Kidney Allocation System Research Articles

Rescue Allocation Modes in Eurotransplant Kidney Transplantation: Recipient Oriented Extended Allocation Versus Competitive Rescue Allocation-A Retrospective Multicenter Outcome Analysis.

Whenever the kidney standard allocation (SA) algorithms according to the Eurotransplant (ET) Kidney Allocation System or the Eurotransplant Senior Program fail, rescue allocation (RA) is initiated. There are 2 procedurally different modes of RA: recipient oriented extended allocation (REAL) and competitive rescue allocation (CRA). The objective of this study was to evaluate the association of patient survival and graft failure with RA mode and whether or not it varied across the different ET countries. The ET database was retrospectively analyzed for donor and recipient clinical and demographic characteristics in association with graft outcomes of deceased donor renal transplantation (DDRT) across all ET countries and centers from 2014 to 2021 using Cox proportional hazards methods. Seventeen thousand six hundred seventy-nine renal transplantations were included (SA 15 658 [89%], REAL 860 [4.9%], and CRA 1161 [6.6%]). In CRA, donors were older, cold ischemia times were longer, and HLA matches were worse in comparison with REAL and especially SA. Multivariable analyses showed comparable graft and recipient survival between SA and REAL; however, CRA was associated with shorter graft survival. Germany performed 76% of all DDRTs after REAL and CRA and the latter mode reduced waiting times by up to 2.9 y. REAL and CRA are used differently in the ET countries according to national donor rates. Both RA schemes optimize graft utilization, lead to acceptable outcomes, and help to stabilize national DDRT programs, especially in Germany.

Radical Transparency to Improve Equity in the Kidney Allocation System.

Radical Transparency to Improve Equity in the Kidney Allocation System.

Increasing Access to Kidney Transplantation for Black and Asian Patients Through Modification of the Current A2 to B Allocation Policy.

The rate of A2 to B incompatible (ABO-i) kidney transplant continues to be low despite measures in the new Kidney Allocation System (KAS) to facilitate such transplants. This paper shows how the number of ABO-i transplants could increase if KAS policies were utilized to their fullest extent through a boost in ABO-i priority points. Predicting transplant outcomes using the Kidney Pancreas Simulated Allocation Model (KPSAM), preloaded with national data of 2010. We used this simulation to compare KAS to a new intervention in which priority equal to cPRA=100 has been given to blood type B candidate who are willing to accept an A blood type organ. The number of African American recipients increased by 375 (from 35% of recipient population to 38.7%), the number of blood type B African Americans increased by 65 (from 8% of recipient population to 9%), and the number of blood type B African Americans receiving blood type A kidneys increased by 49 (from 2% of recipient population to 2.5%). The same change occurred for Asians, particularly blood type B Asians (from 0.54% of the recipient population to 0.7%). Average wait time notably decreased by 27 days for blood type B African Americans. In the proposed scenario, 263 blood type B African Americans received blood type A organ (2.5% of recipient population) while only 181 (1.1%) of such transplants were performed in 2021. These results signify a considerable opportunity loss of ABO-i transplants for African American patients. If this policy was universally adopted, we would expect to see an overall increase of A2 to B transplantation, but in reality, not all centers perform ABOi transplantation. Thus, adopting this policy would incentivize other centers to perform more subtyping of A-type kidneys, and it would increase access to organs for blood type B Asian and African Americans in centers where ABOi transplantation already takes place.

Approaches to Mitigate Longer Cold Ischemic Times and Increased Rates of Delayed Graft Function Associated With the Revised Kidney Allocation System

Approaches to Mitigate Longer Cold Ischemic Times and Increased Rates of Delayed Graft Function Associated With the Revised Kidney Allocation System

Effect of Kidney Allocation System (KAS) Policy on Renal Transplantation in Elderly Recipients

Effect of Kidney Allocation System (KAS) Policy on Renal Transplantation in Elderly Recipients

Knowledge About Renal Transplantation Among African, Caribbean, and Black Canadian Patients With Advanced Kidney Failure

