Faculty Bibliography

KEY POINTS/CONCLUSIONS:In this cohort study of 720,348 adults referred for kidney transplantation from 2014 to 2025, only 48% were evaluated and 19% were waitlisted. Progression from referral to evaluation, waitlisting and kidney transplantation was limited by individual, center-level, and geographic factors. Some centers evaluated and waitlisted patients at rates far below the national average, and low-volume centers had lower rates of transplantation. BACKGROUND:Kidney transplantation is a cost-effective, lifesaving treatment of kidney failure, compared with dialysis. Unfortunately, most patients with kidney failure never undergo transplantation. METHODS:Using Epic Cosmos electronic health record data on all patients referred for kidney transplantation from 2014 to 2025, we assessed the stage-specific progression and attrition in the process of evaluation, waitlisting, and kidney transplantation. Center-level and individual (socioeconomic, geographic, and insurance status) factors associated with access to evaluation, waitlisting, and kidney transplantation were characterized using modified Poisson regression. RESULTS:Among 720,348 referred candidates, the median age was 55 years (interquartile range [IQR], 42-64); 47% of patients were White, 52% were male, and 87% were English speaking. Eighty-five percent of patients lived in urban areas. Of the referred candidates, 48% initiated evaluation, 19% were waitlisted, and 10% ultimately underwent transplantation. Among the referred patients who initiated evaluation, the median (IQR) time to evaluation initiation was two (1-4) months after referral; among the patients who were waitlisted, the median (IQR) time to waitlisting was four (2-9) months after evaluation initiation. Patients who were never married (0.94; 95% confidence interval [CI], 0.93 to 0.94), had severe obesity (0.70; 95% CI, 0.69 to 0.72), or were from rural zip codes (relative risk, 0.98; 95% CI, 0.97 to 1.00) were less likely to initiate evaluation. Low-volume centers had lower relative rates of transplantation (0.92; 95% CI, 0.88 to 0.96). In centers with documentation for nonprogression to evaluation, reasons for removal included not meeting criteria/not a candidate (18%), patient decision (13%), unable to contact (12%), death (4%), and financial/insurance complications (7%). CONCLUSIONS:Our study shows substantial attrition before kidney transplant waitlisting.

Pediatric deceased donor kidneys with acute kidney injury (ped-AKI) are at increased risk for non-utilization. To evaluate the post-transplant outcomes of ped-AKI recipients, we conducted a retrospective cohort study, comparing 17,731 adult recipients of kidneys from pediatric donors without AKI (ped-non-AKI, terminal serum creatinine (SCr)<1 mg/dL) to 1,589 ped-AKI recipients (SCr≥2 mg/dL). We used weighted logistic regression to estimate the association between ped-AKI and delayed graft function (DGF), and weighted Cox regression to estimate the association between ped-AKI and primary non-function (PNF) and all-cause graft failure (ACGF). Ped-AKI kidney recipients were at 6.0-fold (aOR=_5.325.98_6.72), 1.9-fold (aHR=_1.361.87_2.58), and 1.4-fold (aHR=_1.161.43_1.76) higher risk of DGF, PNF, and 1-year ACGF compared to ped-non-AKI recipients. En bloc ped-AKI recipients were at 5.6-fold (aOR=_3.295.57_9.43), 3.3-fold (aHR=_1.723.25_6.15), and 2.9-fold (aHR=_1.702.92_5.01) higher risk of DGF, PNF, 1-year ACGF compared to en bloc ped-non-AKI recipients. Among recipients of single kidneys from donors<20kg, ped-AKI recipients were at 8.9-fold (aOR=_4.348.87_18.12), 5-fold (aHR=_1.694.99_14.75), and 3.4-fold (aHR=_1.473.44_8.05) higher risk of DGF, PNF, 1-year ACGF compared to ped-non-AKI recipients. Ped-AKI kidney recipients have higher risks of early graft complications and failure. Risks are greatest for recipients of single kidneys from donors<20kg. Careful recipient selection and counseling are prudent when considering ped-AKI kidney offers.

Normothermic machine perfusion (NMP) may increase utilization of non-ideal donor kidneys through improved preservation and assessment. We assessed the use of a centralized perfusion service to rescue declined kidneys for transplant. Kidneys that exhausted standard OPTN allocation underwent 2 hours of NMP for additional assessment. The primary outcome was rescue for transplantation. Outcomes of NMP kidneys were compared to non-NMP kidneys transplanted during the study period at the same transplant centers. NMP was performed on 104 declined kidneys, and 94 (90%) were rescued for transplant. NMP donors were older, with a higher kidney donor profile index (KDPI) compared to non-NMP donors. Cold ischemia time was significantly longer in the NMP cohort (median 37.6 vs. 22.1 hours, p<0.001). The weighted percentage of delayed graft function (DGF) was 26.3% in the NMP group vs 60.2% in the non-NMP group (p=0.023). Overall graft survival was similar between the groups. With the use of a centralized NMP service, kidneys declined based on standard clinical parameters may be evaluated, rescued, and successfully transplanted. Kidneys undergoing NMP experienced significantly lower rates of DGF compared to non-NMP kidneys. Additional follow up is needed to determine the effects of NMP on long-term graft function.

