The proposal for the allocation of kidneys for transplant that is currently being considered by the Kidney Transplantation Committee of the United Network for Organ Sharing is a bit of a compromise. The system would give the highest-quality kidneys to the 20% of recipients with the longest estimated posttransplant survival time. The other 80% of kidneys would be matched roughly by age, with recipients aged 15 years older or younger than the age of the deceased donor getting the highest priority.
In my opinion, it is a much better proposal than was the LYFT (Life Years From Transplant), but it still distributes the transplant procedures away from the older patient to the younger patient.
By Dr. Mitchell Henry
When we do modeling, we look at whether or not we are affecting the total number of kidneys or the total number of opportunities to be transplanted. This allocation proposal actually decreases the total number of kidneys by a small amount (about 50 kidneys), so it doesn’t affect the number of kidneys that are transplanted overall, but it doesn’t increase the numbers, either.
The current proposal involves the "kidneys that look like me" approach. That means that if I’m 30 years old, I’m more likely to get a young kidney, and if I’m 60 years old, I’m much more likely to get an older kidney. That in itself is not bad. But what this plan does is distribute the transplant opportunities disproportionately to younger patients. In the 50- to 64-year-old age group, there are 6% fewer kidneys likely to be transplanted, and in the 65 years and older group, 5% fewer. That translates to 7% more kidneys in the 18- to 34-year-old age group, and to 4% in the 35- to 49-year-old age group. Overall, there is an 11% shift from older to younger.
The problem is that the vast majority of our potential recipients are older patients. We are able to keep people alive longer, especially those with comorbid diseases. As the numbers of these patients increase, the opportunities for them to be transplanted decrease. One unintended outcome of this allocation system is that if we are going to transplant older kidneys into older recipients, we might promote worse outcomes if the older kidney doesn’t work well early on. For example, if I have a 65-year-old patient with diabetes, hypertension, and heart problems, and I put a 66-year-old donor kidney into that patient, the last thing I want to have happen is for that patient to go on dialysis for a week or two while we wait for that older donor kidney to heal and start working. By contrast, a 45- or 50-year-old patient might be better able to tolerate that older kidney.
On the other hand, this allocation program may promote more focus on which older patients might have opportunities for a living-donor transplant. We could identify people who are less likely to do well waiting on the transplant list and emphasize the opportunity for them to get a living-donor kidney. Data show that elderly patients with comorbid conditions do quite well with a living-donor transplant, and it makes little difference whether the donor is related or unrelated to the patient.
What I would like to see modeled is how this allocation impacts the waiting time on the transplant list. If fewer older patients are being transplanted and more older patients are joining the list, the only conclusion I can draw is that the waiting time for the older patient would be longer. However, older patients do worse on dialysis than do younger patients. Are the increased waiting times in the older patients going to translate into increased deaths on the waiting list, or will transplant centers be more discouraged about placing older patients on the list, and thus will we see a downturn in the number of patients who are put on the list?
One issue that remains to be resolved is the disparate notion that the UNOS and the Centers for Medicare and Medicaid Services continue to urge organ-procurement organizations to proceed with all possible donors, yet transplant centers are being penalized by these same regulatory bodies for outcomes that are consistent with transplanting nonstandard donor organs into higher-risk recipients. No doubt there can be benefits to those recipients by transplanting these patients and getting them off dialysis, but programs are going to be hesitant to put their existence into question with the expected poorer outcomes with this donor-recipient combination. This needs to be addressed in order to optimize the number of patients transplanted and decrease organ discards for fear of donor quality, which will be especially important in a new kidney-allocation scheme.