Variable transplant-related knowledge may contribute to inequitable access to living donor kidney transplant (LDKT). We compared transplant-related knowledge between African, Caribbean, and Black (ACB) versus White Canadian patients with kidney failure using the Knowledge Assessment of Renal Transplantation (KART) questionnaire. This was a cross-sectional cohort study. Data were collected from a cross-sectional convenience sample of adults with kidney failure in Toronto. Participants also answered an exploratory question about their distrust in the kidney allocation system. Clinical characteristics were abstracted from medical records. The potential contribution of distrust to differences in transplant knowledge was assessed in mediation analysis. Among 577 participants (mean [SD] age 57 [14] years, 63% male), 25% were ACB, and 43% were White Canadians. 45% of ACB versus 26% of White participants scored in the lowest tertile of the KART score. The relative risk ratio to be in the lowest tertile for ACB compared to White participants was 2.22 (95% confidence interval [CI]: 1.11, 4.43) after multivariable adjustment. About half of the difference in the knowledge score between ACB versus White patients was mediated by distrust in the kidney allocation system. Participants with kidney failure from ACB communities have less transplant-related knowledge compared to White participants. Distrust is potentially contributing to this difference.

Continuous allocation: The problem with EPTS and pediatric kidney candidates.

The 2014 Kidney Allocation System (KAS) introduced longevity matching for adult candidates using the Estimated Post-Transplant Survival (EPTS) score, which includes candidate age, time on dialysis, diabetes status, and number of previous solid organ transplants. The proposed continuous distribution framework may expand the use of this attribute to pediatric candidates, but there is no data on its performance among pediatric kidney transplant recipients. We performed a retrospective cohort study of 6800 pediatric kidney transplant recipients from 2001 to 2011 using Organ Procurement and Transplantation Network (OPTN) data. EPTS score was calculated for each patient and compared to reported patient survival to estimate the validity of the score in children. The median age of patients was 14.01 years (IQR 9.29-16.37 years), and dialysis vintage was 0.67 years (IQR 0-1.82 years). 18.2% of the cohort had a prior transplant and 1% had diabetes. Median EPTS score was 2 (IQR 1-2). Seven percent of patients died during the study period and 54.7% of the cohort was censored prior to 10 years. The c-statistic was 0.505 (95% CI: 0.49-0.53). Overall, EPTS is not a valid predictor of patient survival among pediatric kidney transplant recipients.

Equity matrix for kidney transplant allocation

There is a general agreement that the distribution of kidneys for transplantation should balance utility criteria with justice. Moreover, a kidney allocation system must be based on transparent policies and seen as an ongoing process.This study aims to present an allocation system grounded on an equity matrix that balances the criteria of utility and justice.Synthetic data for a waiting list with 2000 transplant candidates and a pool of 280 donors were generated. A color priority system, the Eurotransplant (ET) kidney allocation system, and the proposed Equity Matrix (EQM) allocation system were compared after 1000 iterations of kidney allocations. Distributions of variables like the age difference, Human Leukocyte Antigens (HLA) mismatches (mmHLA), recipients' time on dialysis, cPRA, and a transplant score obtained by different allocation models were compared graphically and with Cohen's d effect size.For the analyzed variables, when we compare only the selected recipients from ET with the selected recipients from the EQM neutral model, we can conclude that the former model selects more hypersensitized recipients, a higher number of 65+ years' old recipients with 65+ years' old donors and higher number of recipients with 0 mmHLA. While recipients from EQM neutral are slightly older, have a lower age difference with their donors, have a lower number of mmHLA, are less likely to have 6 mmHLA with their donors, and have more time on dialysis.The proposed EQM model attempts to provide a simple, transparent, and equitable response to a complex question with results that outperform established practices.

Race, Age, and Kidney Transplant Waitlisting Among Patients Receiving Incident Dialysis in the United States

