The pediatric end-stage liver disease (PELD) score

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1 Selection of Pediatric Candidates Under the PELD System Sue V. McDiarmid, 1 Robert M. Merion, 2 Dawn M. Dykstra, 2 and Ann M. Harper 3 Key Points 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 < 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. The pediatric end-stage liver disease (PELD) score and the model for end-stage liver disease (MELD) for adults were developed simultaneously to create an integrated system of deceased donor liver allocation based on the severity of chronic liver disease. 1,2 The MELD and PELD scores rank children and adults alike on a single liver waiting list according to their probability of death within 3 months of listing. The PELD score was derived from a population of children enrolled in the Studies of Pediatric Liver Transplantation (SPLIT) database. 3 Similar underlying principles were used to develop the PELD and MELD scores. The parameters tested for inclusion in the models were required to be objective and measurable, and the same statistical method (area under the receiver operator curve) was used to test the accuracy of the models. From multivariate analyses of the SPLIT population, factors included in a model that predicted death, or death and / or moving to the intensive care unit (ICU) within 3 months of listing, were: international normalized ratio, total bilirubin, serum albumin, age 1 year, and height 2 standard deviations from the mean for age and gender. The PELD score derived from this model was highly accurate in predicting both death and death / moving to an intensive care unit within 3 months of listing, with a receiver operating characteristic of 0.92 and 0.82, respectively. In addition, the PELD score was validated as an accurate predictor of death on the waiting list in a separate population of children at a large single center (receiver operating characteristic 0.89). 4 The PELD equation is shown in Table 1. The PELD and MELD scores are derived from distinctly different equations. The factors included in MELD score calculation are bilirubin, international normalized ratio, and serum creatinine. As well, the populations in which the scores were developed were different. 5,6 As shown in Figure 1, the MELD curve and the original SPLIT-derived PELD survival curve that predicted survival 3 months after listing for transplant were clearly separate. For any given numerical score, children as compared to adults had a lower probability of dying awaiting liver transplantation. These differences were recognized and discussed prior to implementation of MELD and PELD by the pediatric and adult liver transplant community. In order to implement PELD and MELD, the following (somewhat arbitrary) decisions were made: 1. The numeric value of the PELD score would be used, unadjusted for the difference in probability of death for children and adults with the same score. 2. Unlike the MELD score, the PELD score would not be capped at 40 and neither would the minimum value be set at The status 1 assignation for children with severe chronic liver disease, meeting certain criteria, would be retained. 4. Pediatric donors ( 18 years of age) would continue to retain some priority for allocation to pediatric patients. 5. Regional review boards, at their discretion, could assign additional points, or an upgrade to status 1, for Abbreviations: PELD, pediatric end-stage liver disease; MELD, model for end-stage liver disease; SPLIT, Studies of Pediatric Liver Transplantation; SRTR, Scientific Registry of Transplant Recipients; OPTN, Organ Procurement and Transportation Network. From the 1 Departments of Pediatrics and Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA: the 2 Scientific Registry of Transplant Recipients / University Renal Research and Education Association, Ann Arbor, MI; and the 3 Departments of Research Allocation Policy, United Network of Organ Sharing (UNOS), Richmond, VA. Presented at the AASLD / ILTS Transplant Course, October 29, 2004, Boston, MA. Address reprint requests to S. V. McDiarmid, M.D., UCLA Medical Center, Rm MDCC, Le Conte Ave., Los Angeles, CA smcdiarmid@mednet.ucla.edu Copyright 2004 by the American Association for the Study of Liver Diseases Published online in Wiley InterScience ( DOI /lt Liver Transplantation, Vol 10, No 10, Suppl 2 (October), 2004: pp S23 S30 S23

