The application of paired donation to live donor liver transplantation

The last decade has seen substantial growth and expansion of kidney paired donation (KPD), a modality by which pairs of incompatible live kidney donors and their intended recipients exchange kidneys such that compatible transplants result, both in the United States and internationally. In this issue of Liver Transplantation, 2 independent groups take this concept into the realm of live donor liver transplantation. At Queen Mary Hospital in Hong Kong, motivated by a high-urgency acute liver failure, Chan and colleagues matched 2 ABO-incompatible (ABOi) live donor pairs, and this resulted in 2 compatible and successful transplants. Hwang and colleagues describe 16 patients who underwent live donor liver transplantation in the first 6 years of their exchange program at the Asan Medical Center in Seoul. In the United States, deceased donor allocation in the Model for End-Stage Liver Disease era has been very successful in allocating livers to the sickest patients. In the example illustrated by Chan and colleagues, a patient in the United States with high-urgency acute liver failure would have a high likelihood of expeditiously receiving a deceased donor allograft. The balance between donor risk and reduced recipient waiting list mortality may account for the relatively low rate of live donor liver transplantation in the United States. As a result, incompatible donor/recipient pools in the United States are likely to remain small, and the impact of liver paired donation (LPD) in the United States is likely to be limited. This is contrasted with countries such as China, Korea, and Japan in which cultural or religious beliefs have resulted in low rates of deceased donation and a greater reliance on live donation to reduce recipient waiting list mortality. In these countries, the impact of LPD may be much more substantial. Although most of the logistics, ethics, and mathematics of exchanging organs have been developed in KPD, some of these concepts will need to be substantially modified for LPD. These include differences in the magnitude of donor and recipient risk, donor availability, blood type distributions resulting from the lack of human leukocyte antigen incompatibility, and poor results with the alternate modality, namely ABOi liver transplantation. Both groups nicely address some of these differences. Indeed, the risks to both the donor and the recipient involved in a live donor liver transplant exceed those of live donor kidney transplants by an order of magnitude. Furthermore, there is a greater chance of donor anatomical inequity in liver donation. In other words, the significant variation in the donor lobar size and venous, biliary, and arterial anatomy results in a greater differential in risk and success for both the donor and recipient operations versus kidney transplantation. Although in KPD there always exists the possibility that donors or recipients of different pairs will have differential outcomes, this possibility is more likely to occur and the difference is more likely to be substantial in LPD. Equity is more challenging, and the likelihood of having to back out of one of the operations is greater. As with all counseling for paired donation, it is critically important to counsel the donor that his intended recipient might have a poor outcome, whereas the actual recipient of his liver might have a good outcome or vice versa. At our institution, we counsel donors to embark on their paired donation