Transplanting kidneys without points for HLA-B matching: consequences of the policy change

Balancing Equity and HLA Matching in Deceased-Donor Kidney Allocation with Eplet Mismatch

Background

Prioritization of HLA antigen-level matching in the US kidney allocation system intends to improve post-transplant survival but causes racial disparities and thus has been substantially de-emphasized. Recently, molecular matching based on eplets has been found to improve risk stratification compared to antigen matching.

Methods

To assign eplets unambiguously, we utilized a cohort of 5193 individuals with high resolution allele-level HLA genotypes from the National Kidney Registry. Using repeated random sampling to simulate donor-recipient genotype pairings based on the ethnic composition of the historical US deceased donor pool, we profiled the percentage of well-matched donors for candidates by ethnicity.

Results

The percentage of well-matched donors with zero-DR/DQ eplet mismatch was 3-fold less racially disparate for Black and Asian candidates than percentage of donors with zero-ABDR antigen mismatches, and 2-fold less racially disparate for Latino candidates. For other HLA antigen and eplet mismatch thresholds, the percentage of well-matched donors was more similar across candidate ethnic groups.

Conclusions

Compared to the current zero-ABDR antigen mismatch, prioritizing a zero-DR/DQ eplet mismatch in allocation would decrease racial disparities and increase the percentage of well-matched donors. High resolution HLA deceased donor genotyping would enable unambiguous assignment of eplets to operationalize molecular mismatch metrics in allocation.

Key Points

Question: What is the impact of prioritizing low molecular mismatch transplants on racial and ethnic disparities in US deceased-donor kidney allocation, compared to the current prioritization of antigen-level matching?Findings: The lowest-risk eplet mismatch approach decreases racial disparities up to 3-fold compared to lowest-risk antigen mismatch and identifies a larger number of the lowest allo-immune risk donors.Meaning: Prioritizing eplet matching in kidney transplant allocation could both improve outcomes and reduce racial disparities compared to the current antigen matching.

Impact of OPTN policy 3.7D providing waiting time modification for candidates affected by race-inclusive eGFR calculations: Early results from a single center

INTRODUCTION

OPTN Policy 3.7D, implemented January 5, 2023, mandates that all kidney transplant programs modify waiting time for candidates affected by race-inclusive eGFR calculations. We report the early impact of this policy change.

METHODS

Our transplant program reviewed all listed transplant candidates and identified patients potentially eligible for waiting time modification. Eligible candidates received waiting time modification after submission of supporting evidence to the OPTN. We reviewed the impact on waiting time and transplant activity through October 1, 2023.

RESULTS

Forty-six adult patients on our center's active waiting list self-identified as Black/African American. 25 (54.3%) candidates qualified for waiting time modification. A median 451 (321, 1543.5) additional days of waiting time was added for qualifying patients. Of the 25 patients who qualified for waiting time modification, 11 patients received a deceased donor kidney in the early period following waiting time modification, including 5 patients transplanted within 1 month after modification.

CONCLUSIONS

Policy 3.7D is one of few national mandates to address specifically structural racism within transplantation. Implementation has yielded near immediate effects with greater than 40% of time-adjusted patients at our center receiving a deceased donor kidney transplant in the initial months after policy enactment. Early assessment demonstrates great potential impact for this policy.

Communicating About Precision Transplantation Tools

Purpose of review

Precision tools that ensure molecular compatibility can help prevent rejection and improve kidney transplantation outcomes. However, these tools will generate controversy because they are perceived to and can in fact impact equity in the ethics of allocation. They may also affect the extent to which physicians can advocate for their patient fiduciaries, as generally required by Canadian professional ethics and law.

Sources of information

Electronic databases such as Google Scholar and PubMed were searched for peer-reviewed literature, and Google search engine was used to identify the news articles, jurisprudence, legal information, and other relevant websites cited.

Methods

We discuss controversies precision transplantation tools will likely generate, consider what challenges will arise from their implementation, and provide recommendations of avenues and content for communication to address these issues.

Key findings

Communication about the translation of new precision tools will be challenging as media portrayals of transplantation often focus on individual narratives about access to transplantation and fail to center the issues of utility, allocation, and rejection. Incomplete portrayals of this nature will need to be countered with explanations of how new precision tools can be of net benefit when implemented equitably, as maintaining trust in the donation and transplantation system is key.

