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Towards a better liver transplant allocation system

We are pleased that the article by Ioannou has reported data to stimulate the debate on the balance between utility and justice in recipient prioritization and donor allocation in liver transplantation. The editorial by Marino covers many issues surrounding this, but we would like to point out some additional issues pertinent to the debate. First, the principal reason for the decreased death rate on the liver transplantation waiting list in the United States was a change in policy from allocating recipients on the basis of length of waiting time to placing the sickest patients first. The decrease in the death rate cannot be attributed to the use of the Model for End-Stage Liver Disease (MELD) scoring system per se because it is likely that the use of any one of a number of scores that measures severity of liver disease would have resulted in a similar outcome. Indeed, we have shown that the Child-Pugh and MELD scores are similar in predicting the 90-day mortality of patients on the waiting list, a finding recently confirmed by others. However, neither scoring system is suitable to predict mortality after liver transplantation. Thus, given the known importance of the donor in any transplant setting, but particularly in liver transplantation, it is reasonable—and we believe ethically correct—to consider liver transplantation outcomes when deciding who is to be transplanted. This involves consideration of both donor and recipient characteristics. Second, although Ioannou stated that his evaluation was the first large-scale and validated model predicting survival after liver transplantation, in January 2006, we published validated models that used the European Liver Transplantation Registry database. We used a training set of 21,605 first adult liver transplants and 8,489 in a validation set for 3-month mortality, and 18,852 and 8,313 patients, respectively, for 1-year mortality. Transplantations in this data set were undertaken in centers from 23 European countries; we did not exclude any patient on the basis of type of graft, serum sodium levels, or age. The decision to assess risk models for 2 separate early time periods after liver transplantation was made to capture mainly transplant-related factors for mortality (at 3 months) and to evaluate the early influence of recurrent disease on 1-year mortality, which has been a traditional time point to assess survival. As we stated, we fully concur that disease-specific models (along with donor characteristics) need to be developed because particular diseases recur that affect survival, such as hepatitis C and hepatocellular carcinoma. Moreover, donor characteristics (e.g., donor age and presence of hepatitis C virus [HCV]) affect recurrence of primary disease. Diseasespecific models are particularly important for mediumand long-term survival, as illustrated by the 5-year survival rate differences between HCV-positive and HCV-negative recipients described by Ioannou, whereas the 3-month and 12-month survival rates for HCV-positive or HCV-negative patients were very similar. Finally, we concur with both Ioannou and Marino that the liver transplant community must evaluate donor-recipient pairings in liver transplantation to determine the best balance between justice and utility. Ioannou has helpfully constructed donor risk models without cold ischemia time, but clearly this can be modified if organs from donors with marginal characteristics are collected. The risk for a particular recipient could be calculated in advance and could guide decision making. R. Wiesner (personal communication) has suggested that a degree of donor-recipient matching is occurring in the United States because approximately 70% of donor offers are not matched to the first recipient in line under the MELD system. It may be that the subsequent recipient who receives that donor does not differ much from the one who was first in line, except, for example, for an issue of body size. However, what is needed is data about what the outcomes are for the original donor–new recipient pairing, and more importantly, the original recipient–new donor pairing. The policy of prioritization of recipients in the MELD system is clear; what is needed is precise information on what actually happens. We believe that it is likely that analysis will confirm that donor-recipient matching is indeed occurring and is benefiting recipients. This is suggested by a recent article by Feng et al. We think that our published data and that of Ioannou can be used to assess these issues, as can the prevalence of formal delisting, which is an inevitable corollary of such donor-recipient