New national allocation policy for deceased donor kidneys in the United States and possible effect on patient outcomes

Implications of Accumulated Cold Time for US Kidney Transplantation Offer Acceptance

BACKGROUND AND OBJECTIVES

Reducing discard is important for the US transplantation system because nearly 20% of the deceased donor kidneys are discarded. One cause for the discards is the avoidance of protracted cold ischemia times. Extended cold ischemia times at transplant are associated with additional risk of graft failure and patient mortality. A preference for local (within the same donor service area) or low-Kidney Donor Risk Index organs, the endogeneity of cold ischemia time during organ allocation, and the use of provisional offers all complicate the analysis of cold ischemia times' influence on kidney acceptance decision making.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using January 2018 to June 2019 Organ Procurement and Transplantation Network data, we modeled the probability of accepting an offer for a kidney after provisional acceptance. We use logistic regression that includes cold ischemia time, Kidney Donor Risk Index, and other covariates selected from literature. Endogeneity of cold ischemia time was treated by a two-stage instrumental variables approach.

RESULTS

Logistic regression results for 3.33 million provisional acceptances from 12,369 donors and 108,313 candidates quantify trade-offs between cold ischemia time at the time of offer acceptance and donor-recipient characteristics. Overall, each additional 2 hours of cold ischemia time affected acceptance for nonlocal and local recipients (odds ratio, 0.75; 95% confidence interval, 0.73 to 0.77, odds ratio, 0.88; 95% confidence interval, 0.86 to 0.91; P<0.001). For Kidney Donor Risk Index >1.75 (Kidney Donor Profile Index >85) kidneys, an additional 2 hours of cold ischemia time for nonlocal and local recipients was associated with acceptance with odds ratio, 0.58; 95% confidence interval, 0.54 to 0.63 (nonlocal) and odds ratio, 0.65; 95% confidence interval, 0.6 to 0.7 (local); P<0.001. The effect of an additional 2 hours of cold ischemia time on acceptance of kidneys with Kidney Donor Risk Index ≤1.75 (Kidney Donor Profile Index ≤85) was less pronounced for nonlocal offers (odds ratio, 0.82; 95% confidence interval, 0.80 to 0.85; P<0.001) and not significant for local offers.

CONCLUSIONS

The acceptability of marginal organs was higher when placements were nearer to the donor and when cold ischemia time was shorter.

Transplantation of Patients With Long Dialysis Vintage in the Current Deceased Donor Kidney Allocation System (KAS)

RATIONALE & OBJECTIVE

In 2014 the wait-time calculation for deceased donor kidney transplantation in the United States was changed from the date of first waitlisting to the date of first maintenance dialysis treatment with the aim of minimizing disparities in access to transplantation. This study examined the impact of this policy on access to transplantation, patient survival, and transplant outcomes among patients treated with maintenance dialysis for a prolonged duration before waitlisting.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Patients identified in the US Renal Data System between 2008 and 2018 aged 18-70 years and in the 95th percentile of dialysis treatment duration (≥6.5 years) before waitlisting.

EXPOSURE

Waitlisting for transplantation before versus after implementation of the policy.

OUTCOME

Time from date of waitlisting to deceased donor transplantation and death, and from date of transplantation to all cause graft loss.

ANALYTICAL APPROACH

Univariate and multivariable time to event analyses.

RESULTS

Patients waitlisted after the policy change had a higher likelihood of deceased donor transplantation (HR, 3.12 [95% CI, 2.90-3.37]) and lower risk of death (HR, 0.74 [95% CI, 0.63-0.87]). The risk of graft loss was lower in the post-kidney allocation system (KAS) cohort (HR, 0.66 [95% CI, 0.55-0.80]). The proportion of adult patients treated with dialysis ≥6.5 years who were never waitlisted for transplantation remained high (73%) and did not decrease after the policy implementation.

LIMITATIONS

Cannot determine causality in this observational study.

CONCLUSIONS

The policy change was associated with an increase in deceased donor transplantation and marked improvement in patient survival for patients waitlisted after long periods of dialysis treatment without decreasing the utility of available deceased donor kidney supply. The policy was not associated with increased waitlisting of this disadvantaged population.

Deceased Donor Characteristics and Kidney Transplant Outcomes

Kidney transplantation is the therapy of choice for people living with kidney failure who are suitable for surgery. However, the disparity between supply versus demand for organs means many either die or are removed from the waiting-list before receiving a kidney allograft. Reducing unnecessary discard of deceased donor kidneys is important to maximize utilization of a scarce and valuable resource but requires nuanced decision-making. Accepting kidneys from deceased donors with heterogenous characteristics for waitlisted kidney transplant candidates, often in the context of time-pressured decision-making, requires an understanding of the association between donor characteristics and kidney transplant outcomes. Deceased donor clinical factors can impact patient and/or kidney allograft survival but risk-versus-benefit deliberation must be balanced against the morbidity and mortality associated with remaining on the waiting-list. In this article, the association between deceased kidney donor characteristics and post kidney transplant outcomes for the recipient are reviewed. While translating this evidence to individual kidney transplant candidates is a challenge, emerging strategies to improve this process will be discussed. Fundamentally, tools and guidelines to inform decision-making when considering deceased donor kidney offers will be valuable to both professionals and patients.

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.

Age-dependent Sex Differences in Graft Loss After Kidney Transplantation

BACKGROUND

Sex differences in kidney graft loss rates were reported in the United States. Whether these differences are present in other countries is unknown.

METHODS

We estimated the association between recipient sex and death-censored graft loss in patients of all ages recorded in the Scientific Registry of Transplant Recipients, Australia and New Zealand Dialysis and Transplant Registry, and Collaborative Transplant Study registries who received a first deceased donor kidney transplant (1988-2019). We used multivariable Cox regression models, accounting for the modifying effects of donor sex and recipient age, in each registry separately; results were combined using individual patient data meta-analysis.

RESULTS

We analyzed 438 585 patients. Young female patients 13-24 y old had the highest crude graft loss rates (female donor: 5.66; male donor: 5.50 per 100 person-years). Among young recipients of male donors, females showed higher graft loss risks than males (0-12 y: adjusted hazard ratio [aHR] 1.42, (95% confidence interval [CI], 1.17-1.73); 13-24 y: 1.24 (1.17-1.32); 25-44 y: 1.09 (1.06-1.13)). When the donor was female, there were no significant differences by recipient sex among those of age <45 y; however, the aHR for females was 0.93 (0.89-0.98) in 45-59 y-old and 0.89 (0.86-0.93) in ≥ 60 y-old recipients. Findings were similar for all 3 registries in most age intervals; statistically significant heterogeneity was seen only among 13-24-y-old recipients of a female donor (I2 = 71.5%, P = 0.03).

CONCLUSIONS

There is an association between recipient sex and kidney transplantation survival that is modified by recipient age and donor sex.

Transplantation Mediates Much of the Racial Disparity in Survival from Childhood-Onset Kidney Failure

BACKGROUND

The role of kidney transplantation in differential survival in Black and White patients with childhood-onset kidney failure is unexplored.

