Voucher-Based Kidney Donation and Redemption for Future Transplant

Unrecognized opportunities: The landscape of pediatric kidney-paired donation in the United States

BACKGROUND

Pediatric (age < 18 years) kidney transplant (KT) candidates face increasingly complex choices. The 2014 kidney allocation system nearly doubled wait times for pediatric recipients. Given longer wait times and new ways to optimize compatibility, more pediatric candidates may consider kidney-paired donation (KPD). Motivated by this shift and the potential impact of innovations in KPD practice, we studied pediatric KPD procedures in the US from 2008 to 2021.

METHODS

We describe the characteristics and outcomes of pediatric KPD recipients with comparison to pediatric non-KPD living donor kidney transplants (LDKT), pediatric LDKT recipients, and pediatric deceased donor (DDKT) recipients.

RESULTS

Our study cohort includes 4987 pediatric DDKTs, 3447 pediatric non-KPD LDKTs, and 258 pediatric KPD transplants. Fewer centers conducted at least one pediatric KPD procedure compared to those that conducted at least one pediatric LDKT or DDKT procedure (67, 136, and 155 centers, respectively). Five centers performed 31% of the pediatric KPD transplants. After adjustment, there were no differences in graft failure or mortality comparing KPD recipients to non-KPD LDKT, LDKT, or DDKT recipients.

DISCUSSION

We did not observe differences in transplant outcomes comparing pediatric KPD recipients to controls. Considering these results, KPD may be underutilized for pediatric recipients. Pediatric KT centers should consider including KPD in KT candidate education. Further research will be necessary to develop tools that could aid clinicians and families considering the time horizon for future KT procedures, candidate disease and histocompatibility characteristics, and other factors including logistics and donor protections.

Longevity Matching for Living Donor Renal Transplantation

INTRODUCTION

This study identifies the effect of individual donor and recipient characteristics on graft survival in living-donor kidney transplantation (LDKT) using a recently described novel measure, kidney life years (KLYs).

MATERIALS AND METHODS

The Organ Procurement and Transplantation Network/United Network for Organ Sharing database was used to identify first-time kidney-only LDKT recipients between 1987 and 2020 who did not experience death with a functioning graft (DWFG) and were not missing relevant information (n = 87,290). Patient characteristics were evaluated using Cox and multiple regression analyses, with the dependent variable being KLYs. An equation for expected KLYs based on patient characteristics was created using regression coefficients. The equation was validated using bootstrapped Pearson correlations and then applied to the DWFG group for comparison.

RESULTS

Based on statistical significance from Cox and multiple linear regression analyses, 9 of the original 18 variables were selected for inclusion in the equation. Variables with notable impact included HLA match points (0.021 KLYs; 95% CI: [0.019,0.024]; P ≤ .001), Donor Age (-0.030 KLYs; 95% CI: [-0.035,-0.025]; P ≤ .001), and Donor African American Ethnicity (-2.356 KLYs; 95% CI: [-2.552,-2.159]; P ≤ .001). Equation validation was supported, given a negative correlation (r = -0.071; P ≤ .001) between expected KLY change and observed graft failure. Expected KLY change was found to be greater in those who eventually DWFG when compared with all other LDKTs (t = -5.735, P ≤ .001).

CONCLUSIONS

Increasing HLA match points may be more beneficial for graft longevity than minimizing donor age in comparisons using realistic between-donor differences. Additionally, greater average expected KLYs in those who ultimately DWFG may illustrate an opportunity for improved donor-recipient matching.

