The idea that matching donor and recipient features ought to be a reasonable allocation policy is increasing among liver transplant programs, in particular in the era of extended-use donors (1–3). The best survival gain with a liver transplant (LT) may be achieved by allocating livers to patients who are most likely to be dropped from the list without a LT, but who also have the highest probability of survival after LT (3). The greatest transplant benefit may therefore be achieved by selecting the recipients on the waiting list and selecting the recipients according to the donors available.
The study recently published by our Center in the February issue of Transplantation showed how we managed the risk of drop-out due to tumor progression of patients with hepatocellular carcinoma (HCC) in the pre–Model for End-Stage Liver Disease (MELD) era. The old donors were more frequently allocated to patients with HCC and following this policy we reduced the drop-out rate of HCC patients and we improved the survival of marginal grafts after LT (4). The present study validated the idea that the match between the donor and recipient features improves the liver allocation policy.
On the other hand, as commented by Lucey (5), we do agree that these data should not be contrasted with the MELD allocation policy and we believe that the next issue will be how to allocate extended-use donors in the MELD era.
As reported in the United States, the MELD system provides the best selection of the recipients at the highest risk of dying on the waiting list (6). This policy has also been applied in our Center since March 2003 and after two years of experience, we significantly improved the patient survival on the waiting list (7).
We consequently believe that the selection of patients on the waiting list according to their MELD score improves the survival on the waiting list and it is a reasonable method of sharing livers between different transplant programs.
On the other hand, as stressed by Lucey, the weak aspect of this policy is that it does not consider the donor features: not all donors are appropriate for all recipients. An extended-use donor may work properly in one recipient and it may not work in another.
The challenge is therefore to calculate the ideal match between the donor and recipient features, which may offer the highest transplant benefit.
In the MELD era this policy could be applied, but we need to know the transplant benefit that every graft may give to every recipient.
When this data is available, we will select the recipient on the waiting list not only considering the recipient’s MELD score, but also evaluating the survival gain that the graft could offer to the patient.
An extended-use donor could therefore be allocated not to the first recipient on the waiting list, but to the second or third one, if they were presumed to have the highest transplant benefit. A simple example is reported in Table 1.
The transplant benefit depends on the risk of drop-out on the waiting list and on the risk of death after LT. These two variables are center-dependent (8–9), but a relevant role on the outcome of the patients on the waiting list and after LT is due to the recipient and donor’s clinical features and to the match between recipients and donors.
In conclusion, our future effort to further improve the liver allocation system is to produce a calculated risk of death after LT for each category of recipients and for each category of donors, which should be compared to the risk of death on the waiting list.
In this way, we will be able to select the best transplant benefit, but multicenter data are needed to achieve this aim.
Gian Luca Grazi
Antonio Daniele Pinna
Liver and Multi-organ Transplantation
University of Bologna, Italy
University of Bologna, Italy
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