Faculty Bibliography

Kidneys from donation after circulatory death (DCD) donors historically had lower recovery and utilization than kidneys from donation after brain death (DBD) donors. However, the organ shortage and advances in organ preservation have increased interest in DCD transplantation. We used OPTN data to study temporal changes in U.S. DCD kidney recovery and transplantation. The percent DCD among kidney donors increased from 21.0% (Era1: 2016-2019) to 30.6% (Era2: 2020-2022) and 42.4% (Era3: 2023-2025). By 2025Q2, more than half (50.4%) of kidney donors were DCDs. Wide variability persisted across eras in percent DCD by recovering OPO (Era1 range: 0%-38%, Era2: 0%-49%, Era3: 0.4%-60%) and by transplanting center (Era1 range: 0%-48%, Era2: 0%-58%, Era3: 0%-60%). Transplanted DCD kidneys in Era3 (vs Era1 & Era2) were more likely to have donor age >60, diabetes, hypertension, obesity, and death due to cardiovascular disease or stroke; 86.8% were pumped. Though the recovered DCD kidney nonuse rate rose from 20.8% (Era1) to 29.9% (Era2) and 35.4% (Era3), nonused DCD kidney donors were age and had more comorbidities in Era 3 compared to earlier eras. Given that half of kidney donors are now DCD, refinements in DCD donor selection and management are needed to optimize recovery and utilization.

As hepatitis C virus (HCV) infection is now curable, HCV-positive donor organs have expanded the deceased donor pool. Using OPTN data, we identified adult kidney, liver, heart, and lung candidates listed between 2016-2025 and evaluated rates of consent to accept HCV antibody-positive (Ab+) and HCV viremic (NAT+) organs. Temporal trends were described, and multilevel modified Poisson regression with center-level random effects was used to estimate adjusted risk ratios for candidate factors and quantify center variation using median incidence rate ratios (MIRR). Rates of consent to accept both HCV Ab+ and NAT+ organs rose over time. By the end of follow-up, consent rates for HCV Ab+ organs were 63.1% for kidney, 80.6% for liver, 73.3% for heart, and 72.1% for lung candidates, and consent rates for NAT+ organs were 44.9%, 70.7%, 50.5%, and 46.1%, respectively. Associations between candidate characteristics and consent were small after adjustment for center, whereas center effects were large. For HCV Ab+ organs, MIRRs were 6.31 (kidney), 2.48 (liver), 2.90 (heart), and 4.36 (lung); for NAT+ organs, MIRRs were even higher, 9.65, 3.19, 4.00, and 7.30, respectively, indicating marked between-center variability. Our analyses suggest that access to HCV-positive organs is influenced more by center practices than patient characteristics.

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.