Fair Kidney Allocation Based on Waiting Time

We study the allocation of cadaveric donor kidneys for transplantation based merely on waiting time. Despite the first impression, this simple allocation rule turns out to possess very attractive ethical and medical properties. Current allocation rules do not consider criteria such as sex, age and race perhaps for fear of morally unacceptable allocations, although certain combinations of these criteria are known to affect graft survival rates. We demonstrate that allocation by waiting time automatically protects disadvantaged patient types and puts them in a near to optimal position. The inclusion of sex, age and race will therefore not lead to morally unacceptable allocations. This allows individual patients to improve the expected survival time of their graft relative to the status quo without being penalized by the allocation rule. Moreover, decisions about when to start compromising on expected graft survival rates in favour of shorter waiting times are made locally by patients and their medical advisers rather than by a centralized protocol.