Patients with kidney failure from racial and ethnic minority groups and older patients have reduced access to the transplant waitlist relative to White and younger patients. Although racial disparities in the waitlisting group have declined after the 2014 kidney allocation system change, whether there is intersectionality of race and age in waitlisting access is unknown. Retrospective cohort study. 439,455 non-Hispanic White and non-Hispanic Black US adults initiating dialysis between 2015 and 2019 were identified from the United States Renal Data System, and followed through2020. Patient race and ethnicity (non-Hispanic White and non-Hispanic Black) and age group (18-29, 30-49, 50-64, and 65-80 years). Placement on the United Network for Organ Sharing deceased donor waitlist. Age- and race-stratified waitlisting rates were compared. Multivariable Cox proportional hazards models, censored for death, examined the association between race and waitlisting, and included interaction term for race and age. Over a median follow-up period of 1 year, the proportion of non-Hispanic White and non-Hispanic Black patients waitlisted was 20.7% and 20.5%, respectively. In multivariable models, non-Hispanic Black patients were 14% less likely to be waitlisted (aHR, 0.86, 95% CI, 0.77-0.95). Relative differences between non-Hispanic Black and non-Hispanic White patients were different by age group. Non-Hispanic Black patients were 27%, 12%, and 20% less likely to be waitlisted than non-Hispanic White patients for ages 18-29 years (aHR, 0.73; 95% CI, 0.61-0.86), 50-64 (aHR, 0.88; 95% CI, 0.80-0.98), and 65-80 years (aHR, 0.80; 95% CI, 0.71-0.90), respectively, but differences were attenuated among patients aged 30-49 years (aHR, 0.89; 95% CI, 0.77-1.02). Race and ethnicity data is physician reported, residual confounding, and analysis is limited to non-Hispanic White and non-Hispanic Black patients. Racial disparities in waitlisting exist between non-Hispanic Black and non-Hispanic White individuals and are most pronounced among younger patients with kidney failure. Results suggest that interventions to address inequalities in waitlisting may need to be targeted to younger patients with kidney failure. Research has shown that patients from racial and ethnic minority groups and older patients have reduced access to transplant waitlisting relative to White and younger patients; nevertheless, how age impacts racial disparities in waitlisting is unknown. We compared waitlisting between non-Hispanic Black and non-Hispanic White patients with incident kidney failure, within age strata, using registry data for 439,455 US adults starting dialysis (18-80 years) during 2015-2019. Overall, non-Hispanic Black patients were less likely to be waitlisted and relative differences between the two racial groups differed by age. After adjusting for patient-level factors, the largest disparity in waitlisting was observed among adults aged 18-29 years. These results suggest that interventions should target younger adults to reduce disparities in access to kidney transplant waitlisting.

Regional Differences in Waiting Times Before Kidney Transplantation in Germany.

In order to achieve short ischemia times between organ donation and transplantation, regional organ allocation has been assigned priority in the development of allocation rules for kidney transplantation. It is unclear whether this leads to differences in regional waiting times in Germany. A retrospective cohort study over a 24-month observation period was conducted, including all patients who received a kidney-only graft allocated via the standard Eurotransplant Kidney Allocation System (ETKAS) (n = 1487) or the Eurotransplant Senior Program (ESP) (n = 566). Multiple linear regression analyses were performed to investigate differences in waiting times across the regions (ETKAS) or subregions (ESP) as defined by the German Organ Procurement Organization (DSO). Associations between the number of regionally procured kidneys (n = 1444) and regional waiting times were investigated. In ETKAS, the median waiting time was 8.9 years (interquartile range [IQR] 6.7-10.6); in ESP, it was 3.9 (2.4 -5.3) years. Compared with the reference region with the shortest waiting time, waiting times in other regions were 0.6 to 1.7 years longer in ETKAS and 1.3 to 4.4 years longer in ESP. The ratio of the number of patients on the waiting list for a particular region to the number of organs donated in that region was associated with the waiting time in ETKAS (R2 = 0.70). In ESP, this association was markedly less pronounced (R2 = 0.45). In Germany, waiting times depend strongly on the region where a patient is listed for kidney transplantation, especially in ESP. These findings call the current allocation algorithms into question and imply a need for suitable modification.

Immunized Patients Face Reduced Access to Transplantation in the Eurotransplant Kidney Allocation System.

