Personal Viewpoint: Navigating Challenges in Recipient Selection for End-Chain Kidneys.

As a result of the increasing number of transplants being facilitated by kidney paired donation, and newer initiatives such as voucher donation, end-chain kidneys now constitute a considerable proportion of kidney paired donation transplants in the United States. Data on end-chain kidneys are limited. They may be lower in quality compared to non-end chain living donor kidneys. However, they can provide unique opportunities for recipient candidates without living donors. There are no data or algorithms available to guide recipient selection for end-chain kidneys accepted by a transplant center. Considering the ethical principles of utility, justice, and respect for persons that underlie organ allocation, we discuss three potential approaches for recipient selection: 1) adherence to the Kidney Allocation System, 2) utility maximization and 3) priority to high-risk candidates, along with examples from our own center's experience. Similar considerations are also relevant to selection of recipients for non-directed donor organs, and to out-of-sequence allocation for deceased organ donors. Since end-chain kidneys represent an increasingproportion of kidney paired donation-facilitated living kidney donor transplantation in the United States, and will likely get more medically and surgically complex over time, ongoing research on their utilization and outcomes is needed.