Recent data show approximately 15% of the United States population have chronic kidney disease (CKD), including almost 700 000 of whom are end-stage renal disease (ESRD); 70% of ESRD patients are currently on dialysis.1 Life expectancy and quality-of-life perspectives favor transplantation over dialysis as the preferred method of renal replacement therapy for those; and living donor transplantation has documented advantages over deceased donor transplantation. However, transplantation is expressly limited by the number of suitable organs available. Means of increasing the number of suitable, particularly living donor, kidneys are desperately needed. In this regard, Veale and colleagues2 provide in this issue of Transplantation a report of a novel concept whereby a person can donate a kidney now to initiate a chain as any altruistic, nondirected donor would3,4; but the donor in this concept is not nondirected. They are donating for a person at significant long-term risk of needing a transplant (eg, a person who has CKD or who has already undergone kidney transplantation). This person receives a voucher which is redeemable if/when transplantation becomes advisable, with the plan of becoming the chain-ending recipient of a future chain. As the authors note, informed consent of the donor and recipient is inherently paramount. These first 3 donations reported under this premise2 each initiated a chain, resulting in the transplantation of 25 recipients and saving untold patient-years on dialysis and/or the waitlist. To date, no voucher has been redeemed. Incentivizing these donors to donate when they did, as opposed to waiting until their directed recipient actually needs a transplant (or retransplant), was the concern that they might become unsuitable donors as they age. This concept introduces “chronological incompatibility” into the transplant lexicon.
As stated, the program “could…significantly increase the number of living donor transplants…”; that is certainly possible—perhaps probable. It is unlikely that all vouchers would be presented for redemption; even if so, it is a transplant volume-neutral program that still adds value by increasing living donor transplants. As intriguing as this extension of the National Kidney Registry’s Advanced Donation Program5 is, thoughtful questions emerge. It is unclear how 2 or more voucher holders would be prioritized with respect to one another as chain-ending recipients if each could end a future chain. The authors offer 2 possible factors to consider (highest panel reactive antibody, length of time holding a voucher), and both are arguably not individually or collectively sufficient. Should the number of transplants facilitated by the original donation(s) also be considered? This could (perhaps unfairly) advantage the recipient who held multiple vouchers—for example, the voucher holder in cases 2 and 3 in the article—and would incentivize more donors. Should HLA matching be an overriding factor? Should life-years from transplant matter? Time on dialysis? How about length of the future chain? The authors do note the current framework might not address all future situations; if the program becomes widely adopted, these potential situations become more likely and deserve proper forethought. The transplant community has long faced ongoing controversies over allocating a scarce resource, however, and these potential new challenges should not deter this program’s progress. Rather, they should be prospectively and transparently addressed by the proper stakeholders.
It is imaginable that currently underserved ESRD subpopulations are less likely to benefit from a voucher program, as the members of their family and/or social network may be prone to biological and/or psychosocial contraindications to living donation. Although this concern should also not constrain a positive development for others, it warrants considering ways to avoid widening the disparity between subpopulations and to ensure any benefit of a voucher program is as diversely realized as possible.
Should a voucher recipient receive additional deceased donor waitlist priority in the event they are not identified as a chain-ending recipient when the appropriate time arises? After all, they will have been the indirect (via their associated donor) source of a kidney that likely prompted multiple living donor transplants; and they would be getting an, on average, poorer quality kidney from the deceased donor list than their donor provided. If receiving waitlist priority, how long should they have been unable to match on a living donor chain before receiving it? These are points to consider in incentivizing donors to participate.
Who constitutes an appropriate future voucher recipient? Should only patients with stage 3 or higher CKD be allowed to bring forth a potential donor(s)? Should the directed voucher recipient undergo transplant evaluation now? If so, who pays for this, and when? The evaluation might expose a contraindication to transplantation that would otherwise not be apparent until later, with obvious implications on their associated donor’s willingness to donate now. Disappointment, at the least, would ensue if a person donated and a recipient contraindication was eventually identified, particularly if it was discoverable at the time of donation.
Any organ donation-enhancing initiative, especially one that enhances living kidney donation like this one, is to be commended. The above unanswered questions, some more hypothetical than others (and some not exclusive to this initiative), are not an exhaustive list of potential challenges facing this nascent program. Readers and experience will surely identify more. Despite these potential challenges, the program's potential merits for ESRD patients are undeniable; meeting these challenges could increase national kidney transplant volume with higher-quality organs, decrease the number of waitlisted candidates, shorten candidate waiting times, decrease waitlist mortality, and improve overall outcomes after transplantation. Financial benefits would be inevitable. Again, the importance of informed consent of donor and potential recipient cannot be overstated, and prospective and transparent discussions among the appropriate organizations on how to best evolve from here are advisable.
1. United States Renal Data System. 2016 USRDS annual data report: epidemiology of kidney disease in the United States. https://www.usrds.org/2016/view/Default.aspx
. Published 2016. Accessed March 28, 2017.
2. Veale JL, Capron AM, Nassiri N, et al. Vouchers for future kidney transplants to overcome 'chronological incompatibility' between living donors and recipients. Transplantation
3. Rees MA, Kopke JE, Pelletier RP, et al. A nonsimultaneous, extended, altruistic-donor chain. N Engl J Med
4. Butt FK, Gritsch HA, Schulam P, et al. Asynchronous, out-of-sequence, transcontinental chain kidney transplantation: a novel concept. Am J Transplant
5. National Kidney Registry. Living donors. http://kidneyregistry.org/living_donors.php?cookie=1#advanced
. Published 2017. Accessed March 28, 2017.