The presence of donor-specific HLA antibodies before transplantation is associated with poor transplantation outcomes. Unacceptable antigens can be assigned for Eurotransplant kidney transplant candidates to prevent kidney offers against which the candidate has developed clinically relevant HLA antibodies. This retrospective cohort study aimed to assess to what degree unacceptable antigens affect access to transplantation in the Eurotransplant Kidney Allocation System (ETKAS). Candidates who underwent kidney-only transplantation between 2016 and 2020 were included (n = 19 240). Cox regression was used to quantify the relationship between the relative transplantation rate and virtual panel-reactive antibodies (vPRAs), which is the percentage of the donor pool with unacceptable antigens. Models used accrued dialysis time as the timescale; were stratified by country and blood group of patient and were adjusted for nontransplantable status, patient age, sex, history of kidney transplantations, and prevalence of 0 HLA-DR-mismatched donors. Transplantation rates were 23% lower for vPRA 0.1% to 50%, 51% lower for vPRA 75% to 85%, and decreased rapidly for vPRA of >85%. Prior studies showed significantly lower ETKAS transplantation rates only for highly sensitized patients (vPRA of >85%). The inverse relationship between transplantation rate and vPRA is independent of Eurotransplant country, listing time, and 0 HLA-DR-mismatched donor availability. Results were similar when quantifying the relationship between vPRA and attainment of a sufficiently high rank for an ETKAS offer, suggesting lower transplantation rates for immunized patients are due to current ETKAS allocation. Immunized patients face lower transplantation rates across Eurotransplant. The current ETKAS allocation mechanism inadequately compensates immunized patients for reduced access to transplantation.

Increased volume of organ offers and decreased efficiency of kidney placement under circle-based kidney allocation

The newest kidney allocation policy kidney allocation system 250 (KAS250) broadened geographic distribution while increasing allocation system complexity. We studied the volume of kidney offers received by transplant centers and the efficiency of kidney placement since KAS250. We identified deceased-donor kidney offers (N = 907,848; N = 36,226 donors) to 185 US transplant centers from January 1, 2019, to December 31, 2021 (policy implemented March 15, 2021). Each unique donor offered to a center was considered a single offer. We compared the monthly volume of offers received by centers and the number of centers offered before the first acceptance using an interrupted time series approach (pre-/post-KAS250). Post-KAS250, transplant centers received more kidney offers (level change: 32.5 offers/center/mo, P < .001; slope change: 3.9 offers/center/mo, P = .003). The median monthly offer volume post-/pre-KAS250 was 195 (interquartile range 137-253) vs. 115 (76-151). There was no significant increase in deceased-donor transplant volume at the center level after KAS250, and center-specific changes in offer volume did not correlate with changes in transplant volume (r = −0.001). Post-KAS250, the number of centers to whom a kidney was offered before acceptance increased significantly (level change: 1.7 centers/donor, P < .001; slope change: 0.1 centers/donor/mo, P = .014). These findings demonstrate the logistical burden of broader organ sharing, and future allocation policy changes will need to balance equity in transplant access with the operational efficiency of the allocation system.

Deceased Donor Kidney Transplantation for Older Transplant Candidates: A New Microsimulation Model for Determining Risks and Benefits.

Under the current US kidney allocation system, older candidates receive a disproportionately small share of deceased donor kidneys despite a reserve of potentially usable kidneys that could shorten their wait times. To consider potential health gains from increasing access to kidneys for these candidates, we developed and calibrated a microsimulation model of the transplantation process and long-term outcomes for older deceased donor kidney transplant candidates. We estimated risk equations for transplant outcomes using the Scientific Registry of Transplant Recipients (SRTR), which contains data on all US transplants (2010-2019). A microsimulation model combined these equations to account for competing events. We calibrated the model to key transplant outcomes and used acceptance sampling, retaining the best-fitting 100 parameter sets. We then examined life expectancy gains from allocating kidneys even of lower quality across patient subgroups defined by age and designated race/ethnicity. The best-fitting 100 parameter sets (among 4,000,000 sampled) enabled our model to closely match key transplant outcomes. The model demonstrated clear survival benefits for those who receive a deceased donor kidney, even a lower quality one, compared with remaining on the waitlist where there is a risk of removal. The expected gain in survival from receiving a lower quality donor kidney was consistent gains across age and race/ethnic subgroups. Limited available data on socioeconomic factors. Our microsimulation model accurately replicates a range of key kidney transplant outcomes among older candidates and demonstrates that older candidates may derive substantial benefits from transplantation with lower quality kidneys. This model can be used to evaluate policies that have been proposed to address concerns that the current system disincentivizes deceased donor transplants for older patients. The microsimulation model was consistent with the data after calibration and accurately simulated the transplantation process for older deceased donor kidney transplant candidates.There are clear survival benefits for older transplant candidates who receive deceased donor kidneys, even lower quality ones, compared with remaining on the waitlist.This model can be used to evaluate policies aimed at increasing transplantation among older candidates.