METHODS

We analyzed 30-year cohort data of children beginning RRT before 18 years of age between January 1980 and December 2017 (n=28,337) in the US Renal Data System. Cox regression identified transplant factors associated with survival by race. The survival mediational g-formula estimated the excess mortality among Black patients that could be eliminated if an intervention equalized their time with a transplant to that of White patients.

RESULTS

Black children comprised 24% of the cohort and their crude 30-year survival was 39% compared with 57% for White children (log rank P<0.001). Black children had 45% higher risk of death (adjusted hazard ratio [aHR], 1.45; 95% confidence interval [95% CI], 1.36 to 1.54), 31% lower incidence of first transplant (aHR, 0.69; 95% CI, 0.67 to 0.72), and 39% lower incidence of second transplant (aHR, 0.61; 95% CI, 0.57 to 0.65). Children and young adults are likely to require multiple transplants, yet even after their first transplant, Black patients had 11% fewer total transplants (adjusted incidence rate ratio [aIRR], 0.89; 95% CI, 0.86 to 0.92). In Black patients, grafts failed earlier after first and second transplants. Overall, Black patients spent 24% less of their RRT time with a transplant than did White patients (aIRR, 0.76; 95% CI, 0.74 to 0.78). Transplantation compared with dialysis strongly protected against death (aHR, 0.28; 95% CI, 0.16 to 0.48) by time-varying analysis. Mediation analyses estimated that equalizing transplant duration could prevent 35% (P<0.001) of excess deaths in Black patients.

CONCLUSIONS

Equalizing time with a functioning transplant for Black patients may equalize survival of childhood-onset ESKD with White patients.

Kidney Organ Allocation System: How to Be Fair

Transplantation is a life-saving medical intervention that unfortunately is constrained by scarcity of available organs. An ideal system for allocating organs should seek to achieve the greatest good for the greatest number of people. It also must be fair and not disadvantage certain populations. However, policies aimed at reducing disparities also must be balanced with considerations of utility (graft outcomes), cost, efficiency, and any adverse effects on organ utilization. Here, we discuss the ethical challenges of creating a fair and equitable organ allocation system, focusing on the principles governing deceased donor kidney transplant waitlists around the world. The kidney organ allocation systems in the United States, Australia, and Hong Kong are used as illustrations.

The Kidney Transplant Equity Index: Improving Racial and Ethnic Minority Access to Transplantation

OBJECTIVES

To develop a scalable metric which quantifies kidney transplant (KT) centers' performance providing equitable access to KT for minority patients, based on the individualized pre-listing prevalence of End-Stage Renal Disease (ESRD).

SUMMARY BACKGROUND DATA

Racial and ethnic disparities for access to transplant in patients with ESRD are well described; however, variation in care among KT centers remains unknown. Furthermore, no mechanism exists that quantifies how well a KT center provides equitable access to KT for minority patients with ESRD.

METHODS

From 2013-2018, custom datasets from the United States Renal Data System and United Network for Organ Sharing were merged to calculate the Kidney Transplant Equity Index (KTEI), defined as: the number of minority patients transplanted at a center relative to the prevalence of minority patients with ESRD in each center's health service area. Markers of socioeconomic status (SES) and recipient outcomes were compared between high and low KTEI centers.

RESULTS

249 transplant centers performed 111,959 KTs relative to 475,914 non-transplanted patients with ESRD. High KTEI centers performed more KTs for Black (105.5 vs. 24, P<0.001), Hispanic (55.5 vs. 7, P<0.001), and American Indian (1.0 vs. 0.0, P<0.001) patients than low KTEI centers. In addition, high KTEI centers transplanted more patients with higher unemployment (52 vs. 44, P<0.001), worse social deprivation (53 vs. 46, P<0.001), and lower educational attainment (52 vs. 43, P<0.001). While providing increased access to transplant for minority and low SES populations, high KTEI centers had improved patient survival (HR: 0.86, 95% CI: 0.77-0.95).

CONCLUSIONS

The KTEI is the first metric to quantify minority access to KT incorporating the pre-listing ESRD prevalence individualized to transplant centers. KTEIs uncover significant national variation in transplant practices and identify highly equitable centers. This novel metric should be used to disseminate best practices for minority and low socioeconomic patients with ESRD.

Kidney Retransplantation after Graft Failure: Variables Influencing Long-Term Survival

Background

There is an increasing demand for kidney retransplantation. Most studies report inferior outcomes compared to primary transplantation, consequently feeding an ethical dilemma in the context of chronic organ shortage.

Objective

To assess variables influencing long-term graft survival after kidney retransplantation. Material and Methods. All patients transplanted at our center between 2000 and 2016 were analyzed retrospectively. Survival was estimated with the Kaplan–Meier method, and risk factors were identified using multiple Cox regression.

Results

We performed 1,376 primary kidney transplantations and 222 retransplantations. The rate of retransplantation was 67.8% after the first graft loss, with a comparable 10-year graft survival compared to primary transplantation (67% vs. 64%, p=0.104) but an inferior graft survival thereafter (log-rank p=0.026). Independent risk factors for graft survival in retransplantation were age ≥ 50 years, time on dialysis ≥1 year, previous graft survival <2 years, ≥1 mild comorbidity in the Charlson–Deyo index, active smoking, and life-threatening complications (Clavien–Dindo grade IV) at first transplantation.

Conclusion

Graft survival is comparable for first and second kidney transplantation within the first 10 years. Risk factors for poor outcomes after retransplantation are previous graft survival, dialysis time after graft failure, recipient age, comorbidities, and smoking. Patients with transplant failure should have access to retransplantation as early as possible.

Evaluation of Expanded Criteria Donors Using the Kidney Donor Profile Index and the Preimplantation Renal Biopsy

The increasing comorbidity of kidney transplant (KT) donors make it necessary to develop scores to correctly assess the quality of kidney grafts. This study analyzes the usefulness of the preimplantation biopsy and the Kidney Donor Profile Index (KDPI) as indicators of KT survival from expanded criteria donors (ECD). Retrospective study of KT in our center between January 2010 to June 2019 who received a kidney from an ECD and underwent a preimplantation biopsy. 266 KT were included. Graft survival was categorized by KDPI quartiles: Q1 = 86%, Q2 = 95%, Q3 = 99% and Q4 = 100%. KT from KDPI Q1 presented better survival (p = 0.003) and Q4 donors had worse renal function (p = 0.018) and poorer glomerular filtration rate (3rd month; p = 0.017, 1st year; p = 0.010). KT survival was analyzed according to KDPI quartile and preimplantation biopsy score simultaneously: Q1 donors with biopsy score ≤3 had the best survival, especially comparing against Q3 with a biopsy score >3 and Q4 donors (p = 0.014). In multivariable analysis, hyaline arteriopathy, glomerulosclerosis, and KDPI Q4 were predictors for graft survival. High KDPI and a greater histological injury in the preimplantation biopsy, especially glomerular and vascular lesions, were related to a higher rate of KT loss from ECD.