2 S24 McDiarmid et al. Table I. Pediatric End-Stage Liver Disease (PELD) Scoring System PELD Score (Age ( 1 YR.)) Log e (albumin g/dl) Log e (total bilirubin mg/dl) 1.87 Log e (INR) (Growth failure ( 2 Std. Deviations present)). Notes: Laboratory values less than 1.0 will be set to 1.0 for the purposes of the PELD score calculation. Growth failure will be calculated based on age and gender using the current CDC growth chart. Scores for patients listed for liver transplantation before the patient s first birthday continue to include the value assigned for age ( 1 Year) until the patient reaches the age of 24 months. patients whose calculated PELD or MELD score was judged not to reflect their urgency for transplantation. A major concern of the pediatric liver transplant community at the time of implementation of MELD and PELD, was that under the new allocation policy, children would have a reduced access to transplantation, particularly as children on the waiting list are outnumbered 17 to 1 by adults, a discrepancy which continues to increase. 7 A particularly vulnerable group of children are those under 2 years of age, especially those less than 1 year of age, for whom the highest death rate on the waiting list has been consistently reported in the OPTN/SRTR Annual Reports. 8 Finally, it was unclear how the insertion of a large population of adult patients with hepatocellular carcinoma, with an assigned minimum MELD score of 24 (and the opportunity for incremental increases in the score every 3 months), would affect children within the same numeric severity score ranges. This review addresses how the MELD/PELD allocation system has selected children for transplantation, including comparisons between the pre- and post- MELD/PELD eras and regional differences. Reasons for removal from the waiting list and current rates of both transplantation and death on the waiting list are compared for children and adults. An analysis is presented of children transplanted at status 1, and the effect on donor allocation of retaining status 1 for children with chronic liver disease and by exception. The impact of the new policy for pediatric donor allocation to pediatric recipients is compared to the pre-meld/ PELD era, and broader sharing of pediatric donors is discussed. Finally, we addressed whether the concept of the benefit of transplantation, as measured by years of life gained with or without transplant, should be incorporated into allocation policies for children. Further Validation of PELD in the Organ Procurement and Transplantation Network (OPTN) Database The implementation of PELD (and MELD) has allowed for ongoing analyses of the accuracy of PELD to predict survival on the waiting list under the new allocation policy, as opposed to the survival curve generated retrospectively from the SPLIT database. Figure 1 shows how the original curve derived from the SPLIT database, which predicted survival by PELD score 3 months after listing, has changed with the implementation of MELD/PELD. For comparison, the most recent MELD curve is also shown. Note that for a severity score of 0 to 25, children, in comparison to adults, now have a lower probability of survival 3 months after listing. This is in contrast to the original SPLIT-derived curve that predicted children always had a higher chance of survival at any give score. Above a severity score of 25, the PELD curve moves to the right of both the MELD curve and the original SPLITderived PELD curve, indicating that in this higher score range, children have a better chance of survival waiting for transplant as compared to adults. Effect on Liver Waiting List: Comparing Preand Post-MELD/PELD Eras An analysis was performed comparing the percentage of adults and children removed from the liver transplant waiting list (for reasons of deceased donor transplant, Figure 1. Predicted probability of waiting survival at 3 months by severity scores. Curves are shown for the MELD score (as of June 2004), PELD score (as of June 2004), PELD (as of June 2004) removing 8 children with outlier PELD scores between 50 and 90, and PELD curve from the original SPLIT database. Source: SPLIT and SRTR analyses, June 2004.

