What can we learn from discarded deceased donor kidneys?

The inadequate supply of deceased donor organs is a universal transplantation mantra. Solutions to this plaint are few and most are untenable in the case of kidney transplantation. Restricting the number of transplant candidates can be dismissed as incompatible with our general philosophy of offering all who may benefit from transplantation a chance to hit a home run off a throw from the pitcher we call the allocation system. By squeezing on the increasingly hard stone of society’s decedents, more deceased organ donors have been realized, mainly by procuring incremental kidneys from the ranks of older individuals and those with infirmities once deemed taboo. In the United States, the Organ Donation Breakthrough Collaborative has been successfully embraced by the transplant community as a means to promote this end. The number of procured kidneys is increasing. But to date we have not achieved as much success with the end product (actual transplants) as we have had on the supply side (procurement). The source of this discrepancy is the large number of deceased donor kidneys that are procured in good faith, but ultimately discarded. They are like kids who show up for a pickup ball game and, worse than being the last chosen for a team, are not chosen at all. In the United States alone, we are leaving 1,500 kids on the sidelines each year. Our European colleagues have teamed up kidneys from older donors with candidates who are older. They do it explicitly, through the Eurotransplant Seniors Program (ESP). The discard rate in the Eurotransplant region is only onethird that of the United States, despite the fact that a higher proportion of the procured kidneys are from donors over age 50 (40% vs. 27%). Are these interesting facts causally related? The authors of the article in this issue by Cecka et al. (1) have conducted a thoughtful comparative analysis of data from two large transplant registries to examine this question and would have us believe so. They posit that an allocation policy like the ESP that directs older donor kidneys to older candidates would reduce the discard rate in the United States. Let us examine this hypothesis in more detail. A comparison of the characteristics of older donor kidneys in the United States and Europe was not made by Cecka and colleagues. So, if older American kidneys are from decedents with significantly more comorbidities than their European counterparts, then the predicted benefit accruing to and acceptance by potential transplant candidates may be insufficient to persuade increased utilization. The authors acknowledge this point. The specific reasons for discard are critical to our understanding of the process of discard. Much has been made of the results of biopsy of donor kidneys in determining suitability for transplantation. As the authors point out, current practice in the United States is often traced to a small study by Gaber et al. (2), which reported on outcomes from only eight kidneys with more than 20% glomerulosclerosis. Data from the Scientific Registry of Transplant Recipients suggests that even without considering biopsy results, the performance of the biopsy per se, other things being equal, is associated with a significantly higher risk of discard (unpublished data). Perhaps we need to focus more research attention on the psychological impact of knowing that a biopsy was done. Cecka et al. showed that nearly one-half of the kidneys discarded from donors over age 50 in the United States listed the biopsy result as the predominant reason for discard. Because of the widespread practice of biopsy of kidneys from expanded criteria donor (ECD) kidneys, appropriately blinded prospective studies of the utility and predictive value of biopsy are very difficult to conduct. Finally, returning to the issue of appropriate pairing of donor and recipient, the authors suggest, but show no data, that so-called age matching would reduce discards in the United States. As mentioned above, the ESP program incorporates explicit age-matching for older donors. In the United States, implicit age-matching is already widely practiced (3), and recently published data suggest that reserving older ECD kidneys for older transplant candidates is consistent with the goal of maximizing transplant survival benefit (4). In the end, some of the strategies to achieve the goals related to utilization of donor organs and those pertaining to maximization of benefit may converge. Whether these are pursued explicitly, as in the ESP program in Europe, or implicitly, as has been done in the United States through changes in practice patterns guided by experience and careful analysis, is less important than working toward improving access to renal transplantation by maintaining our focus on the mantra.