The bottleneck nobody was tracking

Most research on kidney transplants focuses on what happens after a patient makes the waitlist — how long they wait, who gets matched with a donor, how outcomes vary once someone finally gets a new organ. A study out of NYU Langone Health, published June 20 in the Journal of the American Society of Nephrology and presented the same day at the American Transplant Congress in Boston, looked at the stage before that: what actually happens between a patient getting referred for a transplant and that patient reaching the list at all. The answer, drawn from the largest analysis of its kind to date, is that most people never make it that far.

The research team, led by Dr. Conor Donnelly, a resident and PhD student in NYU Grossman School of Medicine's Department of Surgery, analyzed a national dataset of 720,348 patients referred for kidney transplantation. The numbers are stark: only 19% of referred patients completed the full evaluation process required to join the transplant waitlist. Nearly 48% never even started that evaluation. Put plainly, for every five people whose doctor refers them for a kidney transplant, roughly one actually reaches the point of being listed as a candidate.

What the evaluation process actually demands

Getting referred for a transplant isn't the same as being cleared for one. Once a referral happens, patients undergo an extensive battery of medical tests, according to the study's methodology described by EurekAlert — bloodwork, imaging, cardiac clearance, psychosocial evaluation, and coordination with a transplant center's surgical and nephrology teams. That process can stretch over months, and it requires patients to show up repeatedly for appointments, often at centers that may be geographically distant from where they live and receive routine dialysis care.

Dr. Donnelly attributed much of the drop-off to the sheer complexity of navigating that system. "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," he said. That's a notable framing — it suggests the barrier isn't primarily medical ineligibility, but logistical and social friction embedded in how the evaluation process is structured and who has the support to get through it.

Who gets filtered out, and why that pattern matters

The disparities the study uncovered aren't randomly distributed. Patients who were unmarried, severely obese, or living in rural areas were significantly less likely to start or complete evaluation. Older patients, Spanish-speaking patients, and those with lower incomes faced even steeper odds of falling out of the process. Geography compounded the problem further: people treated at smaller transplant centers, or at programs located in the American South, were also less likely to progress toward the waitlist.

Being unmarried showing up as a meaningful risk factor is worth sitting with. It points toward something the medical literature has documented in other chronic disease contexts but rarely quantifies this precisely for transplant access specifically: having a spouse or partner to help coordinate appointments, manage transportation, and provide logistical support during a demanding multi-month evaluation appears to materially affect whether someone completes it. That's not a biological barrier to transplant eligibility. It's a structural one, and it's fixable in ways that a person's underlying kidney disease is not.

A gap in the research nobody had filled until now

Study co-senior author Dr. Michal A. Mankowski, an assistant professor in NYU Grossman School of Medicine's Department of Surgery, framed the significance of the finding directly: the results highlight the need to better support patients in progressing from referral to the waitlist, since many people who are possibly eligible for a transplant are not ultimately being listed. That distinction — possibly eligible, but never actually evaluated to confirm it — is the crux of what this study reveals. It's not that the transplant system is rejecting large numbers of unqualified applicants. It's that large numbers of potentially qualified patients are dropping out of a process before anyone can determine whether they qualify at all.

Mankowski said the research team next plans to extend this same analytical approach to other organ transplant types, where the referral-to-waitlist pathway may look structurally different but could reveal similar attrition patterns. That's a meaningful next step, because kidney transplantation has the largest referral population of any solid organ by a wide margin, and if similar bottlenecks exist for liver, heart, or lung transplant candidates, the scale of the problem across U.S. transplant medicine broadly could be considerably larger than this study alone captures.

What fixing this would actually require

The study doesn't prescribe a single policy fix, and the researchers were careful not to oversimplify what's clearly a multifactorial problem. But the pattern they documented — smaller centers and Southern programs showing worse progression rates, alongside socioeconomic and language-based disparities — points toward solutions that are more logistical than medical: expanding patient navigation support, particularly for non-English speakers and unmarried patients without built-in caregiver support; ensuring smaller transplant centers have adequate staffing and resources to shepherd patients through evaluation; and potentially standardizing evaluation protocols so patients aren't at the mercy of how efficiently their particular center happens to be run.

None of that requires a medical breakthrough. It requires treating the referral-to-waitlist pipeline itself as a healthcare access problem worth fixing with the same rigor typically reserved for post-transplant outcomes — because right now, for the majority of people referred, the system is failing them long before a donor organ ever enters the picture.

*This article was researched using publicly available reporting from NYU Langone Health, EurekAlert, ScienceDaily, Medical Xpress, and the peer-reviewed study published in the Journal of the American Society of Nephrology. It is intended for informational purposes and is not medical advice.*