3 Selection of Pediatric Candidates Under PELD S25 Figure 2. Reasons for removal from the liver waiting list before and after implementation of MELD/PELD. Source: SRTR analysis, February 27, 2001 to February 26, 2002 (pre) and February 27, 2002 to March 31, 2004 (post) MELD/PELD. death, too sick to transplant, living donor transplant, or other ), 1 year before, and 1 year after MELD/PELD implementation. Figure 2 shows this comparison for both adults and children for the pre-meld/peld era (February 27, 2001, through February 26, 2002) and the post-meld/peld era (February 27, 2002, through February 26, 2003). In the pre-meld/peld era 9,909 adults and 1,035 children were added to the list, in comparison to 8,751 adults and 856 children in the 1st year after implementation. In the MELD/PELD era, the percentage of deceased donor transplants increased from 49% to 53%, compared to a 2% increase for adults. Importantly, for both children and adults, the percentage of patients who died on the liver waiting list decreased between the pre- and post- MELD/PELD eras. The utilization of living donors decreased for both adults and children after implementation of MELD/PELD, and removals from the list for other reasons increased for both age ranges. These initial data suggested that the access to deceased donors for both children and adults had not been adversely affected by the change in allocation policy, and that overall death on the waiting list was reduced. 90-Day Outcomes on the Liver Waiting List As both the MELD and PELD scores rank patients according to their probability of death 3 months after listing, outcomes of patients 90 days after listing is a relevant time point for assessment of the policy s effect. Table 2 shows the relative rates of death, and deceased donor transplant, at 90 days after listing for both adults and children added to the liver-only waiting list between February 27, 2002 and December 31, The results are shown both as an aggregate, and within ranges of the calculated PELD and MELD scores. Comparing 14,272 adults to 896 children 90 days after listing, and excluding status 1 and exceptional cases, the rate of deceased donor transplantation for children was higher (37.8%) than for adults (24.7%). The death rates were similar: 8.3% and 8.2% for children and adults, respectively. PELD Scores at Listing and at Transplantation Figure 3 shows the percentage of children within ranges of the match PELD score at the time of listing and at the time of transplantation for the time period February 27, 2003, to March 31, Note that the largest percentage of children were transplanted at a PELD score 10. Figure 4 shows the percentage of patients transplanted within MELD/PELD (match score) ranges, comparing children and adults. Only 5.8% of adults were transplanted at a score of less than 10 compared to 34.4% of children. Table 3 shows the mean calculated and match PELD scores at listing by age. The youngest children, those 1 year of age, had substantially higher PELD scores at listing and transplant than older children. Across the 11 OPTN regions, there is considerable variation between the PELD scores at listing (range:

4 S26 McDiarmid et al. Table Day Transplant and Mortality Rates After Waitlisting for Liver (only), by Calculated MELD/PELD Lab Score New Listings Between 2/27/02 and 12/31/03 Calculated Score N Mean Lab (Match) Score Death Rate* Median Lab MELD/PELD at Death Transplant Rate Median Lab MELD/PELD at Transplant Adult Status % % 34 MELD: Lab (No Exceptions) , % % , % % , % % % % % % 37 All 14, % % 22 MELD:HCC HCC % % 24 HCC % % 29 All 1, % % 29 Other Exceptions Adult (26.9) 11.7% % 25 Pediatric (30.8) 2.4% % 32 Pediatric Status % % 23 PELD: Lab (No Exceptions) ( 11) ( 1) % % % % % % % % % % % % 43 All % % 16 *Censored at removal from the waiting list for reasons other than death. Censored at removal from the writing list for reasons other than cadaveric transplant. Table 3 shows the 90 day outcornary the MELD/PELD distribution for all patients including the average MELD/PELD score at death and transplant. The study population includes all patients on the liver waiting list (excluding liver-intestine candidates) that were added between 2/27/02 and 12/31/03. All patients were followed for 90 days from the start date. Non-Status 1 patients granted an exception within 30 days of date of listing had the exception score used for calculation of their match MELD/PELD. The first exception MELD/PELD score within 30 days of listing was used for calculating the match MELD/PELD score; follow-up time began on the exception date. Start date for patients with default assignment of MELD/PELD-6 was delayed for up to 30 days if an updated score became available during this time. Unadjusted Cox regression models were used to model 30-day rates of transplantation and death on the waiting list. Figure 3. Percentage of children listed and transplanted at allocation (i.e., match) by PELD score ranges. Source: SRTR analysis, February 27, 2002 to March 31, Figure 4. Percentage of children and adults transplanted at allocation (i.e., match) score ranges. Source: SRTR analysis, February 27, 2002 to March 31, 2004.

