated resistive index of the hepatic artery may be useful for predicting the patient's clinical outcome and determining the need for a liver transplantation in patients with acute viral hepatitis.

Evaluation of effect of hybrid bioartificial liver using end-stage liver disease model

AIM: To study the role of hybrid bioartificial liver (HBL) in clearing proinflammatory cytokines and endotoxin in patients with acute and sub-acute liver failure and the effects of HBL on systemic inflammatory syndrome (SIRS) and multiple organ dysfunction syndrome (MODS).

METHODS: Five cases with severe liver failure (3 acute and 2 subacute) were treated with HBL. The clinical signs and symptoms, total bilirubin (TBIL), serum ammonia, endotoxin TNF-α, IL-6 and prothrombin activity (PTA), cholinesterase (CHE) were recorded before, during and after treatment. The end-stage liver disease (MELD) was used for the study.

RESULTS: Two patients were bridged for spontaneous recovery and 1 patient was bridged for OLT successfully. Another 2 patients died on d 8 and d 21. The spontaneous recovery rate was 30.0%. PTA and CHE in all patients were significantly increased (P < 0.01), while the serum TBIL, endotoxin,TNF-α, IL-6 were decreased. MELD score (mean 43.6) predicted 100% deaths within 3 mo before treatment with HBL. After treatment with HBL, four out of 5 patients had decreased MELD scores (mean 36.6). The MELD score predicted 66% mortalities.

CONCLUSION: The proinflammatory cytokines (TNFα, IL-6 and endotoxin)can be significantly removed by hybrid bioartificial liver and HBL appears to be effective in blocking SIRS and MODS in patients with acute and sub-acute liver failure. MELD is a reliable measure for predicting short-term mortality risk in patients with end-stage liver disease. The prognostic result also corresponds to clinical outcome.

Health status versus utilities of patients with end-stage liver disease

BACKGROUND

Health-related quality of life (HRQL) in patients with end-stage liver disease (ESLD) can be evaluated using either health-status questionnaires or utility assessment techniques. The two approaches have never been compared in terms of the values they assign to health prior to liver transplantation.

STUDY DESIGN

We assessed health status of patients with ESLD using validated disease-specific instruments covering multiple domains (measures of disease, psychological status, personal function, social/role function, and general health perception). We also elicited utilities using formal approaches (standard gamble [SG] and time tradeoff [TTO]) and a simpler alternative (visual analog scale [VAS]).

PATIENTS

Outpatients and inpatients at a single center prior to liver transplantation (n = 78).

PRINCIPAL FINDINGS

Health status was generally poor (median physical symptoms score on a 0-1 [worst to best] scale, 0.33; psychological symptoms, 0; happiness, 0.50; personal function, 0; social/role function, 0.40; and general health perception, 0.40). The median VAS score was 0.50. The median TTO was 0.79, indicating that half of the patients in our sample chose healthier life in return for a 21% shorter life expectancy. The median SG score was 0.50, indicating that half of the patients were willing to take up to a 50% risk of death in exchange for perfect health.

CONCLUSIONS

Both health status measures and utility assessments indicate that HRQL is compromised in patients awaiting liver transplantation. Despite the overall consistency between the two approaches, however, health status measures do not serve as reasonable proxies for utilities. For formal economic evaluations such as cost effectiveness analyses, only direct measures of utility can be used to quantify health states.

MELD and other factors associated with survival after liver transplantation

Allocation of cadaveric livers for transplantation in the United States is now based on the severity of illness as determined by the model for end-stage liver disease (MELD) score, a function of bilirubin, creatinine and international normalized ratio (INR). The aim of our study was to determine the association of various pre-transplant risk factors, including the MELD score, on patient survival after orthotopic liver transplantation (OLT). The medical records of 499 consecutive patients (233 female, 266 males, mean age 50.9 +/- 10.6 years) undergoing cadaveric OLT at our institution between June 1990 and February 1998 were reviewed. In the 407 patients alive at the latest contact, follow-up was 4.7 years, with a minimum of 20 months (maximum of 9.4 years). Variables considered for analysis included MELD score, age, pre-transplant renal dysfunction requiring dialysis, Child-Pugh classification, underlying liver disease, diabetes mellitus, and heart disease (ischemic/valvular/other). There were 92 deaths during follow-up. In univariate analysis, the MELD score, renal failure requiring hemodialysis pre-OLT, age > 42 years, and underlying etiology of liver disease were significantly associated with death during long-term follow-up. In multivariate models, age, underlying etiology of liver disease and renal failure requiring hemodialysis were independent predictors of death after OLT.