Mitigating Health Disparities in Transplantation Requires Equity, Not Equality

Despite decades of research and evidence-based mitigation strategies, disparities in access to transplantation persist for all organ types and in all stages of the transplant process. Although some strategies have shown promise for alleviating disparities, others have fallen short of the equity goal by providing the same tools and resources to all rather than tailoring the tools and resources to one's circumstances. Innovative solutions that engage all stakeholders are needed to achieve equity regardless of race, sex, age, socioeconomic status, or geography. Mitigation of disparities is paramount to ensure fair and equitable access for those with end-stage disease and to preserve the trust of the public, upon whom we rely for their willingness to donate organs. In this overview, we present a summary of recent literature demonstrating persistent disparities by stage in the transplant process, along with policies and interventions that have been implemented to combat these disparities and hypotheses for why some strategies have been more effective than others. We conclude with future directions that have been proposed by experts in the field and how these suggested strategies may help us finally arrive at equity in transplantation.

Temporal trends in kidney paired donation in the United States: 2006-2021 UNOS/OPTN database analysis

Kidney paired donation (KPD) is a major innovation that is changing the landscape of kidney transplantation in the United States. We used the 2006-2021 United Network for Organ Sharing data to examine trends over time. KPD is increasing, with 1 in 5 living donor kidney transplants (LDKTs) in 2021 facilitated by KPD. The proportion of LDKT performed via KPD was comparable for non-Whites and Whites. An increasing proportion of KPD transplants are going to non-Whites. End-chain recipients are not identified in the database. To what extent these trends reflect how end-chain kidneys are allocated, as opposed to increase in living donation among minorities, remains unclear. Half the LDKT in 2021 in sensitized (panel reactive antibody ≥ 80%) and highly sensitized (panel reactive antibody ≥ 98%) groups occurred via KPD. Yet, the proportion of KPD transplants performed in sensitized recipients has declined since 2013, likely due to changes in the deceased donor allocation policies and newer KPD strategies such as compatible KPD. In 2021, 40% of the programs reported not performing any KPD transplants. Our study highlights the need for understanding barriers to pursuing and expanding KPD at the center level and the need for more detailed and accurate data collection at the national level.

RapaLink-1 outperforms rapamycin in alleviating allogeneic graft rejection by inhibiting the mTORC1-4E-BP1 pathway in mice

Inhibition of mammalian target of rapamycin (mTOR), which is a component of both mTORC1 and mTORC2, leads to clinical benefits for organ transplant recipients. Pathways to inhibit mTOR include strengthening the association of FKBP12-mTOR or competing with ATP at the active site of mTOR, which have been applied to the design of first- and second-generation mTOR inhibitors, respectively. However, the clinical efficacy of these mTOR inhibitors may be limited by side effects, compensatory activation of kinases and attenuation of feedback inhibition of receptor expression. A new generation of mTOR inhibitors possess a core structure similar to rapamycin and covalently link to mTOR kinase inhibitors, resulting in moderate selectivity and potent inhibition of mTORC1. Since the immunosuppressive potential of this class of compounds remains unknown, our goal is to examine the therapeutic efficacy of a third-generation mTOR inhibitor in organ transplantation. In this study, RapaLink-1 outperformed rapamycin in inhibiting T-cell proliferation and significantly prolonged graft survival time. Mechanistically, the ameliorated rejection induced by RapaLink-1 is associated with a reduction in p-4E-BP1 in T cells, resulting in an elevation in Treg cells alongside a decline in Th1 and Th17 cells. For the first time, these studies demonstrate the effectiveness of third-generation mTOR inhibitors in inhibiting allograft rejection, highlighting the potential of this novel class of mTOR inhibitors for further investigation.

Racial Equity in Living Donor Kidney Transplant Centers, 2008-2018

Importance

It is unclear whether center-level factors are associated with racial equity in living donor kidney transplant (LDKT).

Objective

To evaluate center-level factors and racial equity in LDKT during an 11-year time period.

Design, Setting, and Participants

A retrospective cohort longitudinal study was completed in February 2023, of US transplant centers with at least 12 annual LDKTs from January 1, 2008, to December 31, 2018, identified in the Health Resources Services Administration database and linked to the US Renal Data System and the Scientific Registry of Transplant Recipients.