We sought to understand the potential impacts of a rapidly evolving donor pool on the annual recalibration of the kidney donor profile index (KDPI). Using OPTN data, we examined the kidney donor risk index (KDRI) among deceased kidney donors recovered 2011-2024. We mimicked the OPTN's annual re-mapping process to measure the KDRI-to-KDPI calibration drift and used Cox regression to translate this drift into all-cause graft failure rate differences. The 50th/75th/95th KDRI percentile among recovered donors rose from 1.19/1.47/2.0 in 2011 to 1.40/1.77/2.36 in 2024. For donors with the same KDRI, the KDPI assigned in 2024 was as much as 13 points lower than the KDPI assigned in 2012. Holding other factors constant, the KDRI-KDPI calibration shift equated to 7 years of increased age (65 vs. 58) for KDPI 86% donors. Five-year graft failure risk was 9% higher (RR: _1.0871.093_1.097) for a kidney assigned a KDPI of 86% in 2024 versus 2012. Organ recovery practices have changed. The relationship between KDPI and organ quality has become a moving target, complicating shared decision-making and altering the meaning of allocation policy thresholds. Alternative solutions to annually remapping KDPI, such as establishing a fixed reference cohort or migrating away from KDPI, could be considered.

UNLABELLED:(N = 24 patients) among functioning grafts. DSA rebounded with levels progressively decreasing over time and no increase in DSA seen between 3 and 5 years. No AMR occurred between 3 and 5 years. Furthermore, no additional safety signals assessed as related to imlifidase were reported in this cohort. At 5 years, highly-HLA sensitized patients who underwent imlifidase desensitization prior to transplantation demonstrated excellent patient and graft survival, despite their high-risk immunological profile. Imlifidase offers a viable and effective treatment option for highly sensitized patients to achieve life-saving transplantation and continued optimism is warranted. CLINICAL TRIAL/UNASSIGNED:ClinicalTrials.gov (NCT02790437), EudraCT Number: 2016-002064-13.

Procurement biopsies are routinely obtained in the United States to evaluate kidneys considered for transplantation, but some argue that they may contribute to kidney nonutilization. Historically, biopsy decisions have been left solely to the discretion of organ procurement organizations (OPOs) and transplant centers. In September 2022, an organ procurement and transplantation network (OPTN) policy designating donors meeting specific clinical criteria as "biopsy-required" went into effect. Using OPTN data from 1 year before and after policy implementation, we used causal inference methods to estimate the policy's impacts on biopsy practices and kidney utilization. The overall biopsy rate remained stable at 62%, rising from 90.6% to 95.8% (P < .001) among biopsy-required kidneys while falling from 49.1% to 43.4% (P < .001) among biopsy-optional kidneys. After adjusting for changing donor characteristics, the policy was associated with a 5% decline in the biopsy rate (adjusted risk ratio = 0.95; P = .007). The overall kidney nonuse rate rose from 27.2% to 28.7%. After accounting for changes in donor characteristics, the policy was not associated with elevated nonuse (adjusted risk ratio = 0.96, P = .06). Although most OPOs are now biopsying nearly all required kidneys, practices still vary widely regarding biopsy-optional kidneys. No correlation was found between OPO-level changes in adjusted biopsy and nonuse rates (ρ = 0.05, P = .70). The OPTN policy has partially standardized biopsy practices without harming kidney utilization.

BACKGROUND:Transplant waitlist registrants in the United States may be delisted because of receipt of a transplant abroad. Although not universally unethical, "travel for transplantation" poses risks to posttransplant care. To better understand this phenomenon, this study identifies temporal trends, geographic patterns, and demographic factors associated with cross-border transplantation. METHODS:Using Scientific Registry of Transplant Recipients data, we identified 818 US waitlist candidates who were removed because of transplantation abroad between 2010 and 2023. We described recipient characteristics overall, by organ, and by top transplant destinations. We used a Cox regression framework to identify characteristics associated with waitlist removal due to transplantation abroad. RESULTS:Transplants abroad averaged 58.4 per year. Incidence peaked at 80 transplants in 2017, with an upward trend after 2021. Kidney transplants made up 92.1% of cases. The most common destinations were the Philippines (19.8%), India (16.5%), Mexico (9.4%), China (8.4%), and Iran (4.4%). India and Mexico experienced the smallest drop-off during the height of the COVID-19 pandemic 2020-2021. Most recipients were US citizens (65.0%) or residents (23.5%). Female (adjusted hazard ratio [aHR], 0.520.610.71; P < 0.001) and Black candidates (aHR, 0.120.180.26; P < 0.001) were less likely to travel abroad compared with Asian candidates (aHR, 5.927.108.52; P < 0.001). Nonresidents (aHR, 6.708.6911.26; P < 0.001) and, among registrations in 2012 or later, nonresidents who traveled to the United States for transplantation (aHR, 27.2738.9155.50; P < 0.001) had a greater chance of undergoing transplantation abroad. CONCLUSIONS:Understanding patterns of international travel for transplantation is key not only for preventing resource drains from destination countries but also for providing adequate posttransplant care for recipients.