5 Selection of Pediatric Candidates Under PELD S27 Table 3. Mean and Median Lab PELD at Listing by Age and Previous Transplant Categories Mean PELD Median PELD Age at listing 1 Year Years Years Years Previous liver transplant No Yes Source: OPTN/SRTR Data as of May Includes all non-status 1 listings between 2/27/02 and 3/31/ ) and at transplant (range: 7-24; Fig. 5). Some of the variation can be explained by the small numbers of children transplanted in some regions. Deaths on the Waiting List Children 2 years of age, particularly those 1 year of age, have previously had the highest mortality on the waiting list compared to any other age group. 8 Death on the liver waiting list, adjusted for time waiting on the list (per 1,000 patient years), was compared for 12 months before and the 25 months after implementation of MELD/PELD. As shown in Figure 6, the implementation of MELD/PELD has reduced the high death rates of children 2 years of age. The Effect of Status 1 for Children Unlike adults, children with chronic liver disease meeting specific criteria can be listed at status 1. In addition, children (and adults) can be granted status 1 by exception after prospective approval by their regional review Figure 6. Death adjusted per 1,000 patient years on the liver waiting list before and after implementation of MELD/PELD. Source: SRTR analysis, February 27, 2001, to February 26, 2002 (pre) and February 27, 2002 to March 31, 2004 (post) MELD/PELD. board. A recent analysis of the OPTN database examined the percent of children transplanted at status 1, comparing 18 months before and after implementation of the MELD/PELD policy. 9 As shown in Figure 7, 48% (n 339) of all children who received deceased donor grafts were status 1 before MELD/PELD, compared to 41% (n 306) after MELD/PELD implementation. Of these, 23.3% and 29.7% were transplanted at status 1 by exception in the pre- and post- MELD/PELD eras, respectively. The percent of children at status 1 who received a living donor was similar between the eras: 8.6% and 10.3% for pre- and post-meld/peld, respectively. The percent of children transplanted at status1 showed wide variation between regions, ranging from as low as 7% to as high as 75%. Those transplanted at status 1 by exception ranged from 2.5% to 43.3% between regions. Biliary atresia was the diagnosis of about 1 of 3 children transplanted at status 1, irrespective of era. Table 4 shows Figure 5. Mean PELD score at listing and at transplant by region. Source: SRTR analyses, February 27, 2002 to March 31, Figure 7. Percentage of children transplanted at status 1: total compared to by exception, pre- and post-meld/ PELD. Source: OPTN analysis.

6 S28 McDiarmid et al. Table 4. Diagnosis for Children Transplanted at Status 1: Pre vs Post PELD Diagnosis PRE POST Acute Hepatic Necrosis 10.6% 21.1% Biliary Atresia 33.2% 32.4% Cholestatic Liver Disease/Cirrhosis 4.8% 4.3% Malignant Neoplasms 2.5% 5% Metabolic Disease 9.6% 9.4% Non-Cholestatic Cirrhosis 10% 8.2% Other 13.8% 12.8% Other Liver Disease 15.3% 14.4% the diagnostic categories of children transplanted at status 1. There was a significant difference between the mean calculated PELD scores for children with fulminant liver failure (PELD 24.6), those with chronic liver disease meeting standard criteria for Status 1 (PELD 19.6) and for those children listed by exception, (PELD 14.0; P.001). Death rates were examined for the ranges of PELD score and the different categories of status 1 for children: fulminant liver failure, primary nonfunction / hepatic artery thrombosis, chronic liver disease with PELD 25, chronic liver disease with PELD 25, and status 1 by exception, for children added to the waiting list from February 27, 2002, to September 30, The death rate was calculated by dividing the number of deaths in each category by the total number of patient years in each category. The results (Table 5) show that children with fulminant liver failure, primary nonfunction / hepatic artery thrombosis, and those with chronic liver failure (meeting criteria for status 1 and PELD 25) had similar and substantially higher death rates than children with chronic liver disease and Table 5. Death Rates/1000 Patient Years for Different Status 1 Categories Status 1 Category #of Patient Years Death RAte Median Lab PELD Fulminant 5.9 (24) PNF/HAT 3.0 (12) Other (All) 5.6 (17) Other (lab PELD 25) 1.5 (7) Other (lab PELD 25) 4.1 ( Exception 3.9 (2) Figure 8. Patient (A) and graft (B) pre- and post-meld/ PELD implementation, for children, comparing: overall survival, status 1 meeting standard criteria, status 1 by exception, and non-status 1. Source: OPTN analysis. PELD 25, and particularly those children listed at status 1 by exception. Six-month patient and graft survival was compared for all children transplanted, those meeting status 1 standard criteria, those transplanted at status 1 by exception, and those transplanted at non-status 1 (Fig. 8A and B). No significant differences between each of the groups or when comparing the pre- and post- MELD/PELD eras were seen. Pediatric Donors Allocated to Pediatric Recipients The implementation of MELD/PELD required a change in the previously established policy that allowed preference for pediatric aged donors ( 18 years) to be allocated to pediatric recipients within each of the 4 status definitions, following the local, regional and national algorithm. Under MELD/PELD, within the population of adults and children with a MELD or PELD score predicting a greater than 50% probability of death within 3 months of listing (a MELD of 32 and a PELD of 46, respectively) a pediatric donor would 1st be allocated to a pediatric patient and then allocated to an adult patient within this range. If the pediatric donor was not placed, it would then be allocated first to a child