Limitations

Our manuscript focuses on precision medicine applications pertaining to the implementation of molecular compatibility in transplantation. Distinct communication content and avenues may need to be considered in other contexts.

Implications

Clear, accurate, and strategic communication is key to managing translation of precision medicine tools. For this purpose, we provide detailed recommendations for stakeholder engagement, content, and avenues for communicating about precision transplantation tools.

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 4 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.

Kidney Allocation Policy: Past, Present, and Future

Despite an increase in the number of kidney transplants performed annually, there remain more than 90,000 individuals awaiting transplantation in the United States. As kidney transplantation has evolved, so has kidney allocation policies. The Kidney Allocation System, which was introduced in 2014, made significant strides to improve utility and equity, but regional and geographic disparities remain. Further modifications eliminating donor service areas have been introduced. Moving forward, systems involving continuous distribution and artificial intelligence may provide further advancement toward an ideal allocation system.

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.

Impact of HLA Mismatching on Early Subclinical Inflammation in Low-Immunological-Risk Kidney Transplant Recipients

The impact of human leukocyte antigen (HLA)-mismatching on the early appearance of subclinical inflammation (SCI) in low-immunological-risk kidney transplant (KT) recipients is undetermined. We aimed to assess whether HLA-mismatching (A-B-C-DR-DQ) is a risk factor for early SCI. As part of a clinical trial (Clinicaltrials.gov, number NCT02284464), a total of 105 low-immunological-risk KT patients underwent a protocol biopsy on the third month post-KT. As a result, 54 presented SCI, showing a greater number of total HLA-mismatches (p = 0.008) and worse allograft function compared with the no inflammation group (48.5 ± 13.6 vs. 60 ± 23.4 mL/min; p = 0.003). Multiple logistic regression showed that the only risk factor associated with SCI was the total HLA-mismatch score (OR 1.32, 95%CI 1.06-1.64, p = 0.013) or class II HLA mismatching (OR 1.51; 95%CI 1.04-2.19, p = 0.032) after adjusting for confounder variables (recipient age, delayed graft function, transfusion prior KT, and tacrolimus levels). The ROC curve illustrated that the HLA mismatching of six antigens was the optimal value in terms of sensitivity and specificity for predicting the SCI. Finally, a significantly higher proportion of SCI was seen in patients with >6 vs. ≤6 HLA-mismatches (62.3 vs. 37.7%; p = 0.008). HLA compatibility is an independent risk factor associated with early SCI. Thus, transplant physicians should perhaps be more aware of HLA mismatching to reduce these early harmful lesions.

Low Hydrophobic Mismatch Scores Calculated for HLA-A/B/DR/DQ Loci Improve Kidney Allograft Survival

We evaluated the impact of human leukocyte antigen (HLA) disparity (immunogenicity; IM) on long-term kidney allograft survival. The IM was quantified based on physicochemical properties of the polymorphic linear donor/recipient HLA amino acids (the Cambridge algorithm) as a hydrophobic, electrostatic, amino acid mismatch scores (HMS\AMS\EMS) or eplet mismatch (EpMM) load. High-resolution HLA-A/B/DRB1/DQB1 types were imputed to calculate HMS for primary/re-transplant recipients of deceased donor transplants. The multiple Cox regression showed the association of HMS with graft survival and other confounders. The HMS integer 0–10 scale showed the most survival benefit between HMS 0 and 3. The Kaplan–Meier analysis showed that: the HMS=0 group had 18.1-year median graft survival, a 5-year benefit over HMS>0 group; HMS ≤ 3.0 had 16.7-year graft survival, a 3.8-year better than HMS>3.0 group; and, HMS ≤ 7.8 had 14.3-year grafts survival, a 1.8-year improvement over HMS>7.8 group. Stratification based on EMS, AMS or EpMM produced similar results. Additionally, the importance of HLA-DR with/without -DQ IM for graft survival was shown. In our simulation of 1,000 random donor/recipient pairs, 75% with HMS>3.0 were re-matched into HMS ≤ 3.0 and the remaining 25% into HMS≥7.8: after re-matching, the 13.5 years graft survival would increase to 16.3 years. This approach matches donors to recipients with low/medium IM donors thus preventing transplants with high IM donors.

