‘Increasing Kidney Demand’ Would Require Increase in Supply

With efforts underway to expand access to the kidney transplant waiting list to more patients, including many with end-stage kidney disease (ESKD), new research underscored the corresponding significant increase in the number of donor organs needed to prevent increased waiting periods for patients.

“We found that expanding the transplant waiting list would result in longer wait times that can only be alleviated by drastically increasing organ supply,” the authors report in the study published this week in JAMA Network Open.

Noting that “the transplant community is certainly aware that increasing demand without increasing supply would lead to longer wait times, [our] estimates of how much wait times could lengthen if the waiting list expands without meaningfully addressing the organ shortage might be a wake-up call for some,” lead author Jillian S. Caldwell, DO, of the Stanford University School of Medicine, Division of Nephrology, in Palo Alto, California, told Medscape Medical News.

As many as 90,000 people were on the waitlist for a kidney transplant in the United States in 2023, yet only about 28,000 kidney transplants were performed during the period. Research showed that fewer than 50% of patients who were wait-listed 10 years ago have gone on to receive a transplant since then.

Meanwhile, with kidney transplant waiting lists typically restricted to healthier patients who have a greater chance of survival, the prospects of receiving a kidney are worse for patients with ESKD, with only about 1 in 8 making it onto the waiting list. Additionally, well-documented geographic, racial, ethnic, and socioeconomic disparities further restrict access to a kidney transplant for many.

Public policy initiatives to tackle the issue by increasing access to the waiting list include the CMS’ Increasing Organ Transplant Access (IOTA) Model, designed to improve access to kidney transplantation and maximize deceased donor kidneys.

To address the key question of how many additional organs would be needed to meet demand if the waiting list is expanded, Caldwell and colleagues used an analytic model with a simulated cohort involving 662,190 transplant-eligible patients, drawing from various analyses of US transplant data.

In the cohort, the mean age was 58.7 years, 49% were women, 41% were Black individuals, 25% were Hispanic individuals, 35% were non-Hispanic White individuals, and 12% were Asian individuals.

Under the model, the median wait time for patients on the list in the model as status quo, considering transplantation, waiting list additions, removals, and deaths, was 32.8 months.

The results showed an addition of 10% more patients to the waiting list would result in an estimated median increase in the time on the waiting list by 4 months to 36.8 months.

A 50% increase in the number of patients on the waiting list was estimated to lengthen wait times by 20 months over baseline, to 52.6 months.

An additional 2800 kidneys would be necessary to maintain or shorten wait times related to a 10% expansion of the waitlist, while 11,000 additional organs would be necessary to maintain or shorten wait times if the waitlist grew by 50%.

In looking at the estimations based on the transplant type, for deceased donor transplants, a 10% waiting list expansion would not be sufficiently offset by a 10% increase in deceased donor organs, with the median wait time still increasing by 2 months, to 34.5 months.

Furthermore, even a 50% increase in the number of patients on dialysis placed on the waiting list would make only a small dent in terms of improving waiting list acceptance rates for patients on dialysis, Caldwell noted.

“Currently, only 12% of patients receiving dialysis in the US are on the kidney transplant waiting list,” she said. “A 50% relative expansion would increase that number to 18%, which still represents only a fraction of patients receiving dialysis.”

Improving Utilization of Deceased Donor Kidneys

A key focus in increasing the supply of kidneys for transplant is on improving the rates of kidneys that are utilized. Recent research showed that as of 2022, more than a quarter (26.7%) of kidneys recovered from deceased donors wound up not being transplanted, mostly due to the donors being older or sicker.

According to one study comparing utilization rates in the United States to France, up to 60% of kidneys discarded in the United States would have been transplanted in the French system.

However, based on the high increases in supply needed to offset increases in the waiting list, the authors underscored that “reducing the discard rate alone is unlikely to meet the demands of waiting list expansion, and strategies must focus on increasing deceased donor organ procurement.”

Specifically, optimizing donation after circulatory death (DCD) procurement would likely be the most effective strategy to increase the deceased donor organ supply, Caldwell said.

“On average, organ procurement organizations obtain about 30% of their deceased donor kidneys from DCD donors, with some centers procuring as few as 20% and others up to 53% from DCD donors,” she said. “We estimate that the total deceased donor organ supply could be doubled if all centers procured approximately 50% of their organs through DCD donors.”

In kidneys from living donors, rates have generally “been stagnant over the past decade,” the authors noted, with factors such as comorbidities, immunologic incompatibility, and financial limitations often preventing those transplants. Furthermore, racial disparities in living donor transplantation have only increased over time.

Measures designed to address that problem include the End Kidney Deaths Act, which proposes refundable tax credits of $10,000 per year for 5 years to living kidney donors to offset the economic burden of donation.

“Given these findings, there is a critical need to continue research and policy initiatives that promote living donation, particularly for patients of designated racial and ethnic minority groups and lower socioeconomic status,” the authors asserted.

More broadly, “efforts to expand access to transplantation must consider the need for growth at all stages of the transplant process and should incorporate estimates of changes in median wait times to inform all affected stakeholders,” they said.

Addressing Supply and Demand Interplay Is ‘Crucial’

Commenting on the study in an editorial, David C. Cron, MD, of the Department of Surgery, Massachusetts General Hospital, in Boston, and colleagues said the results underscored the need for a multifaceted approach to address the complex challenges in improving waiting list outcomes.

“If efforts to expand waiting list access succeed, wait times will likely increase in the absence of a compensatory increase in organ supply,” they wrote. “The organ shortage, however, must not serve as an argument against expanding waiting list access.”

“Instead, expanding access and increasing organ supply must proceed in tandem to meet the needs of all patients,” they added.

They agreed that improving the deceased donor supply “may be a more attainable strategy” in meeting demand, considering the ongoing challenges with living donors.

“Living donation seems like the logical place to invest effort since theoretically the ceiling for number of potential living donors is much higher that what we currently are doing,” Cron told Medscape Medical News.

“But it’s a reality check to see we’d need to triple the number of living donor kidney transplants to compensate for a 50% increase in waitlist expansion. I think this tells us we will need to focus efforts on both living and deceased donation simultaneously to meet the demands of a growing waitlist population.”

In terms of improved use of deceased donor organs, Cron noted that “many centers are more aggressive in using these organs, understanding that a one-size-fits-all approach won’t help us achieve our goals, but rather it’s about matching the right organ for the right recipient and considering the survival benefit of transplant,” he said.

“For example, it is often better to take a less-than-ideal kidney sooner rather than waiting years longer on dialysis until a hopefully more ideal organ comes along.”

Overall, “as a field, we have become better at understanding risk and more willing to use DCD kidneys and kidneys from older donors or donors with moderate acute kidney injury,” he said.

The study received funding from the American Kidney Fund Clinical Scientist in Nephrology Award and the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health. Caldwell and Cron had no disclosures to report.