We found no evidence that any of the 3 main concerns with a regulated system of payments for living kidney donation would manifest if such a market were established. Providing payments did not dull persons’ sensitivity to the risks associated with donor nephrectomy, suggesting that payment does not represent an undue inducement— one that would make rational choice difficult. Furthermore, providing payments did not preferentially motivate poorer persons to sell a kidney, suggesting that payment does not represent an unjust inducement— one that would put substantially more pressure on poorer persons than on wealthier persons.
Similar to real-world observations from Iran’s partially regulated kidney market (39
), we found that poorer persons were more likely than wealthier persons to consider donation to an unrelated donor. However, contrary to both our hypotheses and concerns expressed about the Iranian market (40
), we found that poorer persons were more willing to donate independent of payment (). Even after restricting our analyses to the poorest and wealthiest participants, we found no evidence that payment influenced these 2 groups differently. This result is consistent with previous observations that payment does not preferentially motivate clinical research participation among poor persons (25
). Thus, our results do not corroborate concerns about the ethics of payment per se, but rather they suggest that poorer persons may contribute disproportionately to the supply of organs with or without payment. Reasons for these behaviors, perhaps including differences in the opportunity costs of donating among richer and poorer patients, merit future study.
We also found no evidence that introducing monetary incentives would “crowd out” a person’s altruistic incentives to donate. This result is consistent with a previous public survey that found that payments would encourage kidney donation for monetary reasons far more commonly than it would discourage donation for altruistic reasons (41
). Together, these studies cast substantial doubt on the concern that offering payments would undermine altruistic donation. They suggest that systems allowing payment for kidney donors would produce more transplantable organs than systems barring it.
Our study has several strengths. First, by experimentally manipulating the presentation of factors associated with donation decisions within participants, we forced persons to reveal their preferences and presumed behaviors (26
). This approach contrasts with questionnaires that merely query stated preferences. Second, our study had substantial power to detect even minimal statistical interactions between payment and income and between payment and risk, as reflected by the narrowness of the CIs (42
) surrounding the point estimates of these interactions (). Thus, it is unlikely that we did not detect a true effect of payment as either an undue or an unjust inducement. Third, the high response rates to the survey and component items reduce the possibilities of important nonresponse biases. Fourth, the validity of the results is suggested by the low proportion of internally inconsistent responses (24
An important limitation of our study is that participants’ responses to hypothetical offers may not reflect the decisions they would make if they were truly offered payment for a kidney. For example, hypothetical offers of payment may be insufficient to blunt a person’s perception of risk, but real money might do just that. However, it seems unlikely that our study failed to detect real effects of money because participants clearly paid attention to and were influenced by money. We found that larger payments encouraged donation in general, and, as expected, payments were particularly important when participants contemplated donating to strangers. Furthermore, the experimental presentation of structured vignettes has been shown to produce valid results in other settings (43
). Nonetheless, evaluating responses to hypothetical situations can take us only so far; ultimately, the effects of payment will need to be tested in natural settings.
Another possible limitation of the study regards the diversity of participants. Our sample contained a greater percentage of highly educated persons than expected from the general public. However, we found no relation between education and any outcome measure, and none of our results changed when analyses were restricted to the least-educated members of the sample. Similarly, it is possible that we did not enroll persons at the very extremes of the U.S. income distribution. However, our sample included roughly equal proportions of participants in each of the 6 predetermined income brackets, and we found unchanged results when we limited analyses to the highest versus lowest brackets.
Finally, some might believe our study is limited in that we did not address the views that payment for kidney donation is intrinsically unethical because it represents “commodification” of the body or that introducing payments for organs could have broader social ramifications, such as curtailing a person’s general selflessness. However, these arguments apply equally to payments for surrogate motherhood or clinical research participation—activities that carry similar if not greater risks than kidney donation (11
) yet are legal in most nations. Thus, regardless of the merits of these arguments, regulated kidney sales are difficult to challenge on these grounds.
Our study adds evidence to what has been a largely theoretical debate about the propriety of paying persons to become living kidney donors. The results both corroborate predictions that payments could effectively increase the supply of transplantable kidneys (8
) and cast doubt on intuitions that payments would be undue or unjust, or would undermine a person’s otherwise altruistic behaviors (10
). Because participants’ responses to our questionnaires did not carry real-world consequences, our results are insufficient to support the establishment of a national system of regulated payments for kidney donation. Instead, because these and other empirical results counter theoretical concerns about regulated payments, we recommend proceeding with a highly controlled and geographically limited test of such payments that is explicitly designed to detect both intended and unintended consequences of real-world payments for living kidney donation.
Persons who need kidney transplants outnumber available kidneys. Payment to donors could encourage kidney donation, but it might create unethical inducements. People might not fully consider the risk of donation, or disadvantaged persons might feel pressure to donate. Payment might deter donations for altruistic reasons.
Researchers surveyed persons riding Philadelphia-area public transportation about whether they would donate a kidney under a range of scenarios that did and did not include various payments. Responses suggested that payment would not create undue or unjust incentives for donation or alter a person’s willingness to donate just to help another person.
Responses may not reflect what people would actually do if confronted with an opportunity for kidney donation.