Faculty Bibliography

Hypothermic machine perfusion (HMP) has surged in popularity for donor kidney preservation. Continuous-HMP (cHMP) has shown clear benefits over static cold storage (SCS), whereas randomized trials on short-duration end-ischemic-HMP (eiHMP) have not. We assessed whether HMP modulates injury from increasing cold-preservation-time and analyzed the impact of HMP on short- and long-term outcomes, using OPTN data (2010-2024) on single-kidney-transplant recipients (n=137,835). Multivariable non-linear (restricted cubic spline) regression with interaction terms were used. Median cold-preservation-time was long (17.3hrs,IQR:12.0-22.9), especially in the eiHMP cohort (median=23.0hrs,IQR:17.3-30.5). HMP was associated with significant reductions in DGF (cHMP:aOR=0.484,95%CI=0.467-0.501; eiHMP:aOR=0.459,95%CI=0.435-0.485; transport-only-HMP:aOR=0.535,95%CI=0.512-0.558) and LOS. Interaction analyses revealed HMP mitigated the negative effect of increasing cold-preservation-time compared with SCS. cHMP showed benefit across all cold-preservation-times, whereas eiHMP was beneficial only at longer cold-preservation-times. HMP was also associated with improved 5-year graft and patient survival. In conclusion, HMP reduces the negative impact of each additional hour of cold-preservation-time. Therefore, the treatment effect is not fixed and increases as cold-preservation-time increases, likely explaining the lack of benefit in trials of short-duration eiHMP. The association with improved 5-year graft survival and mortality provides IDEAL stage 4 evidence. This study addresses questions beyond the reach of randomized trials but of clear clinical relevance.

BACKGROUND:Access to liver transplantation (LT) for pediatric registrants is complex and impacted by many factors. Assessing the state of pediatric LT requires understanding the balance between policy, the availability of livers, and the quantity of pediatric patients requiring LT. METHODS:Using Scientific Registry of Transplant Recipients data with Cox regression (to compare rates) and competing risk regression (to compare cumulative incidence), we evaluated pediatric patient characteristics, number of registrants transplanted, and waitlist mortality from (January 1, 2017-February 4, 2020) to (May 1, 2020-June 4, 2023) using the implementation of acuity circles to divide the eras. RESULTS:In 4314 pediatric LT registrants, transplantation rate increased in the post-policy era, compared with the pre-policy era (adjusted hazard ratio [HR], 1.05 1.12 1.20 ; P  < 0.001). When accounting for competing risks, the increase was attenuated and not statistically significant (adjusted subdistribution HR, 0.99 1.06 1.14 ; P  = 0.08); recipients were no more likely to die on the waitlist (adjusted subdistribution HR, 0.78 1.01 1.30 ; P  = 0.99). Importantly, the prevalent pediatric waitlist dropped from 396 (2017) to 225 (2023), the rate of deceased donor LT from pediatric donors increased (weighted HR, 1.20 1.31 1.42 ; P  < 0.001), and access to living donor LT increased, compared with the pre-policy era (weighted HR, 1.11 1.33 1.59 ; P  = 0.002). The transplant rate for pediatric patients did not decrease during the study period despite the introduction of acuity circles. During the study period, the prevalent waitlist shrank, access to LT from pediatric donors increased, and access to living donor LT increased. CONCLUSIONS:Comprehensive assessment following the policy change is necessary to ensure that pediatric candidates maintain priority. Changes in pediatric transplantation are modest and likely related to changes in the pool, rather than to the policy of acuity circles.

INTRODUCTION/BACKGROUND:Following implementation of the U.S. Kidney Allocation System (KAS) in 2014, deceased donor kidneys with a kidney donor profile index (KDPI) < 35% are prioritized for allocation to pediatric candidates. Early post-KAS data suggested this prioritization may have led to more frequent delayed graft function compared to pre-KAS, when pediatric allocation priority was based on donor age < 35 years. We sought to understand the impact of this allocation change on longer-term pediatric kidney transplant outcomes. METHODS:We used SRTR data to identify all deceased donor kidney transplants with pediatric recipients during two eras: "Pre-KAS" (12/1/2009-11/30/2014) and "KAS" (12/1/2015-11/30/2020). We used Cox proportional hazards models to calculate the association between study era and all-cause graft failure (graft failure or death) after adjusting for recipient characteristics. RESULTS:, p = 0.001). Results were similar in sensitivity analyses limited to recipients < 10 years old and recipients alive with a functioning graft 90 days post-transplant. CONCLUSIONS:KDPI-based prioritization of kidneys for pediatric allocation was associated with a lower risk of graft failure compared to donor age-based prioritization. Further refining donor risk scores may enable additional improvements in graft survival.