Examining utilization of kidneys as a function of procurement performance

Questions have arisen around new metrics for organ procurement organizations (OPO) due to the perception that low-performing OPOs may be limited by local centers' acceptance of marginal organs. We reviewed 2013-2019 Organ Procurement and Transplantation Network (OTPN) and National Centers for Health Statistics (NCHS) data to explore the relationship between objectively measured OPO performance and utilization of deceased donor kidneys. We found that although donor recovery declined with rising age and kidney donor profile index (KDPI), OPO performance differences were evident within each age/KDPI group. By contrast, the number of discards per donor did not vary with OPO performance. Centers in donor service areas (DSAs) with lower-performing OPOs had higher local utilization and greater import of high-KDPI kidneys than did those with higher-performing OPOs. Lower rates of donor availability relative to waitlist additions may contribute to observed center acceptance behavior. Differences in center-level performance were highly visible in Scientific Registry of Transplant Recipients (SRTR) organ acceptance metrics, while SRTR OPO metrics did not detect large or persistent variation in procurement performance. Cumulatively, our findings suggest that objective measures of procurement performance can inform discussions of organ utilization, allowing for alignment of metrics in all elements of the procurement-transplantation system.

Apolipoprotein L1 Opinions of African American Living Kidney Donors, Kidney Transplant Patients, and Nonpatients

INTRODUCTION

The discovery of apolipoprotein L1 (ApoL1) has raised important ethical and clinical questions about genetic testing in the context of living and deceased kidney donation. Largely missing from this discussion are the perspectives of those African Americans (AA) most likely to be impacted by ApoL1 testing.

METHODS

We surveyed 331 AA potential and former living kidney donors (LKDs), kidney transplant candidates and recipients, and nonpatients at three United States transplant programs about their ApoL1 testing attitudes.

RESULTS

Overall, 72% felt that transplant programs should offer ApoL1 testing to AA potential LKDs. If a potential LKD has the high-risk genotype, 79% felt that the LKD should be allowed to make their own donation decision or participate in shared decision-making with transplant doctors. More than half of the potential LKDs (58%) would undergo ApoL1 testing and 81% of former LKDs would take the test now if offered. Most transplant candidates expressed a low likelihood of accepting a kidney from a LKD (79%) or a deceased donor (67%) with the high-risk genotype.

CONCLUSIONS

There is strong support among LKDs and transplant patients for ApoL1 testing when evaluating potential kidney donors of African ancestry. Inclusion of AA stakeholders in developing guidelines and educational programs for ApoL1 testing is critical.

Examination of Racial and Socioeconomic Disparity in Use of Nondirected Kidney Donation in the US

BACKGROUND

Nondirected donor (NDD) kidney transplant (NDDKT) continues to improve organ access for waitlisted candidates. Although NDDs are becoming increasingly common, there has been no contemporary evaluation of NDD allograft use, and it is vital to understand sociodemographic, as well as center-level, use across the US.

STUDY DESIGN

Using national data from the Scientific Registry for Transplant Recipients, this study characterized NDDs, NDDKT recipients, and center-level distribution of NDDKT. Directed donor and NDD characteristics were compared using Fisher's exact and Wilcoxon rank-sum tests for categorical and continuous variables, respectively. Multivariable logistic regression was used to identify characteristics associated with receiving NDDKT, and center distribution of NDDKT was assessed using the Gini coefficient.

RESULTS

NDDKT increased from 1.4% (n = 154) of all living donor kidney transplants in 2010 to 6.5% (n = 338) in 2020. Compared with directed living donors, NDDs were older (median [IQR], 44 [33 to 54] vs 43 [33 to 52], p < 0.01), more often male (40.2% vs 36.7%, p < 0.001), and White (91.4% vs 69.5%, p < 0.001). White adult candidates were more likely to receive NDDKT compared with Black (adjusted odds ratio [aOR], 0.300.340.39, p < 0.001), Hispanic/Latino (aOR, 0.360.420.48, p < 0.001), and Other (aOR, 0.410.470.55, p < 0.001) candidates. Black pediatric candidates had lower odds of receiving NDDKT (aOR, 0.090.220.54, p = 0.02). The proportion of centers performing NDDKT has increased from 2010 to 2020 (Gini = 0.77 vs 0.68).

CONCLUSIONS

Although more centers are performing NDDKT, racial disparities persist among NDDs and NDDKT recipients. Continued effort is needed to recruit living kidney donors and improve access to living donation for minority groups in the US. (J Am Coll Surg 2022;234:000-00. © 2022 by the American College of Surgeons).

Stability of Anti-HLA Sensitization Profiles in Highly Sensitized Kidney Transplantation Candidates: Toward a Rational Serological Testing Strategy

BACKGROUND

Highly sensitized (HS) anti-HLA patients awaiting kidney transplantation benefit from specific allocation programs. Serological monitoring at 3-mo intervals is recommended to prevent unexpected positive crossmatch (XM), but this strategy is not evidence-based. Therefore, we assessed its relevance when using single-antigen flow bead (SAFB) and screening flow bead (SFB) assays.

METHODS

We included 166 HS patients awaiting a transplant and assessed their SAFB profile during the year preceding their inclusion. Anti-HLA antibodies were evaluated by SAFB assay and compared within patients as serum pairs at 3, 6, and 9 mo. We assessed the performance of SFB for detecting changes in SAFB profiles with 35 serum pairs.

RESULTS

On comparing 354, 218, and 107 serum pairs at 3, 6, and 9 mo, respectively, only 0.6%, 0.7%, and 1% of all antigens tested exceeded for the first time the unacceptable antigen threshold (mean fluorescence intensity ≥2000) in the most recent sample. Irrespective of the follow-up period, the calculated panel-reactive antibodies increased by a mean of 1%, and there was no significant increase in the proportion of donors at risk for positivity of flow- or complement-dependent cytotoxicity XM. The SFB did not accurately detect the variations of SAFB profiles.

CONCLUSIONS

Changes in HS patient profiles are anecdotal and show little association with transplant access or risk for positive XM. Less-frequent monitoring in HS patients should be considered to improve cost-effectiveness without affecting transplant safety.

The Role of Procurement Biopsies in Kidney Acceptance Decision Making and Kidney Discard: Perceptions of Physicians, Nurse Coordinators, and OPO Staff and Directors

Procurement biopsies suffer from challenges with quality and reproducibility and are linked to kidney discard. Nonetheless, procurement biopsies are obtained for the majority of kidneys in the United States, and biopsy findings are commonly relied upon in kidney acceptance decisions.

Human leukocyte antigen antibody sensitization, lung transplantation, and health equity

Women with advanced lung disease, particularly Black and Hispanic women, are more likely than other patients to have anti-human leukocyte (HLA) antibodies against potential donors. Sensitized patients, especially those who are highly sensitized, are less likely to be listed for lung transplant or to be considered candidates for mechanical circulatory support. They are also at higher risk for waitlist death. Institutional variability in approach to HLA antibody screening and pre-transplant management creates barriers to transplant that disproportionately impact Black and Hispanic women. At the same time, our understanding of the clinical significance of pre-transplant antibodies lags behind the sophistication of our screening assays. The lack of national data on pre- and post-transplant HLA antibody characteristics hinders research into strategies to mitigate concerns about these antibodies and to improve access to lung transplant among sensitized patients. Ongoing work should be done to identify clinically higher risk antibodies, to develop better strategies for safely crossing antibodies at the time of transplant, and to model changes in lung allocation to give priority to sensitized patients for a HLA antibody-antigen compatible donors. These priorities mandate a commitment to collaborative, multicenter research and to real time translation of results to clinical practice and allocation policy.