Main Outcomes and Measures

Observed and model-based estimated Black-White mean LDKT rate ratios (RRs), where an RR of 1 indicates racial equity and values less than 1 indicate a lower rate of LDKT of Black patients compared with White patients. Estimated yearly best-case center-specific LDKT RRs between Black and White individuals, where modifiable center characteristics were set to values that would facilitate access to LDKT.

Results

The final cohorts of patients included 394 625 waitlisted adults, of whom 33.1% were Black and 66.9% were White, and 57 222 adult LDKT recipients, of whom 14.1% were Black and 85.9% were White. Among 89 transplant centers, estimated yearly center-level RRs between Black and White individuals accounting for center and population characteristics ranged from 0.0557 in 2008 to 0.771 in 2018. The yearly median RRs ranged from 0.216 in 2016 to 0.285 in 2010. Model-based estimations for the hypothetical best-case scenario resulted in little change in the minimum RR (from 0.0557 to 0.0549), but a greater positive shift in the maximum RR from 0.771 to 0.895. Relative to the observed 582 LDKT in Black patients and 3837 in White patients, the 2018 hypothetical model estimated an increase of 423 (a 72.7% increase) LDKTs for Black patients and of 1838 (a 47.9% increase) LDKTs for White patients.

Conclusions and Relevance

In this cohort study of patients with kidney failure, no substantial improvement occurred over time either in the observed or the covariate-adjusted estimated RRs. Under the best-case hypothetical estimations, modifying centers' participation in the paired exchange and voucher programs and increased access to public insurance may contribute to improved racial equity in LDKT. Additional work is needed to identify center-level and program-specific strategies to improve racial equity in access to LDKT.

Changing landscape in living kidney donation in Greece

Patients with end-stage renal disease in Greece are facing long waiting times to receive a kidney transplant from a deceased donor. Living kidney donation offers a valuable alternative that provides optimal outcomes and significantly expands the donor pool but still remains relatively underutilised. Developments around the world in the field of kidney transplantation mandate a change in current practice to include additional options for living donation through paired exchange, antibody-incompatible transplantation and other strategies, following careful consideration of the cultural and ethical factors involved in these complex clinical decisions. An increase in living donation rates may be achieved in several ways, including targeted campaigning to overcome potential barriers. Educating clinicians on transplantation will prove as equally important as informing patients and prospective donors but requires training and resources. Adoption of established practices and implementation of new strategies must be tailored to the needs of the Greek donor and recipient population. Local beliefs about donation, perception of associated risk and other social characteristics must be considered in the design of future strategies. Facilitating living donation in a safe environment with appropriate donor and recipient education will form the solid foundation of a new era of kidney transplantation in Greece.

The living kidney donor profile index fails to discriminate allograft survival: implications for its use in kidney paired donation programs

The inclusion of blood group- and human leukocyte antigen-compatible donor and recipient pairs (CPs) in kidney paired donation (KPD) programs is a novel strategy to increase living donor (LD) transplantation. Transplantation from a donor with a better Living Donor Kidney Profile Index (LKDPI) may encourage CP participation in KPD programs. We undertook parallel analyses using data from the Scientific Registry of Transplant Recipients and the Australia and New Zealand Dialysis and Transplant Registry to determine whether the LKDPI discriminates death-censored graft survival (DCGS) between LDs. Discrimination was assessed by the following: (1) the change in the Harrell C statistic with the sequential addition of variables in the LKDPI equation to reference models that included only recipient factors and (2) whether the LKDPI discriminated DCGS among pairs of prognosis-matched LD recipients. The addition of the LKDPI to reference models based on recipient variables increased the C statistic by only 0.02. Among prognosis-matched pairs, the C statistic in Cox models to determine the association of the LKDPI with DCGS was no better than chance alone (0.51 in the Scientific Registry of Transplant Recipient and 0.54 in the Australia and New Zealand Dialysis and Transplant Registry cohorts). We conclude that the LKDPI does not discriminate DCGS and should not be used to promote CP participation in KPD programs.