UNLABELLED:<p>Introduction: Patients with end-stage kidney disease develop cognitive impairment due to comorbidities and dialysis dependence. Among community-dwelling older adults, cognitive (CT) and exercise training (ET) are promising interventions to preserve cognition; these interventions may be tailored for adults undergoing in-center hemodialysis. METHODS:Adult (≥18 years) English-speaking patients undergoing hemodialysis (within 3 months to 3 years of initiation) were enrolled in a 2 × 2 factorial randomized controlled trial: Interventions Made to Preserve Cognitive Function Trial (IMPCT). Participants (n = 121) were block-randomized (September, 2018-February, 2023) into 4 arms: control (SC) (n = 26), intradialytic web-based CT (n = 31), ET using foot peddler (n = 29), and combined CT+ET (n = 35). Participants underwent assessments at baseline and 3 months for executive function, global cognitive function, clinical outcomes, and patient-centered outcomes. We estimated 3-month executive function change (primary outcome) and secondary outcomes using linear regression. RESULTS:There were no differences in 3-month executive function change by arm. Participants exhibited improvement in 3-month global cognitive function in CT+ET arm (Montreal Cognitive Assessment score difference = 2.1, 95% CI: 0.4-3.9), and self-reported 3-month improvement in perceived health change (score difference = 0.8, 95% CI: 0.2-1.4) in ET arm. CONCLUSION/CONCLUSIONS:Clinicians may encourage CT+ET for hemodialysis patients to improve short-term global cognitive function and perceived health. The long-term benefits of these interventions warrant further study. </p>.

Since their early development in the 1980s, Simulated Allocation Models (SAMs) have helped policymakers forecast the impact of proposed allocation policy changes on patient outcomes before implementation. In the United States, models like the Kidney-Pancreas Simulated Allocation Model, Liver Simulated Allocation Model, and Thoracic Simulated Allocation Model have been instrumental in shaping organ allocation policies. Analogous models have emerged globally, including the ETKidney and Eurotransplant Liver Allocation System simulators for the Eurotransplant region, to address country and region-specific allocation challenges. This review categorizes and compares SAMs based on their core assumptions, data, and modeling approaches. We highlight challenges in model validation, the use of synthetic data, and model transparency. While simplifying assumptions are often necessary because of limited data, their influence on results should be clearly communicated to ensure policymakers can interpret model predictions accurately. Furthermore, model validation using both retrospective and prospective data is essential to assess performance under evolving policies. Greater transparency through open-source models, detailed reporting of assumptions, and validation efforts can enhance collaboration, reproducibility, and confidence in transplant research. By providing a global perspective on SAMs, this review aims to inform future research and policy development, promoting evidence-based policy development in organ transplantation.

BACKGROUND/UNASSIGNED:Kidney transplant recipients are at risk for adverse health outcomes. Digital health tools such as wearable accelerometers and continuous glucose monitors (CGMs) can provide detailed, noninvasive tracking of health behaviors and measures, such as physical activity, sleep, and glucose levels, that may offer insights into future health concerns, such as posttransplant diabetes mellitus, cognitive health, and transplant rejection. However, there is limited evidence on the feasibility and acceptability of these devices in kidney transplant candidates older than 50 y. METHODS/UNASSIGNED:This observational cross-sectional pilot study aimed to examine the feasibility of 2 digital health tools: an accelerometer and a continuous glucose monitor. Participants were eligible for the study if they were living donor kidney transplant candidates, aged 50 y or older, had no known cognitive impairments, and could provide informed consent. Participants were asked to wear a CGM and an accelerometer for up to 14 d before their kidney transplant surgery. Device feasibility was quantified by (1) the total time the devices were worn, and (2) the validated System Usability Scale survey administered after the devices were returned. RESULTS/UNASSIGNED:20 participants enrolled in the study (mean age 64 ± 9 y, 25% women, 40% with type 2 diabetes). The median number of days of accelerometer and CGM wear were 7 (interquartile range, 6-10) d and 7 (interquartile range, 7-10) d, respectively. Ninety percent of participants reported a favorable opinion of both devices. Participants wore the CGM 100% of the time and the accelerometer 90% of the time, indicating high adherence. CONCLUSIONS/UNASSIGNED:The use of digital devices was acceptable among kidney transplant candidates aged older than 50 y, paving the way for larger studies to identify early digital biomarkers of health outcomes in this high-risk population.

BACKGROUND:Multiorgan heart and kidney transplants (HKTx) performed for patients with end-stage heart failure and chronic kidney disease have increased in recent years. However, no established protocols exist on whether a heart and kidney from the same donor should be transplanted in the same operation versus 1-2 days apart. METHODS:Using SRTR data 1993-2023, we compared same-donor HKTx recipients with both transplants performed on the same day ("simultaneous") to recipients with kidney transplants performed within 1 day of the heart transplant ("staged"). We examined differences in weighted post-transplant clinical characteristics using average treatment effect. Post-transplant mortality and graft failure was also assessed using Kaplan-Meier curves and instrumental variable analysis adjusted for recipient characteristics and year of transplant. RESULTS:, p < 0.001). Weighted patient mortality, all cause heart failure (ACHF), and all cause kidney failure (ACKF) 4 years post-transplant were slightly lower for simultaneous versus staged HKTx recipients (17.1% vs. 19.9%, 17.2% vs. 20.1%, 20.8% vs. 24.7%). However, instrumental variable analysis found no meaningful differences in adjusted patient survival, ACHF, or ACKF by HKTx type. CONCLUSION/CONCLUSIONS:Simultaneous HKTx recipients have shorter hospital stays, decreased mortality, and higher rates of graft survival post-transplant compared to staged HKTx recipients, which may reflect favorable patient factors that enable both operations to be performed on the same day rather than an inherent benefit of simultaneous HKTx, given equivalent adjusted patient mortality, ACHF, and ACKF.