Where 360,000 Kidney Transplant Patients Disappear Before Evaluation

The conversation about kidney transplantation in America is almost always a conversation about waiting. How long the list is. How few donors there are. How long a patient must sit on dialysis before an organ becomes available. That framing is not wrong, but a large new study suggests it is incomplete — and that the shortage we talk about is shadowed by a different, less visible problem happening earlier in the process, before any waiting has begun.

A massive national study found that nearly half of Americans with kidney failure who are referred for a transplant never even begin the evaluation process, and only 19% make it onto the transplant waitlist. Researchers discovered that factors such as where a person lives, whether they are married, their income level, language, age, and even which transplant center they use can dramatically affect their chances of moving forward. The study, led by researchers at NYU Langone Health and published in the Journal of the American Society of Nephrology^[2], is the most comprehensive look yet at what happens — or fails to happen — between the moment a nephrologist sends a referral and the moment a patient actually joins the queue for a new organ.

The study addresses a knowledge gap by meticulously analyzing data that track patient progression through each sequential step: referral, evaluation, waitlisting, and transplantation. Leveraging the Epic Cosmos database, which aggregates over 300 million electronic health records from more than 1,850 medical institutions — including over a third of all U.S. transplant centers — the research team was able to follow 720,348 adult patients referred for kidney transplantation between 2014 and 2025. The numbers that come out the other end of that pipeline are stark: of the referred candidates, 48 percent initiated evaluation, 19 percent were waitlisted, and 10 percent ultimately underwent transplantation.

The Black Box Before the Waitlist

Medicine has a long habit of measuring things from the point at which they become legible to institutions. For organ transplantation, that point has traditionally been the waitlist. While experts have studied what happens once people make it onto the list, little attention has been paid to challenges in making the waitlist in the first place. Co-senior author Allan Massie, PhD, referred to the lack of national data on patient characteristics or outcomes prior to waitlisting as a "black box." For the first time, investigators had access to national data that could provide insight into the process of the four stages of kidney transplants: referral, evaluation, waitlist, and transplant.

This invisibility has structural roots. There is no mandate for transplant centers to report which patients have been referred to them for transplant evaluation, which candidates do not complete a transplant workup, or which patients are deemed unsuitable for waitlisting and the reasons for these denials. When the data aren't collected, the attrition doesn't exist — at least not officially. Patients fall out of consideration and the system, having never formally logged them, registers nothing amiss. The organ shortage looks like the only problem because the pre-shortage problem has no paperwork.

“"Which transplant center you go to, where you live, and even whether you are married all appear to influence your chances of moving forward to the waitlist for a new kidney."”

What the Evaluation Process Actually Demands

To understand why so many patients never start, it helps to understand what starting actually requires. After receiving a referral, patients must complete an extensive medical assessment designed to evaluate their overall health. This often includes blood tests, chest imaging, cancer screenings, and other examinations. The process may require multiple appointments over several months while patients continue attending regular dialysis treatments. Dialysis itself — typically three sessions a week, each several hours long — is not a minor backdrop. It is an exhausting, time-consuming anchor that makes every additional medical appointment a logistical problem.

The evaluation process, demanding repeated visits for comprehensive testing — including hematologic assays, radiologic imaging like chest X-rays, and oncologic screenings — can extend over months. This prolonged and intricate schedule poses significant strain on patients, particularly those simultaneously managing frequent dialysis treatments. For a patient without reliable transportation, without a spouse or family member who can accompany them, without an employer who allows flexible scheduling, and without fluency in English, each of those appointments is a negotiation with circumstances that have nothing to do with medical fitness.

Individuals who were never married, patients with severe obesity, and those residing in rural zip codes were associated with reduced rates of evaluation initiation. Furthermore, patients who were older, of reduced socioeconomic status, and those who spoke Spanish as their first language were especially unlikely to progress. Patients treated at small centers or at programs in the South were similarly unlikely to progress. Those patterns don't describe a random distribution of medical complexity. They describe a map of social disadvantage.

The Center You Go To Changes Your Odds

Institutional factors also shape patient outcomes. Smaller transplant centers, often with constrained resources and fewer transplant slots, tend to adopt more conservative patient selection criteria. This resource scarcity may lead to heightened risk aversion, amplifying the likelihood that individuals are filtered out early in the process. In other words, the same patient, presenting with the same clinical profile, may have meaningfully different odds of reaching the waitlist depending on which institution happens to receive their referral. That is not a feature of a well-designed system. It is a feature of a system that has never been required to account for what it loses before the clock starts running.

This concern is not new, but it has been hard to quantify at scale. Prior work in the American Journal of Transplantation found that kidney transplant programs across the U.S. vary considerably^[3] in their pre-transplant practices — how they screen referrals, what BMI thresholds they apply, how aggressively they pursue candidates. Kidney transplant programs in the United States are known to have substantial variations in pre-transplantation practices and policies that may reflect the lack of consensus surrounding many aspects of transplant care. The new NYU Langone study, by tracking patients through all four stages nationally, now shows us the downstream human cost of that variation.

