When my economist colleagues and I started to assist transplant professionals in organizing kidney exchange over a decade ago.1 Many people—both physicians and economists—were surprised by the collaboration. But it should not have been so surprising, because economics is about cooperation, coordination, competition, and exchange—and so is transplantation.
Transplantation involves cooperation between donors and patients, and coordination between organ procurement organizations and transplant centers. It involves competition among hospitals for patients, and between transplantation and other uses of scarce public and private resources. It also involves exchange and gift giving, from the dead to the living and among the living.
The connection between economics and transplantation is even clearer if we look at economics from the perspective of market design, a part of economics that sometimes lets us repair markets or make new ones. Kidney exchange (also called kidney paired donation) makes these connections especially clear.
Noneconomists sometimes find it strange to think of kidney exchange as a market, because in almost all countries, it is illegal to buy or sell organs. However, there are many markets in which money does not decide who gets what. For example, it’s expensive to attend an American medical school, but the ability to pay is not sufficient—a prospective student has to be admitted. Similarly, prospective employees cannot simply choose where to work; they have to be hired. Admissions to competitive schools, and labor markets, are matching markets, in which you cannot just choose what you want; you also have to be chosen.
Kidney exchange is a matching market in which kidneys are not bought and sold, but in which exchange makes transplants accessible even to incompatible patient-donor pairs.
I will review some of the progress kidney exchange has made, and some challenges it now faces. Then I will discuss ideas for extending the reach of kidney exchange, and other ways to increase both deceased and living organ donation.
As far as I know, kidney exchange was first discussed by Rapaport,2,3 and the first kidney exchange was performed in the 1990s in South Korea,4 while the first kidney exchange in the United States was at the Rhode Island Hospital in 2000.5,6
In the simplest kidney exchange, between 2 incompatible patient-donor pairs, the patient in each pair receives a compatible kidney from the donor in the other pair. Kidney exchange today involves many other kinds of exchanges: among 3 or more pairs; and including compatible pairs who may receive a better matched kidney; and with chains begun by non-directed donors. This reflects considerable progress in the last decade.
The initial proposal for multihospital exchanges proposed integrating exchange among compatible and incompatible pairs together with chains of transplants initiated by nondirected donors.1 However, for logistical simplicity, the initial organization of the New England Program for Kidney Exchange under Frank Delmonico’s direction involved only simple exchanges between two pairs7‐9; and related practices were initially adopted elsewhere also.10‐12
The New England Program for Kidney Exchange and others soon developed the capability to regularly do exchanges among three pairs, and to organize short chains initiated by a nondirected donor.13,14 However, the number of transplants that could be accomplished in a single exchange or chain was limited by the logistics arising from the fact that all surgeries were conducted simultaneously to ensure that no patient-donor pair donated a kidney but then failed to receive one.
A simple cost-benefit analysis suggested that, unlike an exchange entirely among patient-donor pairs, a chain begun by a nondirected donor might be conducted nonsimultaneously.14 Such a chain would begin with a donation by the nondirected donor, and no patient-donor pair would donate a kidney until after they had received one. If a link in the chain was unexpectedly broken when a planned donation did not occur, the pair that had been scheduled to receive that donation would still have a kidney to exchange, and so could participate in a future exchange (unlike in an exchange entirely between patient-donor pairs, in which a broken link would impose an unacceptable cost on a pair that had given up their kidney without receiving one). Because the costs of a broken link would be less, the benefits of a nonsimultaneous chain, in terms of the larger number of transplants it could facilitate, could be explored.
The first nonsimultaneous chain, organized by Michael Rees through the Alliance for Paired Donation, was begun in 2007.15 At the time, it was reported it had completed 10 transplants—there were 20 people in the chain, the last one being a donor who had not yet been matched with a recipient. Another 12 people were eventually added to the chain before it was ended with a donation to a patient on the deceased-donor waiting list, who did not have a paired donor to continue the chain.
Recently, the majority of kidney exchange transplants in the United States have been conducted through chains, including majority of the most highly sensitized patients.16 This is in part because, as transplant centers have learned to conduct kidney exchanges, they often transplant their easiest to match pairs internally, enrolling only the hardest-to-match pairs in one of the multihospital kidney exchanges, and thus these enrolled pairs contain an unusually high concentration of highly sensitized patients.17 The patient-donor pool thus consists of many hard-to-match pairs, which makes it unlikely that a pair that can donate a kidney to another pair can also receive a kidney from that pair. So nondirected donor chains are often the only way a hard-to-match pair can both receive a kidney and donate one.18,19
By 2013, kidney exchange transplants had grown to more than 10% of living donor transplants in the United States, through a variety of multihospital20,21 and single-center22,23 programs, and are increasing elsewhere.24,25 However, more could be done to increase access to transplants through exchange.
Extending the Reach of Kidney Exchange
One way to make kidney exchange accessible to more patients would be to simplify participation. Developing a standard acquisition charge for living donor kidneys26 would remove some barriers that arise, for example, from different costs of nephrectomies at hospitals that may need to ship each other kidneys. And matching algorithms could be adjusted to guarantee hospitals that they and their patients will not lose transplants or sacrifice patient care if they enroll all pairs in exchange (and not just hard-to-match pairs).17 Enrolling easy-to-match pairs, including compatible pairs, can be organized to help those pairs find better matches, and also makes it much easier to find matches for hard-to-match pairs.9,27,28 Incentives for transplant centers to enroll their nondirected donors are already being implemented (a chain typically is terminated with a patient on the waiting list of a center that enrolled a nondirected donor).
Another way to accomplish more transplants through exchange would be to allow some nondirected donor chains to be initiated with deceased donor kidneys1 which, properly organized, could facilitate more transplants and shorten the wait for deceased donor kidneys for all patients.