European Guideline for the Management of Kidney Transplant Patients With HLA Antibodies: By the European Society for Organ Transplantation Working Group

This guideline, from a European Society of Organ Transplantation (ESOT) working group, concerns the management of kidney transplant patients with HLA antibodies. Sensitization should be defined using a virtual parameter such as calculated Reaction Frequency (cRF), which assesses HLA antibodies derived from the actual organ donor population. Highly sensitized patients should be prioritized in kidney allocation schemes and linking allocation schemes may increase opportunities. The use of the ENGAGE 5 ((Bestard et al., Transpl Int, 2021, 34: 1005–1018) system and online calculators for assessing risk is recommended. The Eurotransplant Acceptable Mismatch program should be extended. If strategies for finding a compatible kidney are very unlikely to yield a transplant, desensitization may be considered and should be performed with plasma exchange or immunoadsorption, supplemented with IViG and/or anti-CD20 antibody. Newer therapies, such as imlifidase, may offer alternatives. Few studies compare HLA incompatible transplantation with remaining on the waiting list, and comparisons of morbidity or quality of life do not exist. Kidney paired exchange programs (KEP) should be more widely used and should include unspecified and deceased donors, as well as compatible living donor pairs. The use of a KEP is preferred to desensitization, but highly sensitized patients should not be left on a KEP list indefinitely if the option of a direct incompatible transplant exists.

Organ allocation in pediatric abdominal transplant

Pediatric patients constitute an important group within the general transplant population, given the opportunity to significantly extend their lives with successful transplantation. Children have historically received special consideration under the various abdominal solid organ allocation algorithms, but matching patients with size and weight restrictions with appropriate donors remains an ongoing issue. Here, we describe the historical trends in pediatric organ allocation policies for liver, kidney, intestine, and pancreas transplantation. We also review recent changes to these allocation policies, with particular attention to recent amendments to geographical prioritization, with the dissolution of donor service areas and United Network for Organ Sharing (UNOS) regions and the subsequent creation of acuity circles.

Paired kidney donation: are we going beyond reasonable limits in living-donor transplantation?

The growing demand for transplant kidneys requires strategies to increase organ supply and avoid long waiting periods on the list. The increase in the number of transplants from living donors involves the growth in the use of unrelated donors and paired kidney donation. Most of these transplants are performed in the USA, where they already represent, respectively, 34% and 16% of total transplants from living donors. In Latin America, and especially in Brazil, there is no collective enthusiasm for these modalities, either at the request of transplanters or that of the community, with the region's priority being to increase transplants from deceased donors, which growth can be up to three-fold. Concerning transplants from matched donors, the possible conflicting results between donors can generate public challenges and they risk compromise the concepts of equal opportunities for transplant candidates, with the possibility of generating resistance to organ donation, especially in regions with socioeconomic limitations and disparities in access to qualified health care and education. This donation model involves challenging ethical and logistical issues, which are subject to questionings, starting with an act of exchange between two pairs until reaching embarrassing proposals, which can compromise the altruistic character of organ donation, and thus not be universally incorporated.

Anonymous living liver donor perspectives on the role of family in their donation experience

Anonymous living organ donation is an understudied but rapidly expanding sector in organ transplantation, in which donors choose to donate anonymously to a recipient in need. The family members and close support network of living donors often play a crucial role in the donation process, and their influence likely has a large impact on the decision to donate as well as the donor's physical and psychosocial state. However, there is limited data examining the impact donor families have on the anonymous donor, and in turn, the impact donation has on donors' families. To assess this, we analyzed a semi-structured qualitative interview on living donor experiences with 26 anonymous living liver donors for common themes concerning donor families. Responses surrounding donor families were grouped into three major categories: (1) family reactions to donation, ranging from (a) pride/support, (b) fear/worry, and (c) jealousy/anger; (2) the impact of donation on donor-family relationships, including (a) positive impacts, (b) negative impacts, (c) a positive ripple effect; (3) gaps in institutional support for donor families. This study provides unique information on anonymous living liver donor perceptions related to their families and will help improve existing programs to accommodate donor family needs and cater to donor relationships.