7 Selection of Pediatric Candidates Under PELD S29 Figure 9. Percentage of pediatric donors allocated to recipients by age range, comparing pre- and post-meld/ PELD eras. Source: SRTR analysis, February 27, 2001, to February 26, 2002 (pre) and February 27, 2002, to March 31, 2004 (post) MELD/PELD. in the population of patients with a less than 50% probability of death within 3 months of listing. The age of recipients of pediatric donors for 1 year prior to implementation of MELD/PELD was compared to 1 year after implementation. As shown in Figure 9, regardless of era, the majority (50%-60%) of pediatric donors were allocated to adults. Comparing the 2 eras, there was a small decrease in the number of pediatric donors allocated to adults in the post-meld/ PELD era and a small increase in the number of pediatric donors transplanted into children 2 years of age. Discussion Comparing time periods before and after the introduction of MELD/PELD, a similar percentage of children are being transplanted, the death rates for children listed are lower, and transplant outcomes are similar. These findings are in agreement with results reported for adult patients. 10 While these results reassure that access for children to transplantation and outcome after transplant have not been adversely effected by the new allocation policy, a closer analysis of the results suggest improvements in the system are warranted. Most obvious is the uneven allocation of donor livers across the PELD score ranges, with 2 extremes evident. Almost half of all children are transplanted at status 1, and of the remainder, half again are transplanted at PELD score 10. Are we transplanting too many children at status 1, and are too many children transplanted too early? Within the status 1 category, only a minority of children have acute liver failure, primary nonfunction, or hepatic artery thrombosis. Most have either chronic liver disease or enter status 1 by exception, The observation that almost1/3ofchildren are listed by exception, and have a low probability of death on the waiting list in comparison to any other status 1 subset, suggests that the status 1 by exception designation should be reconsidered. Continuing to allow children listed at status 1 by exception (1 / 3 of all status 1 children) to compete equally for organs with other status 1 children, and with adults either at status 1 or having very high MELD scores, all of whom have substantially higher death rates, contravenes the Department of Human Health Services mandate 11 that priority should be given to transplanting the patient with the highest probability of dying 1st. As well, adults or children with high MELD/PELD scores can be bypassed in favor of a status 1-listed child with a much lower probability of dying while waiting. It is also important to note, that within the chronic liver disease group, only children with a PELD score 25 have a similar death rate on the list compared to those children with acute liver failure. Redefinition of status 1 for children is being considered. Current suggestions include: prioritizing children with acute liver failure (including primary nonfunction and hepatic artery thrombosis) above any other status 1 child; stricter definition of the status 1 chronic liver disease criteria, including a threshold PELD of 25; and eliminating the status 1 by exception category altogether. On the other end of the spectrum, too many children appear to be transplanted too early. Preliminary Scientific Registry of Transplant Recipients (SRTR) analyses (Robert M. Merion, personal communication) suggest that children transplanted at a PELD score 10 have a higher probability of death after transplantation as compared to remaining on the list. While the numbers are admittedly small in the current analyses, this trend needs to be carefully followed. The allocation of livers to children with a low probability of dying on the list may be the result of 2 factors: the large number of children transplanted at status 1, and the difficulty of placing small-sized pediatric donor livers into recipients following the local first, then region, allocation algorithm. When a liver from a small pediatric donor is not transplanted into a status 1 child, the remaining number of children listed in the local area may be quite small. As a result, the next offer may go to the only size-matched, ABO blood group identical child available locally, even if the PELD score is low, although other sicker children with higher PELD scores and of a similar size are still waiting in the region. Regional sharing of pediatric donors, along with stricter definitions of status 1 may improve this allocation inequity.