The real unmet need: A multifactorial approach for identifying sensitized kidney candidates with low access to transplant.

At the start of 2020, the kidney waiting list consisted of 2526 candidates with a calculated panel reactive antibody (CPRA) of 99.9% or greater, a cohort demonstrated in published research to have meaningfully lower than average access to transplantation even under the revised kidney allocation system (KAS). This was a retrospective analysis of US kidney registrations using data from the OPTN [Reference (https://optn.transplant.hrsa.gov/data/about-data/)]. The period-prevalent study cohort consisted of US kidney-alone registrations who waited at least 1 day between April 1, 2016, when HLA DQ-Alpha and DP-Beta unacceptable antigen data became available in OPTN data collection, to December 31, 2019. Poisson rate regression was used to model deceased donor kidney transplant rates per active year waiting and using an offset term to account for differential at-risk periods. Median time to transplant was estimated for each IRR group using the Kaplan-Meier method. Sensitivity analyses were included to address geographic variation in supply-to-demand ratios and differences in dialysis time or waiting time. In this study, we found 1597 additional sensitized (CPRA 50-<99.9%) candidates with meaningfully lower than average access to transplant when simultaneously taking into account CPRA and other factors. In combination with CPRA, candidate blood type, Estimated Post-Transplant Survival Score (EPTS), and presence of other antibody specificities beyond those in the current, 5-locus CPRA were found to influence the likelihood of transplant. In total, this suggests approximately 4100 sensitized candidates are on the waiting list who represent a community of disadvantaged patients who may benefit from progressive therapies and interventions to facilitate incompatible transplantation. Though associated with higher risks, such interventions may nevertheless be more attractive than remaining on dialysis with the associated accumulation of mortality risk over time.

March 2021 New Kidney Allocation: How Did the New Changes Affect the Deceased Donor Kidney Transplant Outcomes?

Given the shortage of kidney donations relative to the ever-increasing demand, there is an ongoing need to utilize available donor organs efficiently and fairly. The purpose of the deceased donor Kidney Allocation System is to optimize and equalize organ access for candidates nationwide. We investigated the outcomes of kidney transplant cases before and after the new allocation placement in March 2021 and the effect of the new allocation system on these outcomes. We retrospectively reviewed the medical records of the recipients. Outcomes in recipients of renal allografts were compared before and after the changes in March 2021 to the Kidney Allocation System. There were 333 (73.7%) renal allografts transplanted before the 2021 new allocation, and 119 (26.3%) recipients received their renal allografts after the new allocation. The rate of delayed graft function was 33.3% in the preallocation group and 38.65% in the postallocation group (P = .29). The rate for patient readmission within 30 days was compared between the groups and did not show a statistically significant difference (37.8% vs 39.5%; P = .75). The 1-year graft survival rate was 97.5% in the postallocation group and 95.5% in the preallocation group (P = .526). The 1-year patient survival rate was 98.3% in the postallocation group and 95.8% in the preallocation group (P = .499). This study provides reassurance in finding no statistically significant differences between patient outcomes before and after the implementation of the March 2021 change to the Kidney Allocation System. However, the new allocation measures would help for a more equal distribution of the kidneys.

Increasing Discards as an Unintended Consequence of Recent Changes in United States Kidney Allocation Policy