Time to Move on: HLA Matching Should Be Reconsidered in Modern Deceased Donor Kidney Allocation

HLA matching has been the cornerstone of deceased donor kidney allocation policies worldwide but can lead to racial inequity. Although HLA matching has been shown to improve clinical outcomes, the long-term impacts of nonallogenic factors are being increasingly recognized. This has led some transplant programs to include points for nonallogenic factors, for example, age. Our study looks at long-term graft and patient outcomes based on allocation cohorts rather than individual number of HLA mismatches.

Patient and Clinician Perceptions of Informed Consent and Decision Making About Accepting KDPI > 85 Kidneys

Supplemental Digital Content is available in the text.

Background.

Although the impact of the kidney donor profile index (KDPI) on kidney discard is well researched, less is known about how patients make decisions about whether to give consent for KDPI > 85 kidney offers.

Methods.

We conducted in-depth, semistructured interviews with 16 transplant recipients, 15 transplant candidates, and 23 clinicians (transplant surgeons, nephrologists, and nurse coordinators) to assess and compare perceptions of transplant education, informed consent for KDPI > 85 kidneys‚ and the decision-making process for accepting kidney offers. Thematic analysis was used to analyze qualitative data.

Results.

Four themes emerged: (1) patients reported uncertainty about the meaning of KDPI or could not recall information about KDPI; (2) patients reported uncertainty about their KDPI > 85 consent status and a limited role in KDPI > 85 consent decision making; (3) patients’ reported willingness to consider KDPI > 85 kidneys depended on their age, health status, and experiences with dialysis, and thus it changed over time; (4) patients’ underestimated the survival benefit of transplantation compared with dialysis, which could affect their KDPI > 85 consent decision making.

Conclusions.

To better support patients’ informed decision making about accepting KDPI > 85 kidneys, centers must ensure that all patients receive education about the trade-offs between accepting a KDPI > 85 kidney and remaining on dialysis. Additionally, education about KDPI and discussions about informed consent for KDPI > 85 kidneys must be repeated at multiple time points while patients are on the waiting list.

First Asian Kidney Donor Profile Index (KDPI) and Estimated Post-Transplant Survival (EPTS) Models, With Validation Against US Models in Thai Population

INTRODUCTION

Differences in transplant characteristics limit the application of kidney donor profile index (KDPI) and estimated post-transplant survival (EPTS) models developed in Western countries to Asian populations.

METHODS

We analyzed data of the Thai Transplant Registry and the Thai Red Cross Society on 2,558 DDKTs performed between 2001 and 2014. Thai KDPI and EPTS models were developed using Cox regression, and validation against the US models.

RESULTS

Thai KDPI was developed based on 7 donor factors: age, height, best estimated glomerular filtration rate, diabetes mellitus, hypertension, cerebrovascular accident, and adrenaline infusion. The Thai and US donor risk index had comparable predictive abilities for transplant survival (C-statistics 0.5871 vs 0.5548; P = 0.429). KTs from donors with a US KDPI > 70% demonstrated significantly worse 5-year transplant survival. The Thai EPTS model was developed from 4 recipient factors: age, body weight, diabetes mellitus, and hepatitis C infection. The C-statistics of the Thai and US EPTS models were comparable (0.5924 vs 0.6039; P = 0.360). A US EPTS > 70% was revealed in only 2.5% of our cohort.

CONCLUSIONS

The first simplified KDPI and EPTS models for an Asian population were developed. Our models are available at www.thai-kdpi-epts.org. This article is protected by copyright. All rights reserved.

A Historical Cohort in Kidney Transplantation: 55-Year Follow-Up of 72 HLA-Identical, Donor-Recipient Pairs

The impact of HLA matching on graft survival has been well characterized in renal transplantation, with a higher degree of matching associated with superior graft survival. Additionally, living donor grafts are known to confer superior survival compared to those from deceased donors. The purpose of this study is to report our multi-decade institutional experience and outcomes for patients who received HLA-identical living donor grafts, which represent the most favorable scenario in kidney transplantation. We conducted a retrospective analysis of these graft recipients performed at a Duke University Medical Center between the years of 1965 and 2002. The recipients demonstrated excellent graft and patient survival outcomes, superior to a contemporary cohort, with median patient and graft survival of 24.2 and 30.9 years, respectively, among Duke recipients vs. 16.1 and 16.0 years in a cohort derived from national data. This study offers a broad perspective on the importance of HLA matching and graft type, and demonstrates a historical best-case-scenario in renal transplantation.

Current State of Multiorgan Transplantation and Implications for Future Practice and Policy

The incidence of kidney dysfunction has increased in liver transplant and heart transplant candidates, reflecting a changing patient population and allocation policies that prioritize the most urgent candidates. A higher burden of pretransplant kidney dysfunction has resulted in a substantial rise in the utilization of multiorgan transplantation (MOT). Owing to a shortage of available deceased donor kidneys, the increased use of MOT has the potential to disadvantage kidney-alone transplant candidates, as current allocation policies generally provide priority for MOT candidates above all kidney-alone transplant candidates. In this review, the implications of kidney disease in liver transplant and heart transplant candidates is reviewed, and current policies used to allocate organs are discussed. Important ethical considerations pertaining to MOT allocation are examined, and future policy modifications that may improve both equity and utility in MOT policy are considered.

Predicting Kidney Discard Using Machine Learning

BACKGROUND

Despite the kidney supply shortage, 18%-20% of deceased donor kidneys are discarded annually in the United States. In 2018, 3569 kidneys were discarded.

METHODS

We compared machine learning (ML) techniques to identify kidneys at risk of discard at the time of match run and after biopsy and machine perfusion results become available. The cohort consisted of adult deceased donor kidneys donated between December 4, 2014, and July 1, 2019. The studied ML models included Random Forests (RF), Adaptive Boosting (AdaBoost), Neural Networks (NNet), Support Vector Machines (SVM), and K-nearest Neighbors (KNN). In addition, a Logistic Regression (LR) model was fitted and used for comparison with the ML models' performance.

RESULTS

RF outperformed other ML models. Of 8036 discarded kidneys in the test dataset, LR correctly classified 3422 kidneys, whereas RF correctly classified 4762 kidneys (area under the receiver operative curve [AUC]: 0.85 versus 0.888, and balanced accuracy: 0.681 versus 0.759). For the kidneys with kidney donor profile index of >85% (6079 total), RF significantly outperformed LR in classifying discard and transplant prediction (AUC: 0.814 versus 0.717, and balanced accuracy: 0.732 versus 0.657). More than 388 kidneys were correctly classified using RF. Including biopsy and machine perfusion variables improved the performance of LR and RF (LR's AUC: 0.888 and balanced accuracy: 0.74 versus RF's AUC: 0.904 and balanced accuracy: 0.775).

CONCLUSIONS

Kidneys that are at risk of discard can be more accurately identified using ML techniques such as RF.

Optimal Immunosuppression Strategy in the Sensitized Kidney Transplant Recipient

Patients with previous sensitization events against anti-human leukocyte antigens (HLA) often have circulating anti-HLA antibodies. Following organ transplantation, sensitized patients have higher rates of antibody-mediated rejection (AMR) compared to those who are non-sensitized. More stringent donor matching is required for these patients, which results in a reduced donor pool and increased time on the waitlist. Current approaches for sensitized patients focus on reducing preformed antibodies that preclude transplantation; however, this type of desensitization does not modulate the primed immune response in sensitized patients. Thus, an optimized maintenance immunosuppressive regimen is necessary for highly sensitized patients, which may be distinct from non-sensitized patients. In this review, we will discuss the currently available therapeutic options for induction, maintenance, and adjuvant immunosuppression for sensitized patients.

Disparity in the access to kidney transplantation for sensitized patients in the state of Sao Paulo-Brazil

Highly sensitized (HS) patients accumulate on deceased donor kidney transplantation (DDKT) waitlists worldwide due to matching difficulty and inequity of allocation policies. Current situation of HS patients on KT waitlist in Brazil has not been published. All patients enrolled on the KT waitlist of the State of São Paulo from 2002 to 2017 were retrospectively assessed. Patients were divided into eight groups according to their degree of sensitization, PRA of 0%, >0-40%, >40-80%, >80-85%, >85-90%, >90-95%, >95-98% and > 98%. Cumulative incidence curves for transplantation or mortality/removal from waitlist were estimated by competing risk. Among 50,249 waitlisted candidates, 1247 prioritized, 2467 with age < 18 or > 75 years and 4152 submitted to living-donor KT were excluded from the analysis, remaining 42,383 patients. There were 29,664(70%) PRA 0%, 5611(13.2%) PRA > 0-40%, 3442(8.2%) PRA > 40-80%, 507(1.2%) PRA > 80-85%, 564(1.3%) PRA > 85-90%, 825(1.9%) PRA >90-95%, 859(2%) PRA > 95-98% and 911(2.2%) PRA > 98%. There was a progressive increase in the need of prioritization, waiting time for KT or on waitlist and time on dialysis as PRA increased (p < 0.001). Probability of DDKT clearly increased as PRA decreased so that PRA 0% candidates were much more likely to be transplanted compared to PRA > 98% patients(HR:13.02, p < 0.001). Waiting list mortality/removal was higher among PRA > 0-40%(HR1.05,p = 0.03), PRA > 90-95%(HR:1.10,p = 0.05), PRA > 95-98%(HR:1.26,p < 0.001) and PRA > 98%(HR:1.09,p = 0.05) patients compared to PRA zero candidates. HS patients in Sao Paulo-Brazil required greater prioritization due to lack of venous access, longer dialysis and waitlist times, lower probability of DDKT and higher rates of waitlist mortality/removal. We confirmed the disparity of access to KT among HS patients in Sao Paulo-Brazil, indicating the need of new strategies that optimize transplantation for this subcategory of patients.

Late first acute rejection in pediatric kidney transplantation: A North American Pediatric Renal Trials and Collaborative Studies special study

Rates of early AR in pediatric kidney transplantation have declined in every era but the most recent NAPRTCS cohort has shown an increase in late first AR rates. We hypothesized this was due to an increased proportion of deceased donor utilization and early steroid taper utilization. Using the NAPRTCS database, we compared the most recent three cohorts of patients transplanted between 2002-2006, 2007-2011, and 2012-2017. To determine variables that predict late first AR, we used two multivariable models: a standard Cox regression model and LASSO model. From the LASSO model, deceased donor source (P = .002), higher recipient age (P = .019), black race (P = .010), and transplant cohort 2012-17 (P = .014) were all significant predictors of more late first AR. On standard Cox regression analysis, those same variables, minus donor source, were significant, in addition to mycophenolates usage (P = .007) and lower eGFR at 12 months (P = .02). The most recent 2012-2017 cohort remains an independently significant risk factor for late first AR, suggesting unmeasured variables. Further research is needed to determine whether these higher late first AR rates will impact long-term graft survival in the most recent cohort.

Computational Eurotransplant kidney allocation simulations demonstrate the feasibility and benefit of T-cell epitope matching

The EuroTransplant Kidney Allocation System (ETKAS) aims at allocating organs to patients on the waiting list fairly whilst optimizing HLA match grades. ETKAS currently considers the number of HLA-A, -B, -DR mismatches. Evidently, epitope matching is biologically and clinically more relevant. We here executed ETKAS-based computer simulations to evaluate the impact of epitope matching on allocation and compared the strategies. A virtual population of 400,000 individuals was generated using the National Marrow Donor Program (NMDP) haplotype frequency dataset of 2011. Using this population, a waiting list of 10,400 patients was constructed and maintained during simulation, matching the 2015 Eurotransplant Annual Report characteristics. Unacceptable antigens were assigned randomly relative to their frequency using HLAMatchmaker. Over 22,600 kidneys were allocated in 10 years in triplicate using Markov Chain Monte Carlo simulations on 32-CPU-core cloud-computing instances. T-cell epitopes were calculated using the www.pirche.com portal. Waiting list effects were evaluated against ETKAS for five epitope matching scenarios. Baseline simulations of ETKAS slightly overestimated reported average HLA match grades. The best balanced scenario maintained prioritisation of HLA A-B-DR fully matched donors while replacing the HLA match grade by PIRCHE-II score and exchanging the HLA mismatch probability (MMP) by epitope MMP. This setup showed no considerable impact on kidney exchange rates and waiting time. PIRCHE-II scores improved, whereas the average HLA match grade diminishes slightly, yet leading to an improved estimated graft survival. We conclude that epitope-based matching in deceased donor kidney allocation is feasible while maintaining equal balances on the waiting list.

Kidney transplantation is the best treatment option for patients suffering permanent loss of kidney function. High degrees of histocompatibility between patients and organ donors improve long-term function of transplanted kidneys. In order to ensure fair access to transplantation whilst maximising utility of each donor kidney, organ allocation organizations established recipient waiting lists and well-balanced algorithms to allocate donors to patients. Changing the allocation algorithms requires careful consideration of side-effects to avoid disadvantages of certain groups of patients. In this study, we evaluated the feasibility of modifying the existing Eurotransplant Kidney Allocation System (ETKAS) to incorporate indirect T-cell epitope matching, a novel technique for assessing functional histocompatibility. Using Markov chain Monte Carlo simulations, we compared the modified allocation to the current algorithm and found an overall improvement of indirect T cell epitope compatibility. Simultaneously, we observed no negative impact on allocation fairness or waiting times. Our simulation framework may serve as a basis to evaluate further adjustments to ETKAS in the future. From our results, we conclude that epitope matching can be safely incorporated into ETKAS.

Implementation of donation after circulatory death kidney transplantation can safely enlarge the donor pool: A systematic review and meta-analysis

BACKGROUND

Donation after circulatory death (DCD) kidney transplantation has been introduced to address organ shortage. However, DCD kidneys are not accepted worldwide due to concerns about inferior quality. To investigate whether these concerns are justified, we performed a systematic review and meta-analysis to investigate DCD graft outcomes compared to donation after brain death (DBD).

MATERIALS AND METHODS

EMBASE, Medline, Cochrane, Web of Science and Google Scholar were searched from database inception until September 2020. Exclusion criteria were studies reporting on pediatric/dual kidney transplants, multi-organ transplants or studies including normothermic perfusion techniques. The primary outcome was graft survival. Secondary outcomes were primary non-function (PNF), delayed graft function (DGF), 3-months biopsy-proven acute rejection (BPAR), 1-year estimated Glomerular Filtration Rate (eGFR), patient survival, and urologic complications. A random-effects model was used for meta-analysis. Meta-regression analysis was performed in case of high between-study heterogeneity.

RESULTS

Fifty-one studies were included, comprising 73,454 DCD and 518,229 DBD recipients. One-year graft loss was increased in DCD recipients (death-censored: risk ratio (RR) 1.10 (95%-confidence interval (CI) 1.04-1.16), all-cause: RR 1.13 (95%-CI 1.08-1.19)). Ten-year graft loss was similar to DBD (death-censored: RR 1.02 (95%-CI 0.92-1.13), all-cause: RR 1.03 (95%-CI 0.94-1.13)). DCD recipients had an increased risk of PNF (RR 1.43 (95%-CI 1.26-1.62)), DGF (RR 2.02 (95%-CI 1.88-2.16)), and 1-year mortality (RR 1.10 (95%-CI 1.01-1.21)). No differences were observed for 3-months BPAR, ureter stenosis/leakage, 1-year eGFR and 10-year mortality.

CONCLUSION

Long-term DCD kidney transplant outcomes are similar to DBD despite a higher risk of PNF, DGF, and a 13% increased risk of graft loss in the first year after transplantation. These results should encourage implementation of DCD programs.

A kidney discard decision strategy based on zero-time histology analysis could lead to an unjustified increase in the organ turndown rate among ECD

The utility of zero-time kidney biopsies (KB) in deciding to accept expanded criteria donor (ECD) kidneys remains controversial. However, zero-time histology is one of the main causes for discarding kidneys in the United States. In a single-centre study, we examined the utility and impact on outcome of the use of frozen section zero-time KB among ECD. Ninety-two zero-time KB were analysed for accept/discard decision between 2005 and 2015 among ECD. 53% of kidneys were rejected after zero-time KB analysis; there was no difference in individual clinical and biological data between accepted/rejected groups. However, histology of rejected kidneys showed more sclerotic glomeruli (20% vs. 8%; P < 0.001), increased interstitial fibrosis (1.25 ± 0.12 vs. 0.47 ± 0.09; P < 0.0001), more arteriosclerosis (2.14 ± 0.17 vs. 1.71 ± 0.11; P = 0.0032) and arteriolar hyalinosis (2.15 ± 0.12 vs. 1.55 ± 0.11; P = 0.0006). Using propensity score matching, we generated a group of 42 kidney allograft recipients who received a transplant matched for donor zero-time histology and clinical characteristics with donors whose kidneys were rejected. Interestingly, their 1- and 5-year graft survival and function were similar to the global cohort of ECD recipients. In conclusion, when performed, zero-time KB was a decisive element for kidney discard decision. However, adverse zero-time histology was not associated with poorer graft survival and kidney function among ECD.

A review of kidney transplantation from HCV-viremic donors into HCV-negative recipients

The safety and efficacy of direct-acting antiviral therapies have allowed the transplantation of organs from hepatitis C virus (HCV)-viremic donors into uninfected recipients. This novel strategy contrasts with the previous standard-of-care practice of limiting the transplantation of HCV infected-donor organs to HCV-infected recipients, or all too often, discarding viable organs. In this review, we summarize the published literature about the safety and feasibility of transplanting organs from HCV-viremic donors, the challenges that hinder wider adoption of this strategy, and future research needs.

Highly Sensitized Patients Are Well Served by Receiving a Compatible Organ Offer Based on Acceptable Mismatches

Highly sensitized kidney patients accrue on the transplant waiting list due to their broad immunization against non-self Human Leucocyte Antigens (HLA). Although challenging, the best option for highly sensitized patients is transplantation with a crossmatch negative donor without any additional therapeutic intervention. The Eurotransplant Acceptable Mismatch (AM) program was initiated more than 30 years ago with the intention to increase the chance for highly sensitized patients to be transplanted with such a compatible donor. The AM program allows for enhanced transplantation to this difficult to transplant patient group by allocating deceased donor kidneys on the basis of a match with the recipient’s own HLA antigens in combination with predefined acceptable antigens. Acceptable antigens are those HLA antigens towards which the patients has never formed antibodies, as determined by extensive laboratory testing. By using this extended HLA phenotype for allocation and giving priority whenever a compatible donor organ becomes available, organ offers are made for roughly 80% of patients in this program. Up till now, more than 1700 highly sensitized patients have been transplanted through the AM program. Recent studies have shown that the concept of acceptable mismatches being truly immunologically acceptable holds true for both rejection rates and long-term graft survival. Patients that were transplanted through the AM program had a similar rejection incidence and long-term graft survival rates identical to non-sensitized patients transplanted through regular allocation. However, a subset of patients included in the AM program does not receive an organ offer within a reasonable time frame. As these are often patients with a rare HLA phenotype in comparison to the Eurotransplant donor population, extension of the donor pool for these specific patients through further European collaboration would significantly increase their chances of being transplanted. For those patients that will not benefit from such strategy, desensitization is the ultimate solution.

The Introduction of cPRA and Its Impact on Access to Deceased Donor Kidney Transplantation for Highly Sensitized Patients in Australia

BACKGROUND

In March 2016, Australia's deceased donor kidney allocation program introduced calculated panel reactive antibody (cPRA) based on antibody exclusions using multiplex assays to define sensitization for waitlisted candidates. We aimed to assess the impact of this change and review access to transplantation for highly sensitized patients under the current allocation rules.

METHODS

Registry data were used to reconstruct changes in panel reactive antibody (PRA)/cPRA for all patients active on the waiting list between 2013 and 2018. A multilevel, mixed-effects negative binomial regression model was used to determine the association between sensitization and transplantation rate in the cPRA era.

RESULTS

Following the introduction of cPRA, there was an increase in the percentage of the waiting list classified as highly sensitized (PRA/cPRA ≥80%) from 7.2% to 27.8% and very highly sensitized (PRA/cPRA ≥99%) from 2.7% to 15.3%. Any degree of sensitization was associated with a decreased rate of transplantation with a marked reduction for those with cPRA 95%-98% (adjusted incidence rate ratio, 0.36 [95% confidence interval, 0.28-0.47], P < 0.001) and cPRA ≥99% (adjusted incidence rate ratio, 0.09 [95% confidence interval, 0.07-0.12], P < 0.001).

CONCLUSIONS

The proportion of the waiting list classified as highly sensitized increased substantially following the introduction of cPRA, and despite current prioritization, very highly sensitized patients have markedly reduced access to deceased donor transplantation.

Greater complexity and monitoring of the new Kidney Allocation System: Implications and unintended consequences of concentric circle kidney allocation on network complexity

The deceased donor kidney allocation system in the United States has undergone several rounds of iterative changes, but these changes were not explicitly designed to address the geographic variation in access to transplantation. The new allocation system, expected to start in December 2020, changes the definition of "local allocation" from the Donation Service Area to 250 nautical mile circles originating from the donor hospital. While other solid organs have adopted a similar approach, the larger number of both kidney transplant centers and transplant candidates is likely to have different consequences. Here, we discuss the incredible increase in complexity in allocation, discuss some of the likely intended and unintended consequences, and propose metrics to monitor the new system.

Accuracy of the Sequential Organ Failure Assessment Score for In-Hospital Mortality by Race and Relevance to Crisis Standards of Care

IMPORTANCE

Crisis Standards of Care (CSC) are guidelines for rationing health care resources during public health emergencies. The CSC adopted by US states ration intensive care unit (ICU) admission using the Sequential Organ Failure Assessment (SOFA) score, which is used to compare expected in-hospital mortality among eligible patients. However, it is unknown if Black and White patients with equivalent SOFA scores have equivalent in-hospital mortality.

OBJECTIVE

To investigate whether reliance on SOFA is associated with bias against Black patients in CSC.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted using data from the eICU Collaborative Research Database of patients admitted to 233 US ICUs in 2014 to 2015. Included individuals were Black and White adult patients in the ICU, who were followed up to hospital discharge. Data were analyzed from May 2020 through April 2021.

EXPOSURE

SOFA scores at ICU admission.

MAIN OUTCOMES AND MEASURES

Hierarchical logistic regression with hospital fixed effects was used to measure the interaction between race and SOFA as a factor associated with in-hospital mortality, as well as the odds of death among Black and White patients with equivalent priority for resource allocation according to the SOFA-based ranking rules of 3 statewide CSC (denoted A, B, and C) under shortage conditions that were severe (ie, only patients with the highest priority would be eligible for allocation), intermediate (ie, patients in the highest 2 tiers would be eligible for allocation), or low (ie, only patients with the lowest priority would be at risk of exclusion).

RESULTS

Among 111 885 ICU encounters representing 95 549 patients, there were 16 688 encounters with Black patients (14.9%) and 51 464 (46.0%) encounters with women and the mean (SD) age was 63.3 (16.9) years. The median (interquartile range) SOFA score was not statistically significantly different between Black and White patients (4 [2-6] for both groups; P = .19), but mortality was lower among Black individuals compared with White individuals with equivalent SOFA scores (odds ratio [OR], 0.98; 95% CI, 0.97-0.99; P < .001). This was associated with lower mortality among Black patients compared with White patients prioritized for resource allocation in 3 CSC under shortage conditions that were severe (system A: OR, 0.65; 95% CI, 0.58-0.74; P < .001; system B: OR, 0.70; 95% CI, 0.64-0.78; P < .001; system C: OR, 0.73; 95% CI, 0.67-0.80; P < .001), intermediate (system A: OR, 0.73; 95% CI, 0.67-0.80; P < .001; system B: OR, 0.83; 95% CI, 0.77-0.89; P < .001; system C: OR, 0.82; 95% CI, 0.77-0.89; P < .001), and low (system A: OR, 0.83; 95% CI, 0.77-0.89; P < .001; system C: OR, 0.86; 95% CI, 0.81-0.92; P < .001; not applicable for system B, which had fewer tiers). When SOFA-based ranking rules were adjusted for Black patients to simulate equitable allocation based on observed mortality, the proportion upgraded to higher priority ranged from 379 Black patient encounters (2.3%) in low shortage conditions to 2601 Black patient encounters (15.6%) in severe shortage conditions.

CONCLUSIONS AND RELEVANCE

This study found that SOFA scores were associated with overestimated mortality among Black patients compared with White patients, and this was associated with a structural disadvantage for Black patients in CSC allocation systems. These findings suggest that guidelines should be revised to correct this inequity and alternative methods should be developed for more equitable triage.

Predicting Kidney Transplant Survival using Multiple Feature Representations for HLAs

Kidney transplantation can significantly enhance living standards for people suffering from end-stage renal disease. A significant factor that affects graft survival time (the time until the transplant fails and the patient requires another transplant) for kidney transplantation is the compatibility of the Human Leukocyte Antigens (HLAs) between the donor and recipient. In this paper, we propose new biologically-relevant feature representations for incorporating HLA information into machine learning-based survival analysis algorithms. We evaluate our proposed HLA feature representations on a database of over 100,000 transplants and find that they improve prediction accuracy by about 1%, modest at the patient level but potentially significant at a societal level. Accurate prediction of survival times can improve transplant survival outcomes, enabling better allocation of donors to recipients and reducing the number of re-transplants due to graft failure with poorly matched donors.

The impact of multi-organ transplant allocation priority on waitlisted kidney transplant candidates

Kidney-alone transplant (KAT) candidates may be disadvantaged by the allocation priority given to multi-organ transplant (MOT) candidates. This study identified potential KAT candidates not receiving a given kidney offer due to its allocation for MOT. Using the Organ Procurement and Transplant Network (OPTN) database, we identified deceased donors from 2002 to 2017 who had one kidney allocated for MOT and the other kidney allocated for KAT or simultaneous pancreas-kidney transplant (SPK) (n = 7,378). Potential transplant recipient data were used to identify the "next-sequential KAT candidate" who would have received a given kidney offer had it not been allocated to a higher prioritized MOT candidate. In this analysis, next-sequential KAT candidates were younger (p < .001), more likely to be racial/ethnic minorities (p < .001), and more highly sensitized than MOT recipients (p < .001). A total of 2,113 (28.6%) next-sequential KAT candidates subsequently either died or were removed from the waiting list without receiving a transplant. In a multivariable model, despite adjacent position on the kidney match-run, mortality risk was significantly higher for next-sequential KAT candidates compared to KAT/SPK recipients (hazard ratio 1.55, 95% confidence interval 1.44, 1.66). These results highlight implications of MOT allocation prioritization, and potential consequences to KAT candidates prioritized below MOT candidates.

In Search of a Better Outcome: Opting Into the Live Donor Paired Kidney Exchange Program

Background

Live donor (LD) kidney transplantation is the best option for patients with end-stage kidney disease (ESKD). However, this may not be the best option if a patient's donor is older and considerably smaller in weight. Patient (A) with a less than ideal donor (Donor A) might enter into a live donor paired exchange (LDPE) program with the hopes of swapping for a better-quality organ. A second patient (B) who is in the LDPE may or may not benefit from this exchange with Donor A.

Methods

This medical decision analysis examines the conditions that favor Patient A entering into the LDPE compared to directly accepting a kidney from their intended donor, as well as the circumstances where Patient B also benefits by accepting a lower-quality organ.

Results

Under select circumstances, a paired exchange could benefit both Patients A and B. For example, a 30-year-old Patient A with a lower-quality donor might gain _1.201.52_1.84 quality adjusted life years (QALYs) by entering into a LDPE for a better-quality kidney, whereas a 60-year-old Patient B might gain _0.931.03_1.13 QALYs by accepting Donor A's kidney rather than waiting longer in the LDPE. The net benefit (or loss) of entering the LDPE differs by recipient age, donor organ quality, likelihood of Patient B being transplanted in LDPE, and likelihood of Patient A finding an ideal donor in the LDPE.

Conclusion

This study shows there are ways to increase live donor utilization and effectiveness that require further research and potentially changes to the LDPE process.

Measuring human leukocyte antigen alloantibodies: beyond a binary decision

PURPOSE OF REVIEW

Accurate measurement of human leukocyte antigen antibodies is critical for making clinical decisions treating patients awaiting transplantation or monitoring them post transplantation. Single antigen bead assay results are given as Mean Fluorescence Intensity, falling short of providing the required quantitative measure.