8 S30 McDiarmid et al. Analyses done by the SRTR of regional sharing of pediatric donors (age 18 years), which model the effect on both children and adults, show that although there is a small increase in the number of children transplanted, as well as a small decrease in the number of children dying on the list, there is no substantial change in the number of deaths for waiting adults. 12 By preserving the definition of donor age at 18 years, this policy, if put into effect, would have the added benefit of potentially encouraging the use of split-liver transplantation. The recent approval of a policy for regional sharing of adult donors to recipients with a MELD/PELD score 15 is being integrated into a proposal for the regional sharing of pediatric donors. This will be important to protect access of children, especially small children, to transplantation. The way in which the PELD score selects pediatric patients for transplant does not seem to have changed overall patient and graft survival. This is supported by other studies that have shown that in multivariate analyses the PELD score at transplant has no statistically significant effect on posttransplant patient and graft survival at 6 months. The concept of transplant benefit has not yet been well studied in children. In adult liver transplantation, the benefit of transplantation, as measured by the life years gained with or without transplantation, is being considered as a principle for liver allocation for adults. 13 Adults transplanted with a MELD score 17 have a statistically important decrease in life years gained if transplanted as compared to remaining on the waiting list. 14 As noted above, although a similar effect was seen for children transplanted at a PELD score 10, the pediatric transplant community has been cautious about adopting a policy that would preclude access to liver transplantation for these children. Not only were the numbers small in the analyses, but pediatric hepatologists have long held the opinion that the benefit of transplantation for children should not be limited to survival as the only relevant outcome. The benefit of transplantation on growth, 15 development, future cognitive function, and overall quality of life should not be discounted. At present, the difficulty lies in defining transplantation benefits other than survival, developing the appropriate measures of these benefits, as well as the required data collection to allow appropriate models to be constructed. Developing such models is a priority on the agenda of the SRTR. In conclusion, the current allocation policy is preferentially selecting for transplant a large number of status 1 listed children 1st, followed by children with the lowest probability of death on the list. These 2 opposing extremes have had the net effect of protecting the pediatric liver transplant candidate s access to transplantation and of preserving posttransplant outcomes. However, redefining status 1, combined with broader sharing of pediatric donors, should result in improved equity for access to deceased donor livers for both children and adults awaiting liver transplantation. References 1. Wiesner RH, McDiarmid SV, Kamath PS, Edward EB, Malinchoc M, Kremers WK, et al. MELD and PELD: application of survival models to liver allocation. Liver Transpl 2001;7: Freeman RB Jr, Wiesner RH, Harper A, McDiarmid SV, Lake J, Edwards E, et al. The new liver allocation system: moving toward evidence-based transplantation policy. Liver Transpl 2002;8: McDiarmid SV, Anand R, Lindblad A. Development of a pediatric end stage liver disease score to predict poor outcome awaiting liver transplantation. Transplantation 2002;74: Mazariegos GV, Anand R, McDiarmid SV. Validation of PELD severity score in a pediatric transplant candidate database. Am J Transplant 2002;2: Kamath PS, Wiesner RH, Malinchoc M, Kremers W, Therneau TM, Kosberg CL, et al. A model to predict survival in patients with end-stage liver disease. Hepatology 2001;33: SPLIT Research Group. Studies of pediatric liver transplantation (SPLIT): year 2000 outcomes. Transplantation 2001;72: McDiarmid S. New liver allocation policies and their potential effect on pediatric patients awaiting liver transplantation. Pediatr Transplant 2002;6: HHS / HRSA / OSP / DOT, UNOS, and URREA OPTN / SRTR annual report McDiarmid SV, Harper AM. Are too many pediatric liver recipients transplanted at status 1? Am J Transplant 2004;4(Suppl 8). 10. Freeman RB, Wiesner RH, Edwards E, Harper A, Merion R, Wolfe R. Results of the first year of the new liver allocation plan. Liver Transpl 2004;10: Organ Procurement and Transplantation Network-HRSA. Final rule with comment period. Fed Regist 1998;63: Goodrich NP, McCullough KP, McDiarmid S, McDonald RA, Rodgers AM, Harmon, et al. Simulation modeling of regional sharing in pediatric donor liver allocation. Am J Transplant 2004;4(Suppl 8). 13. Olthoff KM, Brown R, Delmonico F, Freeman R, McDiarmid S, Merion, et al. Summary report of a national conference: evolving concepts in liver allocation in the MELD/PELD era. Liver Transpl 2004;10(suppl 2):A6 A Merion RM, Schaubel DE, Dykstra DM, Freeman RB, Port FK, Wolfe RA. The survival benefit of liver transplantation. Am J Transplant 2004;4(Suppl 8): McDiarmid SV, Gornbein JA, DeSilva P, Goss JA, Vargas JH, Martin MG, et al. Factors affecting growth after pediatric liver transplantation. Transplantation 1999;67: