Changing organ allocation policy for kidney transplantation in the United States

Inconsistent values and algorithmic fairness: a review of organ allocation priority systems in the United States

BACKGROUND

The Organ Procurement and Transplant Network (OPTN) Final Rule guides national organ transplantation policies, mandating equitable organ allocation and organ-specific priority stratification systems. Current allocation scores rely on mortality predictions.

METHODS

We examined the alignment between the ethical priorities across organ prioritization systems and the statistical design of the risk models in question. We searched PubMed for literature on organ allocation history, policy, and ethics in the United States.

RESULTS

We identified 127 relevant articles, covering kidney (19), liver (60), lung (24), and heart transplants (23), and transplant accessibility (1). Current risk scores emphasize model performance and overlook ethical concerns in variable selection. The inclusion of race, sex, and geographical limits as categorical variables lacks biological basis; therefore, blurring the line between evidence-based models and discrimination. Comprehensive ethical and equity evaluation of risk scores is lacking, with only limited discussion of the algorithmic fairness of the Model for End-Stage Liver Disease (MELD) and the Kidney Donor Risk Index (KDRI) in some literature. We uncovered the inconsistent ethical standards underlying organ allocation scores in the United States. Specifically, we highlighted the exception points in MELD, the inclusion of race in KDRI, the geographical limit in the Lung Allocation Score, and the inadequacy of risk stratification in the Heart Tier system, creating obstacles for medically underserved populations.

CONCLUSIONS

We encourage efforts to address statistical and ethical concerns in organ allocation models and urge standardization and transparency in policy development to ensure fairness, equitability, and evidence-based risk predictions.

Predicting wait time for pediatric kidney transplant: a novel index

BACKGROUND

Over one thousand pediatric kidney transplant candidates are added to the waitlist annually, yet the prospective time spent waiting is unknown for many. Our study fills this gap by identifying variables that impact waitlist time and by creating an index to predict the likelihood of a pediatric candidate receiving a transplant within 1 year of listing. This index could be used to guide patient management by giving clinicians a potential timeline for each candidate's listing based on a unique combination of risk factors.

METHODS

A retrospective analysis of 3757 pediatric kidney transplant candidates from the 2014 to 2020 OPTN/UNOS database was performed. The data was randomly divided into a training set, comprising two-thirds of the data, and a testing set, comprising one-third of the data. From the training set, univariable and multivariable logistic regressions were used to identify significant predictive factors affecting wait times. A predictive index was created using variables significant in the multivariable analysis. The index's ability to predict likelihood of transplantation within 1 year of listing was validated using ROC analysis on the training set. Validation of the index using ROC analysis was repeated on the testing set.

RESULTS

A total of 10 variables were found to be significant. The five most significant variables include the following: blood group, B (OR 0.65); dialysis status (OR 3.67); kidney disease etiology, SLE (OR 0.38); and OPTN region, 5 (OR 0.54) and 6 (OR 0.46). ROC analysis of the index on the training set yielded a c-statistic of 0.71. ROC analysis of the index on the testing set yielded a c-statistic of 0.68.

CONCLUSIONS

This index is a modest prognostic model to assess time to pediatric kidney transplantation. It is intended as a supplementary tool to guide patient management by providing clinicians with an individualized prospective timeline for each candidate. Early identification of candidates with potential for prolonged waiting times may help encourage more living donation including paired donation chains.

Long-term outcomes of liver transplantation for biliary atresia and results of policy changes: over 20 years of follow-up experience

Objective

Biliary atresia (BA) patients develop chronic liver disease after the Kasai operation and are eventually indicated for liver transplantation (LT). The purposes of this study were to analyze long-term outcomes after LT and risk factors that affect complications to reduce graft failure.

Study design

Overall, 145 pediatric patients who underwent LT between June 1996 and June 2020 after a diagnosis of BA were included. We performed a retrospective analysis of medical records and evaluated patient and graft survival, cumulative incidence of complications, risk factors, and the results of policy changes.

Results

Patient and graft survival rates in over 20 years were 95.8% and 91.0%, respectively. Post-transplantation lymphoproliferative disease was frequently observed in the early period of immunosuppression within the first 1-2 years after LT. The incidence of cholangitis and rejection steadily increased over time. Weight-to-portal vein size was evaluated as a risk factor for cholangitis and bile duct strictures (OR = 12.82, p = 0.006 and OR = 16.54, p = 0.015, respectively). When evaluated using 2013 as a reference point, the split graft indication was expanded and the group that received LT after 2013 had a significantly lower survival over time compared with that of the group that received LT before 2013 (p = 0.006).

Conclusion

This study revealed time differences in prevalence of complications. The evaluation of weight-to-duct or vessel size is a more important factor in considering complications than the graft-to-recipient weight ratio. Survival outcomes may have been altered by a policy change that affects the donor type ratio in transplantation.

Evaluating the outcomes of donor-recipient age differences in young adults undergoing liver transplantation

The current liver allocation system may be disadvantaging younger adult recipients as it does not incorporate the donor-recipient age difference. Given the longer life expectancy of younger recipients, the influences of older donor grafts on their long-term prognosis should be elucidated. This study sought to reveal the long-term prognostic influence of the donor-recipient age difference in young adult recipients. Adult patients who received initial liver transplants from deceased donors between 2002 and 2021 were identified from the UNOS database. Young recipients (patients 45 years old or below) were categorized into 4 groups: donor age younger than the recipient, 0-9 years older, 10-19 years older, or 20 years older or above. Older recipients were defined as patients 65 years old or above. To examine the influence of the age difference in long-term survivors, conditional graft survival analysis was conducted on both younger and older recipients. Among 91,952 transplant recipients, 15,170 patients were 45 years old or below (16.5%); these were categorized into 6,114 (40.3%), 3,315 (21.9%), 2,970 (19.6%), and 2,771 (18.3%) for groups 1-4, respectively. Group 1 demonstrated the highest probability of survival, followed by groups 2, 3, and 4 for the actual graft survival and conditional graft survival analyses. In younger recipients who survived at least 5 years post-transplant, inferior long-term survival was observed when there was an age difference of 10 years or above (86.9% vs. 80.6%, log-rank p <0.01), whereas there was no difference in older recipients (72.6% vs. 74.2%, log-rank p =0.89). In younger patients who are not in emergent need of a transplant, preferential allocation of younger aged donor offers would optimize organ utility by increasing postoperative graft survival time.

Refusal of transplant organs for non-medical reasons including COVID-19 status

Transplant centers and physicians in the United States have limited guidance on the information which they can and cannot provide to transplant candidates regarding donors of potential organs. Patients may refuse organs for a variety of reasons ranging from pernicious requests including racism to misinformation about emerging medicine as with the COVID-19 vaccine and infection. Patient autonomy, organ stewardship, and equity are often at odds in these cases, but precedent indeed exists to help address these challenges. This work uses such cases to highlight the urgent need for uniform, national policy prohibiting informational requests unrelated to well-established risks.

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).

Trends in Survival for Pediatric Transplantation

OBJECTIVES

Progress in pediatric transplantation measured in the context of waitlist and posttransplant survival is well documented but falls short of providing a complete perspective for children and their families. An intent-to-treat analysis, in which we measure survival from listing to death regardless of whether a transplant is received, provides a more comprehensive perspective through which progress can be examined.

METHODS

Univariable and multivariable Cox regression was used to analyze factors impacting intent-to-treat survival in 12 984 children listed for heart transplant, 17 519 children listed for liver transplant, and 16 699 children listed for kidney transplant. The Kaplan-Meier method and log-rank test were used to assess change in waitlist, posttransplant, and intent-to-treat survival. Wait times and transplant rates were compared by using χ2 tests.

RESULTS

Intent-to-treat survival steadily improved from 1987 to 2017 in children listed for heart (hazard ratio [HR] 0.96, 95% confidence interval [CI] 0.96-0.97), liver (HR 0.95, 95% CI 0.94-0.97), and kidney (HR 0.97, 95% CI 0.95-0.99) transplant. Waitlist and posttransplant survival also improved steadily for all 3 organs. For heart transplant, the percentage of patients transplanted within 1 year significantly increased from 1987 to 2017 (60.8% vs 68.7%); however, no significant increase was observed in liver (68.9% vs 72.5%) or kidney (59.2% vs 62.7%) transplant.

CONCLUSIONS

Intent-to-treat survival, which is more representative of the patient perspective than individual metrics alone, steadily improved for heart, liver, and kidney transplant over the study period. Further efforts to maximize the donor pool, improve posttransplant outcomes, and optimize patient care while on the waitlist may contribute to future progress.

Life-Years & Rationing in the Covid-19 Pandemic: A Critical Analysis

Prominent bioethicists have promoted the preservation of life-years as a rationing strategy in response to the Covid-19 pandemic. Yet the philosophical justification for maximizing life-years is underdeveloped and has a complex history that is not reflected in recent literature. In this article, we offer a critical investigation of the use of life-years, arguing that evidence of public support for the life-years approach is thin and that organ transplantation protocols (heavily cited in pandemic-response protocols) do not provide a precedent for seeking to save the most life-years. We point out that many state emergency-response plans ultimately rejected or severely attenuated the meaning of saving the most life-years, and we argue that philosophical arguments in support of rationing by life-years are remarkably wanting. We conclude by offering a fair alternative that adheres to the standard duties of beneficence, respect for persons, and justice.

Donor-Recipient Matching in Kidney Transplant: We're Not There Yet

BACKGROUND

Strategic organ allocation is expected to prolong patient and graft survival after transplant. This study explored differences in graft survival when kidneys are allocated based on strategic donor-recipient (D-R) pairing vs with the existing Kidney Allocation System (KAS).

METHODS

Using the Scientific Registry of Transplant Recipients from 2000 to 2014, we used a multivariable Cox model to assess the hazard ratios (HRs) for death or graft failure among 3 hypothetical donor kidneys transplanted into 3 hypothetical recipients, relative to an ideally matched D-R pair. Median predicted survival for each of the 9 possible D-R pairing combinations was determined, and outcomes for strategic D-R pairing were compared with those obtained using the KAS for allocation.

RESULTS

A total of 31,607 patients (29.7%) died or developed graft loss over the study period. Strategic allocation of kidneys resulted in HRs for graft loss of 1.74 (95% confidence interval [CI], 1.41-2.14), 1.82 (95% CI, 1.46-2.26), and 1.74 (95% CI 1.38-2.19) for recipients 1, 2 and 3 respectively, whereas by following the KAS, HRs were 1.93 (95%, CI 1.63-2.28), 2.06 (95% CI, 1.74-2.44), and 1.93 (95% CI, 1.58-2.37); corresponding to 3.84, 11.39, and 7.40 months longer predicted patient or graft survival for recipients 1, 2 and 3 with strategic D-R pairing compared with the KAS.

CONCLUSIONS

Allocation of kidneys by strategic D-R pairing may improve graft survival relative to allocation using the KAS.

Donor-Recipient Matching to Optimize the Utility of High Kidney Donor Profile Index Kidneys

BACKGROUND

In December 2014, the Kidney Donor Profile Index (KDPI) was developed to give more precise information on donor kidney quality. Kidneys with KDPI scores ≥ 85 (K ≥ 85) have been reported to have inferior outcomes to kidneys with KDPI scores < 85.

METHODS

After the implementation of the new Kidney Allocation System, we developed a protocol to evaluate K ≥ 85 use. We analyzed the safety and efficacy of our institutional criteria and evaluated post-transplant outcomes. K ≥ 85 recipients were stratified based on their 1-year creatinine and estimated glomerular filtration rates to elucidate characteristics associated with serum creatinine < 1.7 mg/dL or estimated glomerular filtration rates ≤ 45 mL/min/1.73 m².

RESULTS

From December 2014 to December 2019, 304 deceased donor kidney transplants were performed at Hartford Hospital; 58 (19%) were K ≥ 85 with an average KDPI of 91%. There were 4 graft losses; 2 were death censored. Prolonged cold ischemia time and black recipient race were associated with inferior recipient graft function at 1 year.

CONCLUSIONS

High KDPI kidney use requires a multifaceted evaluation that takes into account donor and recipient characteristics for an ideal match. We have identified several characteristics that may predict optimal post-transplant kidney function.

Donor Ethnicity and Kidney Transplant Outcomes in African Americans

BACKGROUND

Transplantation of African American (AA) compared to non-AA donor kidneys is generally associated with inferior outcomes. It is unclear whether enhanced genetic risk associated with AA donor kidneys would be counterbalanced by favorable immunologic matching when AA donor kidneys are transplanted into AA recipients. We aimed to compare the outcomes of AA vs non-AA deceased-donor kidneys (DDKs) stratified by kidney donor profile index (KDPI) that were transplanted into AA recipients.

METHODS

Using the Organ Procurement and Transplant Network/United Network for Organ Sharing database, we identified AA DDK recipients from 2000 to 2015 who received peri-operative induction followed by calcineurin inhibitor/mycophenolate mofetil maintenance. These patients were divided into 4 KDPI groups (0%-20%, 21%-50%, 51%-85%, and 86%-100%). Adjusted long-term graft and patient outcomes were compared between AA recipients of kidneys from AA vs non-AA donors in each KDPI category using a multivariable Cox model.

RESULTS

Among a total of 17,516 AA DDK transplant recipients, 3303 were in KDPI 0%-20% (AA donor = 239; non-AA donor = 3064), 5821 in KDPI 21%-50% (AA donor = 1414; non-AA donor = 4407), 6364 in KDPI 51%-85% (AA donor = 1619; non-AA donor = 4745), and 2028 in KDPI 86%-100% (AA donor = 932; non-AA donor = 1096) groups. Adjusted overall graft, death-censored graft, and patient survival were similar between AA recipients of AA vs non-AA donor kidneys across all KDPI groups.

DISCUSSION

Our study showed similar outcomes for transplanting AA vs non-AA deceased-donor kidneys into AA recipients despite the generally observed inferior outcomes associated with AA donor kidney transplantation.

Impact of Donor-Recipient Age Difference on Graft Function and Survival After Deceased Donor Kidney Transplantation

BACKGROUND

Donor-recipient age difference (DRAD) is one of the reasons why patients on kidney waiting lists refuse to receive the offered organ. However, its impact on deceased donor kidney transplantation (DDKT) outcomes is still controversial.

METHODS

One hundred fifty-three kidney transplant recipients (KTRs) who received their first-time DDKT were enrolled. The KTRs were divided into groups by DRAD: group 1 (n = 74) (DRAD < 0) and group 2 (n = 79) (DRAD ≥ 0). The KTRs in group 2 were divided into 3 subgroups: DRAD 0 to 10 (n = 35), 10 to 20 (n = 32), and ≥ 20 (n = 12). The outcome measures included estimated glomerular filtration rate (eGFR), delayed graft function (DGF), acute rejection (AR), and graft and patient survival.

RESULTS

There were no significant differences in clinical outcomes between group 1 and 2 except eGFR until 5 years after DDKT. Among the subgroups of group 2, DGF, AR, patient survival, and eGFR until 5 years showed no significant differences. However, graft survival was significantly different (P = .015); in addition, in the DRAD ≥ 20 subgroup, graft survival decreased compared with that in the DRAD 10 to 20 subgroup and DRAD 0 to 10 subgroup (P = .020, P = .012, respectively). In a multivariate Cox proportional hazards analysis, the DRAD ≥ 20 subgroup showed a higher risk for graft failure than the DRAD 0 to 10 subgroup.

CONCLUSIONS

Although donors were of the same age or older than recipients, DDKT showed acceptable graft outcomes. However, because donors over 20 years older than recipients showed a decreased graft survival, it might be important to consider this point in donor-recipient matching of DDKT.

Assessment of the Kidney Donor Profile Index in a European cohort

Background

Recently, transplant societies have had to change their allocation policies to counter global organ shortages. However, strategies differ significantly and long-term outcomes and cross-regional applicability remain to be evaluated.

Methods

Therefore, we retrospectively analysed the Kidney Donor Profile Index (KDPI) of 987 adult kidney transplants at our centre using data from the Organ Procurement and Transplantation Network (OPTN) as a reference.

Results

In our cohort, the median KDPI was 66%, with a higher proportion of >85% KDPI kidneys compared with the US cohort (32.3% versus 9.2%). Among elderly patients (≥65 years of age), 62% received >95% KDPI kidneys, which were primarily allocated within the Eurotransplant Senior Program (ESP). After 10 years, the rate of death-censored graft survival was 70.5%. Recipients of >85% KDPI kidneys were significantly older, demonstrating higher mortality, poorer graft survival and lower estimated glomerular filtration rate. Patients receiving ≥99% KDPI kidneys had a satisfactory 5-year death-censored graft survival (72.9%). The 5-year survival rate of patients living with a functioning graft exceeded the matched OPTN data in the whole KDPI range, despite a higher proportion of elderly recipients. Multivariate analysis revealed KDPI as an independent risk factor for graft loss (hazard ratio 1.14/10%, P < 0.001), although C-statistics of 0.62 indicated limited discriminative ability for individuals.

Conclusion

The analysis demonstrated KDPI as a potentially useful tool for donor quality assessment in a European cohort. Most importantly, our analysis revealed acceptable outcomes even for very high KDPI kidneys.

Survival analysis of patients in the waiting list for kidney transplantation in terms of competing risks

Aim: to analyze the survival of patients on the waiting list for kidney transplantation and the results of transplantation depending on the duration of waiting.

Materials and methods. We performed a retrospective observational analysis that included 1,197 patients on the waiting list. The end point was exclusion from the waiting list (WL). The causes for exclusion (death, exclusion due to deterioration of the comorbid background or transplantation) were considered in terms of competing risks.

Results. In total, 72.5% of patients reached the end point: 21.1% of them died, 11% were excluded, and 40.4% underwent transplantation. Kaplan–Meier estimate showed that cumulative risk of death was 80.4% [95% CI 77.9; 88.6], of exclusion was 77.9% [95% CI 65.4; 88.2], of transplantation was 63.6% [95% CI 58.3; 69] after 10 years on the waiting list. However, such an assessment cannot be directly interpreted as a prediction of the relevant event risk of occurrence for the patient in the WL, because it does not take into account competing events. According to a balanced assessment of the competing risks (Fine and Gray estimate), cumulative incidence was 30.9% (95% CI 27.7; 34.2) for death, 18.2% [95% CI 15.5; 21.1] for exclusion and 49.4% [95% CI 46; 52.6%] for transplantation after 10 years on WL. The probability of transplantation was significantly higher than the risk of death up to and including 5 years of waiting (incidence rate ratio – IRR 1.769 [95% CI 1.098; 2.897]). When waiting 7 to 8 years, the probability of transplantation was less than the risk of death: IRR 0.25 (95% CI 0.093; 0.588; p = 0.0009). Of the 483 recipients, 61 died and 119 returned to dialysis. The risk of graft loss after 10 years was 68.5% [95% CI 57.5; 79.1] and the risk of death of a recipient with a functioning graft was 48.3% [95% CI 34.7; 63] according to Kaplan–Meier estimate. The cumulative incidence of the method was 30.8% [95% CI 23.3; 38.5%] and 55.7% [95% CI 46.6; 63.5%] according to Fine and Gray estimate, respectively. The risk of death after transplantation increases significantly when waiting for more than 6 years – IRR 4.325 [95% CI 1.649; 10.47], p = 0.0045 relative to a shorter waiting period. With an increase in the waiting period, the comorbid background (CIRS scale) deteriorates significantly, even adjusted for the initial patient condition: the partial correlation r = 0.735; p < 0.0001.

Conclusion. 1. In the context of competing risks, the Fine and Gray estimate gives a more balanced risk assessment compared to the Kaplan–Meier method. 2. Increasing the waiting time for transplantation significantly increases the risk of death of the candidate on the waiting list and reduces the probability of transplantation, as well as increases the risk of death of the recipient after transplantation. Apparently, this is mainly due to the deterioration of the comorbid background.

Retransplant Outcomes Compared With First Kidney Transplants: Important Observations Not Reported in the Scientific Registry of Transplant Recipients Annual Report

OBJECTIVES

Twice per year, the Scientific Registry of Transplant Recipients provides risk-adjusted center-specific reports of 1- and 3-year outcomes. In addition, the Registry reports 10-year aggregate survival outcomes for kidney transplant recipients. However, in this annual report, no distinction is made between outcomes of patients with a first transplant versus those with retransplants.

MATERIALS AND METHODS

We analyzed data from the Scientific Registry of Transplant Recipients between 1992 and 2015 to determine outcomes after a 1st, 2nd, or ≥ 3rd kidney transplant. Recipients were stratified by donor source (living vs deceased) and transplant number, and rates of graft failure, death-censored graft failure, and death with functioning graft were determined.

RESULTS

From 1992 to 2015, rates of graft failure and death-censored graft failure at 6 months, 1 year, 3 years, 5 years, and 10 years decreased; however, long-term rates of death with functioning graft were unchanged. Outcomes for 1st and 2nd kidney transplant were better than outcomes for ≥ 3rd transplant.

CONCLUSIONS

It would be extremely valuable if the Scientific Registry of Transplant Recipients could present stratified analyses that would account for a host of factors, including organ sequence, which tend to vary by center. The presentation of risk-adjusted outcomes in the annual Registry report could include a more comprehensive assessment of program performance. Such information would be extremely useful for transplant centers, patients, and their support networks, organ procurement organizations, and other transplant stakeholders.

Emerging approaches and technologies in transplantation: the potential game changers

Newly emerging technologies are rapidly changing conventional approaches to organ transplantation. In the modern era, the key challenges to transplantation include (1) how to best individualize and possibly eliminate the need for life-long immunosuppression and (2) how to expand the donor pool suitable for human transplantation. This article aims to provide readers with an updated review of three new technologies that address these challenges. First, single-cell RNA sequencing technology is rapidly evolving and has recently been employed in settings related to transplantation. The new sequencing data indicate an unprecedented cellular heterogeneity within organ transplants, as well as exciting new molecular signatures involved in alloimmune responses. Second, sophisticated nanotechnology platforms provide a means of therapeutically delivering immune modulating reagents to promote transplant tolerance. Tolerogenic nanoparticles with regulatory molecules and donor antigens are capable of targeting host immune responses with tremendous precision, which, in some cases, results in donor-specific tolerance. Third, CRISPR/Cas9 gene editing technology has the potential to precisely remove immunogenic molecules while inserting desirable regulatory molecules. This technology is particularly useful in generating genetically modified pigs for xenotransplantation to solve the issue of the shortage of human organs. Collectively, these new technologies are positioning the transplant community for major breakthroughs that will significantly advance transplant medicine.

Kidney transplantation in older recipients: Preemptive high KDPI kidney vs lower KDPI kidney after varying dialysis vintage

AIM

To evaluate the outcomes of transplanting marginal kidneys preemptively compared to better-quality kidneys after varying dialysis vintage in older recipients.

METHODS

Using OPTN/United Network for Organ Sharing database from 2001-2015, we identified deceased donor kidney (DDK) transplant recipients > 60 years of age who either underwent preemptive transplantation of kidneys with kidney donor profile index (KDPI) ≥ 85% (marginal kidneys) or received kidneys with KDPI of 35%-84% (better quality kidneys that older wait-listed patients would likely receive if waited longer) after being on dialysis for either 1-4 or 4-8 years. Using a multivariate Cox model adjusting for donor, recipient and transplant related factors- overall and death-censored graft failure risks along with patient death risk of preemptive transplant recipients were compared to transplant recipients in the 1-4 and 4-8 year dialysis vintage groups.

RESUTLS

The median follow up for the whole group was 37 mo (interquartile range of 57 mo). A total of 6110 DDK transplant recipients above the age of 60 years identified during the study period were found to be eligible to be included in the analysis. Among these patients 350 received preemptive transplantation of kidneys with KDPI ≥ 85. The remaining patients underwent transplantation of better quality kidneys with KDPI 35-84% after being on maintenance dialysis for either 1-4 years (n = 3300) or 4-8 years (n = 2460). Adjusted overall graft failure risk and death-censored graft failure risk in preemptive high KDPI kidney recipients were similar when compared to group that received lower KDPI kidney after being on maintenance dialysis for either 1-4 years (HR 1.01, 95%CI: 0.90-1.14, P = 0.84 and HR 0.96, 95%CI: 0.79-1.16, P = 0.66 respectively) or 4-8 years (HR 0.82, 95%CI: 0.63-1.07, P = 0.15 and HR 0.81, 95%CI: 0.52-1.25, P = 0.33 respectively). Adjusted patient death risk in preemptive high KDPI kidney recipients were similar when compared to groups that received lower KDPI kidney after being on maintenance dialysis for 1-4 years (HR 0.99, 95%CI: 0.87-1.12, P = 0.89) but lower compared to patients who were on dialysis for 4-8 years (HR 0.74, 95%CI: 0.56-0.98, P = 0.037).

CONCLUSION

In summary, our study supports accepting a “marginal” quality high KDPI kidney preemptively in older wait-listed patients thus avoiding dialysis exposure.

Unintended Consequences in Use of Increased Risk Donor Kidneys in the New Kidney Allocation Era

BACKGROUND

The new kidney allocation system (KAS) intends to allocate the top 20% of kidneys to younger recipients with longer life expectancy. We hypothesized that the new KAS would lead to greater allocation of Public Health Service (PHS) increased-risk donor organs to younger recipients.

METHODS

Analyses of the Organ Procurement and Transplantation Network data of patients who underwent primary deceased kidney transplantation were performed in pre- and post-KAS periods.

RESULTS

The allocation of PHS increased-risk kidney allografts in various age groups changed significantly after implementation of the new KAS, with an increased proportion of younger individuals receiving increased-risk kidneys (7% vs 10% in age group 20-29 y and 13% vs 18% in age group 30-39 y before and after KAS, respectively; P < .0001). This trend was reversed in recipients 50-59 years old, with 31% in the pre-KAS period compared with 26% after KAS (P < .0001).

CONCLUSIONS

The new KAS resulted in a substantial increase in allocation of PHS increased-risk kidneys to candidates in younger age groups. Because increased-risk kidneys are generally underutilized, future efforts to optimize the utilization of these organs should target younger recipients and their providers.

Evolving Trends in Racial Disparities for Peri-Operative Outcomes with the New Kidney Allocation System (KAS) Implementation

INTRODUCTION

To improve kidney transplant allocation equitability, a new Kidney Allocation System (KAS) was implemented December 4, 2014. The purpose of this study was to determine if the impact of KAS on peri-operative outcomes differed by recipient race/ethnicity.

METHODS

This was a time series analysis using data aggregated in monthly intervals from October 2012 through September 2015 using the University HealthSystem Consortium (UHC). This includes national data aggregated at the center level of all US kidney transplant centers that participate in the UHC (416 centers). Segmented regression with interaction terms was used to determine the impact of KAS on outcomes and differences by race/ethnicity.

RESULTS

A total of 28,809 deceased donor kidney transplants were included with 25 months of pre-KAS data and 10 months of post-KAS data. After KAS implementation, the estimated transplant rate per month decreased significantly for Caucasians by 17.6 cases per month (p = 0.0001), and increased significantly for AAs by 37.8 (p = 0.0001), Hispanics by 16.3 (p = 0.0001), and other races by 8.2 cases per month (p = 0.0001). Delayed graft function, 7- and 14-day readmissions significantly increased after KAS, which did not differ by race. Hispanics saw a 7.7% decrease in ICU admissions after KAS, which differed as compared to other racial/ethnic cohorts (p = 0.0026). Costs of kidney transplantation increased significantly after KAS in all groups except Hispanics. Mortality, length of stay, in-hospital complications, and 30-day readmissions were not significantly impacted by KAS, also not differing by race/ethnicity.

CONCLUSION

KAS had substantial impact on transplant rates by race/ethnicity. KAS also led to increased costs, readmissions, and delayed graft function (DGF) across all racial/ethnic groups. The impact of KAS on ICU cases solely within Hispanics requires further investigation into potential etiologies.

Analysis of Distribution of Expanded- and Standard-Criteria Donors and Complications Among Polish Recipients by Kidney Donor Risk Index Value

INTRODUCTION

The approach toward transplanting kidneys from expanded-criteria donors (ECDs) in Poland is largely site-dependent. The Kidney Donor Risk Index (KDRI) allows for obtaining a more precise characteristic of ECDs and further stratification into "better" and "worse" quality grafts.

METHODS

Comparison of the incidence of delayed graft function (DGF) and biopsy-proven acute rejection (BPAR), median of hospitalization time and median of estimated glomerular filtration rate (eGFR) at 1 year after transplantation among kidney graft recipients (n = 468), divided by donor status (ECD/standard-criteria donor [SCD]) and KDRI value (I: 0.67-1.2, II: 1.21-1.6, III: 1.61-2.0, IV: 2.01-3.48).

RESULTS

ECD kidneys have been transplanted to 32.47% of recipients. There were no ECD recipients in KDRI compartment I, 16.55% in compartment II, 79.22% in compartment III, and 100% in IV. In KDRI compartment II, DGF was diagnosed in 34.9% of SCDs and 56% of ECDs (P = .003), BPAR occurred in 7.8% of SCDs and 16% of ECDs (P = .073), median hospital stay was 12 days for SCDs and ECDs (P = 1), and eGFR was 50.7 mL/min for SCDs and 49.4 mL/min for ECDs (P = .734). In KDRI compartment III, DGF was diagnosed in 43.8% of SCDs and 49.2% of ECDs (P = .139), BPAR occurred in 6.3% of SCDs and 31.7% of ECDs (P = .001), median hospital stay was 10 days for SCDs and 12 days for ECDs (P = .634), and eGFR was 49.5 mL/min for SCDs and 45.2 mL/min for ECDs (P = .382). Among ECD recipients, DGF was diagnosed in 56.0%, 49.2%, and 47.7% of patients for KDRI compartments II, III, and IV respectively (P = .776); BPAR occurred in 16% (compartment II), 31.7% (compartment III), and 23.1% (compartment IV) (P = .273); the median hospital stay was 12 days (compartment II), 12 days (compartment III), and 12.5 days (compartment IV) (P = 1); and eGFR was 49.5 mL/min (compartment II), 45.4 mL/min (compartment III), and 36.1 mL/min (compartment IV) (P = .002).

CONCLUSION

Assessment using both the ECD and KDRI systems allows for a more precise evaluation of prognosis and predicting complications among recipients.

Limitation of Terminal Serum Creatinine as a Kidney Donor Profile Index Variable in Predicting Long-Term Kidney Transplant Outcomes

BACKGROUND

Donor final serum creatinine (SCr) is a dynamic variable and is 1 of 10 factors used in calculating kidney donor profile index (KDPI). We hypothesize that deceased-donor kidneys (DDKs) with higher SCr were likely accepted for transplantation if procurement biopsy findings were favorable and with long-term outcomes no worse than kidneys with lower final SCr within a KDPI group.

METHODS

Using the Organ Procurement and Transplant Network/United Network for Organ Sharing database, we identified DDK transplant recipients from 2000 to 2015 who received induction and calcineurin inhibitor/mycophenolate mofetil maintenance. Patients were divided into 4 KDPI groups: 0-20%, 21%-50%, 51%-85%, and >85%. In each KDPI category, long-term outcomes were compared, with the use of Cox models, between patients who received kidneys with final SCr >2 versus ≤2 mg/dL.

RESULTS

A total of 59,644 patients were divided into KDPI groups 0-20% (SCr >2 mg/dL, n = 478; SCr ≤2 mg/dL, n = 14,769), 21%-50% (SCr >2 mg/dL, n = 1,592; SCr ≤2 mg/dL, n = 17,762), 51%-85% (SCr >2 mg/dL; n = 1,388, SCr ≤2 mg/dL, n = 18,024), and >85% (SCr >2 mg/dL, n = 349; SCr ≤2 mg/dL, n = 5,282). Adjusted overall graft failure risks (hazard ratio [HR] 0.88, P = .04; HR, 0.86, P = .007) and patient death risks (HR, 0.86, P = .04; HR, 0.84, P = .01) for final SCr >2 versus ≤2 mg/dL groups were lower in KDPI categories 21%-50% and 51%-85%, respectively, with similar death-censored graft failure risks.

DISCUSSION

Outcomes of transplanting DDKs with elevated final SCr are no worse than transplanting kidneys with lower final SCr, highlighting the limitation of the single value of final SCr as a variable for calculating KDPI.

Predictors of Deceased Donor Kidney Discard in the United States

BACKGROUND

Renal transplantation is a lifesaving intervention for end-stage renal disease. The demand for renal transplantation outweighs the availability of organs; however, up to 20% of recovered kidneys are discarded before transplantation. We aimed to better characterize the risk factors for deceased donor kidney discard.

METHODS

We performed a secondary analysis of the Organ Procurement and Transplantation Network database from 2000 to 2012 of all solid organ donors. The cohort was split into training (80%) and validation (20%) subsets. We performed a stepwise logistic regression to develop a multivariate risk prediction model for kidney graft discard and validated the model. The performance of the models was evaluated with respect to calibration, and area under the curve (AUC) of receiver operating characteristic curves.

RESULTS

There were no significant baseline differences between the training (n = 57 474) and validation (n = 14 368) cohorts. The multivariate model validation showed very good discriminant function in predicting kidney discard (AUC = 0.84). Predictors of increased discard included age older than 50 years, performance of a kidney biopsy, cytomegalovirus seropositive status, donation after cardiac death, hepatitis B and C seropositive status, cigarette use, diabetes, hypertension, terminal creatinine greater than 1.5 mg/dL and AB blood type. The model outperformed the Kidney Donor Risk Index in predicting discard (P < 0.001). Subgroup analysis of expanded criteria donor kidneys demonstrated good discrimination with an AUC of 0.70.