RECENT FINDINGS

Titration studies were shown to circumvent the limitation of target-saturation that affect interpretation of single antigen bead assays especially in highly sensitized patients with strong antibodies. In fact, titration information can serve to measure efficacy of antibody removal during pretransplant desensitization using plasmapheresis/intravenous immunoglobulin (PP/IVIg) approaches. Moreover, recent studies indicate that knowing the donor-specific antibody titer has prognostic value that can guide PP/IVIg desensitization treatments. Newer data demonstrates an additional layer of information obtained by titration studies allowing to stratify patients with very high cPRA (>99%) based on the strength of the antibodies present, rather than the breadth. This data can thereby identify patients that are more likely to benefit from desensitization approaches on the transplant wait-list.

SUMMARY

Titration studies have a prognostic value with regards to quantifying antibody strength. Obtaining this information does not require performing the complete set of dilutions. In fact, performing two to three specific dilutions can provide relevant information while maintaining practical cost.

Impact of deceased donor with acute kidney injury on subsequent kidney transplant outcomes-an ANZDATA registry analysis

BACKGROUND

The need for kidney transplantation drives efforts to expand organ donation. The decision to accept organs from donors with acute kidney injury (AKI) can result in a clinical dilemma in the context of conflicting reports from published literature.

MATERIAL AND METHODS

This observational study included all deceased donor kidney transplants performed in Australia and New Zealand between 1997 and 2017. The association of donor-AKI, defined according to KDIGO criteria, with all-cause graft failure was evaluated by multivariable Cox regression. Secondary outcomes included death-censored graft failure, death, delayed graft function (DGF) and acute rejection.

RESULTS

The study included 10,101 recipients of kidneys from 5,774 deceased donors, of whom 1182 (12%) recipients received kidneys from 662 (11%) donors with AKI. There were 3,259 (32%) all-cause graft failures, which included 1,509 deaths with functioning graft. After adjustment for donor, recipient and transplant characteristics, donor AKI was not associated with all-cause graft failure (adjusted hazard ratio [HR] 1.11, 95% CI 0.99-1.26), death-censored graft failure (HR 1.09, 95% CI 0.92-1.28), death (HR 1.15, 95% CI 0.98-1.35) or graft failure when death was evaluated as a competing event (sub-distribution hazard ratio [sHR] 1.07, 95% CI 0.91-1.26). Donor AKI was not associated with acute rejection but was associated with DGF (adjusted odds ratio [OR] 2.27, 95% CI 1.92-2.68).

CONCLUSION

Donor AKI stage was not associated with any kidney transplant outcome, except DGF. Use of kidneys with AKI for transplantation appears to be justified.

Outcome of kidney transplantation from very senior donors in Switzerland - a national cohort study

Kidney transplantation from older and marginal donors is effective to confront organ shortage. However, limitations after transplantation of kidneys from very marginal kidney donors remain unclear. We compared patient and graft outcome, achieved allograft function and quality of life of renal transplantations from Very Senior Donors (VSD, defined as donors aged 70 years and older) with Senior Donors (SD, aged 60-70 years) and Regular Donors (RD, aged younger than 60 years) in Switzerland. We evaluated the outcome of 1554 adult recipients of deceased donor kidney transplantations from 05/2008 to 12/2019; median follow-up was 4.7 years. Failure-free survival (freedom from graft loss or death), glomerular filtration rate (eGFR), and quality of life at 12 months were analyzed for RD (reference group, n = 940), SD (n = 404), and VSD (n = 210). Failure-free survival decreased with increasing donor age, mainly attributable to premature graft loss. Still, overall 5-year failure-free survival reached 83.1%, 81.0%, and 64.0% in the RD, SD, and VSD subgroups, respectively. eGFR 12 months post-transplantation was significantly higher in RD compared with SD and VSD. The acceptance rate of donor candidates for kidney TPL was 78% for the entire cohort (87% for RD, 79% for SD, and 56% for VSD). Deceased donor kidney transplantation from donors aged 70 years or older is associated with an inferior, yet acceptable failure-free outcome, with sustained quality of life.

Covariates adjustment questioned conclusions of predictive analyses: an illustration with the Kidney Donor Risk Index

OBJECTIVES

We aimed to illustrate that considering covariates can lead to meaningful interpretation of the discriminative capacities of a prognostic marker. For this, we evaluated the ability of the Kidney Donor Risk Index (KDRI) to discriminate kidney graft failure risk.

STUDY DESIGN AND SETTING

From 4114 French patients, we estimated the adjusted area under the time-dependent ROC curve by standardizing the marker and weighting the observations. By weighting the contributions, we also studied the impact of KDRI-based transplantations on the patient and graft survival.

RESULTS

The covariate-adjusted AUC varied from 55% (95% confidence interval [CI]: 51-60%) for a prognostic up to 1 year post-transplantation to 56% (95% CI: 52-59%) up to 7 years. The Restricted Mean Survival Time (RMST) was 6.44 years for high-quality graft recipients (95% CI: 6.30-6.56) and would have been 6.31 years (95% CI: 6.13-6.46) if they had medium-quality transplants. The RMST was 5.10 years for low-quality graft recipients (95% CI: 4.90-5.31) and would have been 5.52 years (95% CI: 5.17-5.83) if they had medium-quality transplants.

CONCLUSION

We demonstrated that the KDRI discriminative capacities were mainly explained by the recipient characteristics. We also showed that counterfactual estimations, often used in causal studies, are also interesting in predictive studies, especially regarding the new available methods.

The Advantage of Multiple Listing Continues in the Kidney Allocation System Era

BACKGROUND

Transplant candidates can be listed at multiple transplant centers to increase the probability of receiving an organ. We evaluated the association between multilisting (ML) status and access to a deceased donor kidney transplant (DDKT) to determine if ML provides a long-term advantage regarding wait-list mortality and recipient outcomes.

MATERIALS AND METHODS

Candidates between January 2010 and October 2017 were identified as either singly or multiply listed using Organ Procurement and Transplantation Network data and cohorts before and after implementation of the Kidney Allocation System (KAS). Cross-sectional logistic regression was used to assess relationships between candidate factors and ML prevalence (5.4%).

RESULTS

Factors associated with ML pre-KAS included having blood type B (reference, type O; odds ratio [OR], 1.20; P < .001), having private insurance (OR, 1.5; P < .001), wait time (OR, 1.28; P < .001), and increasing calculated panel-reactive antibody (cPRA) (reference, cPRA 0-100; OR for cPRA 80-98, 2.83; OR for cPRA 99, 3.47; OR for cPRA 100, 5.18; P < .001). Transplant rates were double for multilisted vs singly listed recipients (adjusted hazard ratio [aHR], 2.16; P < .001). Extra-donor service area ML candidates received transplants 2.5 years quicker than single-listing (SL) candidates, conferring a 42% wait-list advantage. Recipient death (aHR, 0.94; P = .122) and graft failure (aHR, 0.91; P = .006) rates were also lower for ML recipients.

CONCLUSIONS

In the KAS era, ML continues to increase the likelihood of receiving a DDKT and lower the incidence of wait-list mortality, and it confers a survival advantages over SL.