Patient selection in an era of donor liver shortage: current US policy.

In the past, organ allocation in the US was based on anecdotal experience, self-interest and the opinions of single centers, with little support in the way of scientific evidence, mathematical survival modeling or validation. As organ transplantation became more successful, and as disparity between the number of patients on the waiting list and available organs became larger, a more justifiable donor allocation scheme became necessary. The current allocation scheme for donor livers is based on the model for end-stage liver disease/pediatric end-stage liver disease, which was introduced in 2002 by the United Network for Organ Sharing. This new allocation system has improved accuracy for predicting pretransplant mortality. In addition, the number of liver transplantations has risen for almost all etiologic categories, most noticeably for patients with hepatocellular carcinoma. Fewer patients have been registered on the liver transplant waiting list and fewer have been removed from the list because they have died or become too sick for transplantation. So far, this new allocation system has been a success, but it does have its shortcomings, and even with improvements to the system, the use of the donor organ pool still needs to be optimized.