CONCLUSIONS

We have characterized several important predictors of deceased donor kidney discard. Better understanding of factors that lead to increased deceased donor kidney discard can allow for targeted interventions to reduce discard.

The New Kidney Donor Allocation System and Implications for Anesthesiologists

Given potential disparity and limited allocation of deceased donor kidneys for transplantation, a new federal kidney allocation system was implemented in 2014. Donor organ function and estimated recipient survival in this system has implications for perioperative management of kidney transplant recipients. Early analysis suggests that many of the anticipated goals are being attained. For anesthesiologists, implications of increased dialysis duration and burdens of end-stage renal disease include increased cardiopulmonary disease, challenging fluid, hemodynamic management, and central vein access. With no recent evidence to guide anesthesia care within this new system, we describe the kidney allocation system, summarize initial data, and briefly review organ systems of interest to anesthesiologists. As additional invasive and echocardiographic monitoring may be indicated, one consideration may be development of a dedicated anesthesiology team experienced in management and monitoring of complex patients, in a similar manner as has been done for liver transplant recipients.

Selection of Patients for Initial Clinical Trials of Solid Organ Xenotransplantation

Several groups have reported extended survival of genetically engineered pig organs in nonhuman primates, varying from almost 10 months for life-supporting kidney grafts and more than 2 years for non-life-supporting heart grafts to less than 1 month for life-supporting liver and lung grafts. We have attempted to define groups of patients who may not have an option to wait for an allograft. These include kidney, heart, and lung candidates who are highly-allosensitized. In addition, some kidney candidates (who have previously lost at least 2 allografts from rapid recurrence of native kidney disease) have a high risk of further recurrence and will not be offered a repeat allotransplant. Patients with complex congenital heart disease, who may have undergone previous palliative surgical procedures, may be unsuitable for ventricular assist device implantation. Patients dying of fulminant hepatic failure, for whom no alternative therapy is available, may be candidates for a pig liver, even if only as a bridge until an allograft becomes available. When the results of pig organ xenotransplantation in nonhuman primates suggest a realistic potential for success of a pilot clinical trial, highly selected patients should be offered participation.

New Organ Allocation System for Combined Liver-Kidney Transplants and the Availability of Kidneys for Transplant to Patients with Stage 4-5 CKD

A new proposal has been created for establishing medical criteria for organ allocation in recipients receiving simultaneous liver-kidney transplants. In this article, we describe the new policy, elaborate on the points of greatest controversy, and offer a perspective on the policy going forward. Although we applaud the fact that simultaneous liver-kidney transplant activity will now be monitored and appreciate the creation of medical criteria for allocation in simultaneous liver-kidney transplants, we argue that some of the criteria proposed, especially those for allocating a kidney to a liver recipient with AKI, are too liberal. We call on the nephrology community to follow the consequences of this new policy and push for a re-examination of the longstanding policy of allocating kidneys to multiorgan transplant recipients before all other candidates. The charge to protect our system of equitable organ allocation is very challenging, but it is a challenge that we must embrace.

Advances in liver transplantation allocation systems

With the growing number of patients in need of liver transplantation, there is a need for adopting new and modifying existing allocation policies that prioritize patients for liver transplantation. Policy should ensure fair allocation that is reproducible and strongly predictive of best pre and post transplant outcomes while taking into account the natural history of the potential recipients liver disease and its complications. There is wide acceptance for allocation policies based on urgency in which the sickest patients on the waiting list with the highest risk of mortality receive priority. Model for end-stage liver disease and Child-Turcotte-Pugh scoring system, the two most universally applicable systems are used in urgency-based prioritization. However, other factors must be considered to achieve optimal allocation. Factors affecting pre-transplant patient survival and the quality of the donor organ also affect outcome. The optimal system should have allocation prioritization that accounts for both urgency and transplant outcome. We reviewed past and current liver allocation systems with the aim of generating further discussion about improvement of current policies.

BARTERING FOR A COMPATIBLE KIDNEY USING YOUR INCOMPATIBLE, LIVE KIDNEY DONOR: LEGAL AND ETHICAL ISSUES RELATED TO KIDNEY CHAINS

Kidney chains are a recent and novel method of increasing the number of available kidneys for transplantation and have the potential to save thousands of lives. However, because they are novel, kidney chains do not fit neatly within existing legal and ethicalframeworks, raising potential barriers to their full implementation. Kidney chains are an extension of paired kidney donation, which began in the United States in 2000. Paired kidney donations allow kidney patients with willing, but incompatible, donors to swap donors to increase the number of donor/recipient pairs and consequently, the number of transplants. More recently, transplant centers have been using non-simultaneous, extended, altruistic donor ("NEAD") kidney chains--which consist of a sequence of donations by incompatible donors--to further expand the number of donations. This Article fully explains paired kidney donation and kidney chains and focuses on whether NEAD chains are more coercive than traditional kidney donation to a family member or close friend and whether NEAD chains violate the National Organ Transplant Act's prohibition on the transfer of organs for valuable consideration.