Kidney transplantation is the preferred treatment for end-stage kidney disease.1Wolfe RA Ashby VB Milford EL et al.Comparison of mortality in all patients on dialysis, patients on dialysis awaiting transplantation, and recipients of a first cadaveric transplant.N Engl J Med. 1999; 341: 1725-1730Crossref PubMed Scopus (3958) Google Scholar Despite a shortage of donated kidneys, the United States has the highest proportion of deceased donor kidneys (DDKs) recovered for transplant that are subsequently discarded, resulting in federal government prioritization of improving organ utilization.2Aubert O Reese PP Audry B et al.Disparities in Acceptance of Deceased Donor Kidneys Between the United States and France and Estimated Effects of Increased US Acceptance.JAMA Intern Med. 2019; 179: 1365-1374Crossref PubMed Scopus (83) Google Scholar,3ESRD Treatment Choices (ETC) Model. (Accessed 5 October 2022, at https://innovation.cms.gov/innovation-models/esrd-treatment-choices-model.)Google Scholar Simultaneously, there is increased emphasis on improving equity in transplant access, including a revised allocation system (“KAS250”) in March 2021 that removed strict geographic boundaries previously used in local organ allocation in an effort to reduce geographical heterogeneity in transplant rates.4Klarman SE Formica Jr., RN The Broader Sharing of Deceased Donor Kidneys Is an Ethical and Legal Imperative.J Am Soc Nephrol. 2020; 31: 1174-1176Crossref PubMed Scopus (0) Google Scholar However, KAS250 dramatically increased the complexity of interactions between transplant centers and organ procurement organizations (OPOs),5Adler JT Husain SA King KL Mohan S Greater complexity and monitoring of the new Kidney Allocation System: Implications and unintended consequences of concentric circle kidney allocation on network complexity.Am J Transplant. 2021; 21: 2007-2013Abstract Full Text Full Text PDF PubMed Scopus (27) Google Scholar and the impacts of this change on organ utilization are not yet understood. Among these 96,834 DDKs recovered during the study period, 21,411 were discarded (22%), including 13,229/64,281 (21%) pre-KAS250 and 8,182/32,553 (25%) with KAS250 (p=0.004)— an increase that occurred despite similar overall quality of recovered DDKs in both eras (median Kidney Donor Profile Index [KDPI] 48% vs 51%). DDK discard has increased across all adult donor age groups (18-60 years: 16% vs 21%; ≥60 years: 54% vs 60%, Supplemental Figure S1), among DDKs with medium (18% vs 22%) and high KDPI (64% vs 68%; Figure 1A), and for DDKs from donors after both cardiac death (22% vs 31%) and brain death (20% vs 23%; Figure 1B). Discard of low KDPI DDKs was unchanged (3% vs 3%). An interrupted time series analysis also demonstrates an accelerated increase in DDK discards after the policy change (Supplemental Figure S2). DDK discard has also increased broadly among OPOs with high, medium, and low performance ratings (Figure 1C), indicating that this is not a geographic- or OPO-specific concern. The current discard rate for kidneys if present in prior years, after accounting for differences in discard rates for different quality organs, would result in 967 and 805 fewer transplants occurring in 2019 and 2020, respectively (Supplemental Table S1). Importantly, reasons for DDK discard also shifted with KAS250, with a greater proportion of discards attributable to exhaustion of the list of eligible candidates without organ acceptance (Figure 1D), supporting logistical complexity as a driver of worsened utilization. While the absolute number of DDK transplants has increased, over 1 in 4 DDKs recovered for transplant are not being transplanted, representing missed opportunities for hundreds of patients annually and increased healthcare system cost. This unintended deleterious consequence of the allocation system change requires urgent intervention to ensure that priceless organs are not wasted and that efforts to improve geographic equity in transplant do not come at a cost of worsening DDK utilization. SAH is supported by NIDDK grant K23 DK133729. Disclosures None Download .pdf (.27 MB) Help with pdf files

Reexamining the Impact of Insurance Type on Kidney Transplant Waitlist Status and Posttransplantation Outcomes in the United States After Implementation of the Affordable Care Act.

Using Scientific Registry of Transplant Recipients data, we assessed insurance type of waitlisted candidates pre- (2008-2014) versus post- (2014-2021) KAS/ACA using chi-square tests. Next, we performed a competing risk analysis to study the effect of private versus public (Medicare, Medicaid, or government-sponsored) insurance on waitlist outcomes and a Cox survival analysis to study posttransplant outcomes while controlling for candidate, and recipient and donor variables, respectively. The proportion of overall KT candidates insured by Medicaid increased from pre-KAS/ACA to post-KAS/ACA (from 12 667 [7.3%] to 21 768 [8.8%], P < 0.0001). However, KT candidates with public insurance were more likely to have died or become too sick for KT (subdistribution hazard ratio [SHR] = 1.33, confidence interval [CI], 1.30-1.36) or to receive a deceased donor KT (SHR = 1.57, CI, 1.54-1.60) but less likely to receive a living donor KT (SHR = 0.87, CI, 0.85-0.89). Post-KT, KT recipients with public insurance had greater risk of mortality (relative risks = 1.22, CI, 1.15-1.31) and allograft failure (relative risks = 1.10, CI, 1.03-1.29). Although the implementation of ACA marginally increased the proportion of waitlisted candidates with Medicaid, publicly insured KT candidates remained at greater risk of being removed from the waitlist, had lower probability of living donor kidney transplantation, and had greater probability of dying post-KT and allograft failure. Concerted efforts to address factors contributing to these inequities in future studies are needed, with the goal of achieving equity in KT for all.