Provider perception adds another layer. A systematic review of non-medical barriers to early transplant access^[4] found something that should give the field pause: in a survey of over 500 dialysis facility staff, only 23% of staff perceived that more than 50% of their patients were eligible for a kidney transplant, despite previous research showing that less than 15% of patients have absolute medical contraindications to transplant. If the people running dialysis facilities believe, incorrectly, that the majority of their patients are ineligible, the referrals that get written — and the energy put behind them — will reflect that belief. Clinician perception becomes its own filter, applied before any formal evaluation takes place.

“The organ shortage looks like the only problem because the pre-shortage problem has no paperwork.”

Disparities That Don't Disappear With Better Health

One of the more unsettling strands in the research literature here involves patients who have no obvious medical reason to be excluded. A study published in JAMA Internal Medicine examined kidney transplant waitlisting among young patients without medical comorbidities^[1] and found that waitlist disparities extend to younger patients with no medical contraindications to kidney transplantation. In a retrospective study of 52,902 U.S. patients aged 40 years or younger with no major medical comorbidities, only 30% were waitlisted for a kidney transplant within one year of dialysis initiation, and 51% within five years. The remaining 49% of younger, healthier patients still were not waitlisted by five years on dialysis.

These results add further credibility to the interpretation that structural barriers, not simply patient-level barriers, play a critical role in perpetuating inequities in access to this life-saving treatment. Clinical interventions alone are insufficient to mitigate the resulting disparate cost, survival, and quality-of-life outcomes that disproportionately impact already disadvantaged communities. The data also reveal a particular pattern in how race intersects with each specific step. Black, non-Hispanic patients had a higher rate of referral — but lower evaluation start among those referred — compared to white non-Hispanic patients. Getting the referral written, in other words, does not mean the referral goes anywhere.

What Closing the Gap Would Require

"When we're finding that less than half of patients are even evaluated, then nephrologists need to recognize that that referral isn't the end of the line," Massie said. "They can follow up with patients, they can see if patients are having practical barriers, if they're unable to get in contact with the transplant center, if they have logistical barriers to making an appointment happen." That sounds straightforward, but it asks nephrologists to take on coordination and navigation work that the system has not built infrastructure to support. Referrals, historically, have been hand-offs. This evidence suggests they need to function more like active commitments.

Interventions such as the use of telemedicine, rideshare reimbursements by transplant centers, and local or federal policies that provide reimbursement to patients for missed work could help address these barriers. The Cleveland Clinic has also pointed to a problem of timing: "Most patients are referred for transplant evaluation late in the course of their disease," notes the medical director of one kidney transplant program. "We receive over 1,500 kidney transplant referrals each year, and about 60% of patients we evaluate are already on dialysis." Earlier referral — before dialysis dependence — would give patients more time and more physical reserve to complete the evaluation gauntlet.

The broader accountability gap remains: without mandatory national reporting on what happens between referral and evaluation, individual institutions face no systematic pressure to examine their own attrition rates. Transplant centers already collect referral data for all organs, and infrastructure to submit these data is already in place with UNOS. National policies should be amended to require the collection of these data from centers. Until that happens, the funnel stays dark above the waitlist, and the scope of the problem stays formally invisible.

Kidney transplantation is not simply the best treatment for end-stage kidney disease — it is, by a substantial margin, associated with longer survival and better quality of life than long-term dialysis. The question the NYU Langone study forces into the open is not whether organs are scarce. They are. The question is how many of the people who need a transplant are being silently eliminated by a process that has never been required to count them. Half, the data now suggest. Half, before the clock even starts.

References

1. Disparities in Kidney Transplant Waitlisting Among Young Patients Without Medical Comorbidities (doi.org)
   Retrospective study of 52,902 patients aged 40 or younger with no major comorbidities found only 30% waitlisted within one year and 51% within five years of dialysis initiation.
2. Evaluating Barriers to Kidney Transplantation in... : Journal of the American Society of Nephrology (doi.org)
   Published the NYU Langone study tracking 720,348 kidney transplant referrals through all four stages from 2014–2025, finding 48% initiated evaluation and only 19% were waitlisted.
3. Kidney transplant candidacy evaluation and waitlisting practices in the United States and their association with access to transplantation (pmc.ncbi.nlm.nih.gov)
   Documents substantial variations in pre-transplant screening practices, BMI thresholds, and candidate pursuit strategies across U.S. kidney transplant programs.
4. Non-medical barriers in access to early steps of kidney transplantation in the United States - A scoping review (pmc.ncbi.nlm.nih.gov)
   Survey of 500+ dialysis facility staff showing only 23% perceived over half their patients eligible for transplant, despite research showing less than 15% have absolute medical contraindications.