Kidney exchange in the developed world could also be extended to patient-donor pairs from countries in which treatment for ESRD is essentially unavailable for large parts of the population.29 Such patient-donor pairs could, for example, be invited to come to the United States to participate in kidney exchange,30 financed by the American taxpayer from the savings that result from removing an American from dialysis through receiving a transplant, which are more than sufficient to finance the additional surgeries.31 (The bureaucratic obstacles to such exchanges and financial arrangements will be formidable, but the potential to aid both domestic and foreign patients is substantial.)
How Else to Increase Donation?
There remain many avenues other than kidney exchange through which the shortage of transplantable organs might be reduced.
In the United States, the scope for recovering many more transplantable organs from deceased donors seems somewhat limited for most organs, given current technology and recovery rates. However, there is suggestive evidence that more frequent opportunities to register as a deceased donor would increase registration, and that the manner in which registration is solicited can influence rates of family consent for donation.32
There is growing consensus that donors should not face financial disincentives from donating,33,34 and recent evidence that the costs borne by living donors are substantial enough to reduce donation in recessions.35,36 There is consequently great interest in exploring ways to remove disincentives or provide inducements for donation.
Several novel features of recent Israeli legislation are worth study.37 Deceased donation is encouraged by giving registered donors and next-of-kin of deceased donors some priority to receive deceased donor organs. Living kidney donors are also reimbursed 40 days wages, at their own wage rate, to offset the costs of donation. Initial indications are that the new Israeli law is increasing donation.38
The most contentious part of the discussion of how to increase donation concerns cash compensation to donors, particularly living kidney donors. With the prominent exception of Iran, which specifically permits cash payments for kidneys,39 there does not appear to be a legal market for the purchase and sale of organs for transplant anywhere else, although illegal black markets are widely reported, and occasionally prosecuted.
However, the critical shortage of transplantable organs around the world prompts continual discussion of whether to relax the ban on cash compensation. For example, the March 2014 issue of the Journal of Medical Ethics devoted 5 articles to the subject, all by philosophers. Although this discussion is too important to be left only to philosophers, neither can it be confined to the ongoing debate among transplant professionals, given the public resources devoted to transplantation and the important implications transplantation has for health policy.
The arguments, pros and cons, will already be largely familiar to those who follow this debate. I will simply try to add some context to the discussion by noting that the ban on organ sales is not unique: other kinds of markets have also been banned in the past, and presently, and laws have changed over time.
Of course, banning markets does not always end them: black markets for narcotics make clear that outlawing markets is simpler than abolishing them. In the United States, the manufacture and sale of alcoholic beverages was illegal from 1920 to 1933, during which time black markets for alcohol thrived. Less familiarly, an 1824 editorial in The Lancet comments on the black market in which medical schools bought cadavers for dissection from grave robbers, known as “resurrection men,” because the only cadavers that could legally be dissected were from executed murderers.40 (The Anatomy Act of 1832 expanded the sources of legal cadavers for dissection in Britain.)
Let us call a transaction repugnant if some people want to engage in it, and others, who are not materially affected, do not think they should be allowed to.41
By this definition, sales of kidneys are widely repugnant, as are (or were) the sale of narcotics, alcohol, and cadavers. But note that the ban on kidney sales is different from these other bans, since there is, or was, general disapproval of narcotics, alcohol, and dissection. But there is no similar disapproval of kidney donation and transplantation; it is only sales that are repugnant.
This turns out not to be too unusual: a transaction that is not otherwise repugnant sometimes becomes so when money is added to the mix. For example, charging interest on loans was largely banned in medieval Europe, although loans were permitted. (The relaxation of that ban has had profound effects on the modern economy.) Note that repugnance doesn’t only change in one direction—some transactions that used not to be repugnant are widely banned today. Indentured servitude, for example, is no longer legal in the United States, although it was once a common way of purchasing passage across the Atlantic.41
Some transactions are banned in some places and not others, for example, those concerning sale of blood and blood products, and reproductive goods and services such as sperm, eggs, and surrogacy. Legal markets in some places and not others give rise to “fertility tourism,” and many countries that ban payment for blood plasma import plasma products from the United States, where such payments are legal.42
The repugnance to kidney sales involves concerns about the identity and welfare of potential sellers. The same concerns cause many proposals for allowing some forms of compensation to address the need to avoid exploiting the poor and vulnerable, as existing black markets for kidneys are widely seen to do. The debate on how to proceed seems likely to focus on removing disincentives to donate and providing incentives that are not seen as leading to coercive or exploitative situations. The debate can be furthered by identifying specific sources of repugnance and considering how inducements could be structured to avoid them.43‐45
In the meantime, kidney exchange has proved to be a way of bringing some of the benefits of exchange to transplantation without running into the barrier of repugnance. So it seems promising to consider ways of extending its reach, as discussed above.
To work well, markets need to attract many of the potential participants, they have to deal effectively with the congestion that can arise from having many participants, and they have be simple and safe to participate in.46 Successful markets also have to continually adapt to changes in the environment.47
For kidney exchange, those things mean that we need to learn from best practices, and develop new ones. We need to make it safe for transplant centers to enroll easy-to-match pairs, including compatible pairs; and to reduce financial barriers to participation by transplant centers. International kidney exchange, and the use of deceased donor kidneys to initiate some chains, could extend the reach of kidney exchange.
For transplantation, more generally, the shortage of organs relative to the demand is a pressing problem. Finding ways to remove disincentives to donation, and continuing the sometimes difficult discussions about providing incentives to ease the shortage of organs without leading to exploitation, could provide some relief.
The author received helpful comments from Drs. Frank Delmonico and Mike Rees, although they are not implicated in the views expressed here.
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