Allokation von Nieren im Zeitalter des Organmangels in Deutschland

Due to the opt-in solution currently in place in Germany, there is a substantial shortage of deceased organ donors. Therefore, it is critical that the allocation of available organs follows an optimized algorithm and that the potential of living donations is maximized; however, in this respect the current German legislation has major shortcomings. The human leukocyte antigen (HLA) matching system has a large impact on the standard kidney allocation (Eurotransplant kidney allocation system, ETKAS), that is no longer necessary to this extent in the era of modern immunosuppression but continues to put patients with rare HLA types at a disadvantage. As most points are effectively awarded for the accrual of waiting time, kidneys are often awarded to recipients with poor perspectives for organ survival. The aim of the Eurotransplant Senior Program (ESP) is primarily to minimize the cold ischemia time (CIT) even though it has been shown that CIT can be increased to up to 18 h without impairing allograft survival, also for high-risk organs from ≥ 70-year-old donors. At the same time, the preferential allocation of ESP organs within one subregion results in greatly different waiting times within Germany. Also, the only inclusion criterion for the ESP is recipient age, whereas other medical conditions and thus other recipient risk groups (e.g., diabetics) are disadvantaged. The ban on altruistic living kidney donations in Germany impairs the implementation of modern strategies, such as crossover donations, that have become standard internationally. In turn, the full potential of living kidney donations cannot currently be exploited in Germany. The allocation system should be modernized by incorporating new advances from transplantation research, e.g., by allocation according to life years gained.

The new French kidney allocation system for donations after brain death: Rationale, implementation, and evaluation

In recent decades, the allocation policies of many countries have moved from center-based to patient-based approaches. The new French kidney allocation system (KAS) of donations after brain death for adult recipients, implemented in 2015, was principally designed to introduce a unified allocation score (UAS) to be applied locally for one kidney and nationally for the other and to replace regional borders by a new geographical model. The new KAS balances dialysis duration and waiting time to compensate for listing delays and provides more effective longevity matching between donors and recipients with better HLA and age matching. We report these changes, with their rationale and main results. Results show improved HLA matching for young recipients and more rapid access to transplant for older recipients. Young recipients also had better access to transplantation. Transplant access decreased for recipients aged 60-69 and required tuning of KAS parameters. In conclusion, our results strongly indicate that national or adequately broad geographic allocation areas, combined with multiplicative interactions between allocation criteria, permit multivariate optimization of organ allocation and thus improve national kidney sharing and balance HLA matching and age matching, at the price of longer cold ischemic times and more logistical constraints than with local allocation.

ABO-adjusted calculated panel reactive antibody (cPRA): A unified metric for immunologic compatibility in kidney transplantation

Implementation of the kidney allocation system in 2014 greatly reduced access disparity due to human leukocyte antigen (HLA) sensitization. To address persistent disparity related to candidate ABO blood groups, herein we propose a novel metric termed "ABO-adjusted cPRA," which simultaneously considers the impact of candidate HLA and ABO sensitization on the same scale. An ethnic-weighted ABO-adjusted cPRA value was computed for 190 467 candidates on the kidney waitlist by combining candidate's conventional HLA cPRA with the remaining fraction of HLA-compatible donors that are ABO-incompatible. Consideration of ABO sensitization resulted in higher ABO-adjusted cPRA relative to conventional cPRA by HLA alone, except for AB candidates since they are not ABO-sensitized. Within cPRA Point Group=99%, 43% of the candidates moved up to ABO-adjusted cPRA Point Group=100%, though this proportion varied substantially by candidate blood group. Nearly all O and most B candidates would have elevated ABO-adjusted cPRA values above this policy threshold for allocation priority, but relatively few A candidates displayed this shift. Overall, ABO-adjusted cPRA more accurately measures the proportion of immune-compatible donors compared with conventional HLA cPRA, especially for highly sensitized candidates. Implementation of this novel metric could enable the development of allocation policies permitting more ABO-compatible transplants without compromising equity.