Risky Business: Models of Risk in Transplant

Abstract

The rapid expansion of the kidney transplant waiting list has heightened the awareness of the transplant and medical community tooptimize the use of donor organs. Despitethis, donors at increased risk of infectious transmission organs, organs that may be suitable for transplantation, are being discarded at significant rates (1‐4). Donors at increased risk of infectious transmission organs are those organs deemed by the OPTN to result in an increased risk of infectious transmission. Increasing the utilization of such organs may increase the number of patients who are able to receive a timely transplant. However, the use of infectious risk donor (IRD) organs, a new term coined by the authors, has appropriately come under additional scrutiny since the transmission of HIV and HCV to four transplant recipients in 2007 (5). The use of these high risk organs brings with it a rare, but potentially devastating risk. Transplant physicians as wellaspatientsmustmakeaconsidereddecisionontherisk/ benefit of accepting such an organ despite the fact that the trade off of risk and benefit is not fully known. In addition, the transplant community must also be mindful of the impact of infectious transmission on the public perception of the organ supply which may ultimately affect organ donation. In this issue Chow et al. (6) present a Markov decision process model designed to aid physicians (and patients) in the decision to accept or decline donors at increased risk of infectious transmission kidneys based on the estimated survival after accepting versus declining the offer. The ultimate goal of the model is to increase the utilization of donors at increased risk of infectious transmission kidneys. The authors are to be commended for the development of thismodelandforacknowledgingthelimitations.However, there are several aspects that require further study and consideration that may complement the model developed. Further it is important to acknowledge that any model predicatedonestimatedriskofaseverebutrareevent,may easily under or over estimate the risk depending on the accuracy of the assumptions made and changes in prevalence or by pure bad luck. Although the empirical model does illustrate the efficacy of utilizing donors at increased risk of infectious transmission organs (given the assumptions made), the model does not account for behaviors associated with accepting and rejectingdonors at increasedrisk of infectioustransmission organs at the physician and patient level. Specifically it assumesthatphysiciansoperateasperfectdecisionagents on behalf of their patients and that they understand the relevantprobabilitiesandutilizethemoptimally.Inessence,