Association of Socioeconomic Status and Comorbidities with Racial Disparities during Kidney Transplant Evaluation

BACKGROUND AND OBJECTIVES

Black patients referred for kidney transplantation have surpassed many obstacles but likely face continued racial disparities before transplant. The mechanisms that underlie these disparities are unclear. We determined the contributions of socioeconomic status (SES) and comorbidities as mediators to disparities in listing and transplant.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We studied a cohort (n=1452 black; n=1561 white) of patients with kidney failure who were referred for and started the transplant process (2009-2018). We estimated the direct and indirect effects of SES (self-reported income, education, and employment) and medical comorbidities (self-reported and chart-abstracted) as mediators of racial disparities in listing using Cox proportional hazards analysis with inverse odds ratio weighting. Among the 983 black and 1085 white candidates actively listed, we estimated the direct and indirect effects of SES and comorbidities as mediators of racial disparities on receipt of transplant using Poisson regression with inverse odds ratio weighting.

RESULTS

Within the first year, 876 (60%) black and 1028 (66%) white patients were waitlisted. The relative risk of listing for black compared with white patients was 0.76 (95% confidence interval [95% CI], 0.69 to 0.83); after adjustment for SES and comorbidity, the relative risk was 0.90 (95% CI, 0.83 to 0.97). The proportion of the racial disparity in listing was explained by SES by 36% (95% CI, 26% to 57%), comorbidity by 44% (95% CI, 35% to 61%), and SES with comorbidity by 58% (95% CI, 44% to 85%). There were 409 (42%) black and 496 (45%) white listed candidates transplanted, with a median duration of follow-up of 3.9 (interquartile range, 1.2-7.1) and 2.8 (interquartile range, 0.8-6.3) years, respectively. The incidence rate ratio for black versus white candidates was 0.87 (95% CI, 0.79 to 0.96); SES and comorbidity did not explain the racial disparity.

CONCLUSIONS

SES and comorbidity partially mediated racial disparities in listing but not for transplant.

Policy Challenges for Organ Allocation in an Era of "Precision Medicine"

There is increasing interest in the use of precision medicine tools and evidence-based outcome measures for donor-recipient matching to optimize transplant outcomes. Although the shift toward greater precision can provide health and resource benefits, it may be perceived as conflicting with both established equity-focused organ allocation norms and the legal and ethical obligations of health care providers and related institutions. With increasing evidence that various forms of human leukocyte antigen (HLA) mismatch and/or prognostic biomarkers can affect outcomes, the tension between maximizing utility and ensuring equity seems likely to intensify. In Canada, health care providers are generally required by law to put the interests of their patient, such as access to an organ, above the needs of the health care system and other patients. In addition, transplantation right of access lawsuits, which have been successful in the past, could affect the implementation of precision approaches. These legal tensions could be further heightened by media representations, which have historically favored strong rights of access. When implementing new precision technologies in organ allocation, there will be a recurrent need for policymakers to revisit the balance of equity and utility and to assess how to craft rules that reflect our society’s conception of a fair allocation system.

Racial/ethnic disparities in waitlisting for deceased donor kidney transplantation 1 year after implementation of the new national kidney allocation system

The impact of a new national kidney allocation system (KAS) on access to the national deceased-donor waiting list (waitlisting) and racial/ethnic disparities in waitlisting among US end-stage renal disease (ESRD) patients is unknown. We examined waitlisting pre- and post-KAS among incident (N = 1 253 100) and prevalent (N = 1 556 954) ESRD patients from the United States Renal Data System database (2005-2015) using multivariable time-dependent Cox and interrupted time-series models. The adjusted waitlisting rate among incident patients was 9% lower post-KAS (hazard ratio [HR]: 0.91; 95% confidence interval [CI], 0.90-0.93), although preemptive waitlisting increased from 30.2% to 35.1% (P < .0001). The waitlisting decrease is largely due to a decline in inactively waitlisted patients. Pre-KAS, blacks had a 19% lower waitlisting rate vs whites (HR: 0.81; 95% CI, 0.80-0.82); following KAS, disparity declined to 12% (HR: 0.88; 95% CI, 0.85-0.90). In adjusted time-series analyses of prevalent patients, waitlisting rates declined by 3.45/10 000 per month post-KAS (P < .001), resulting in ≈146 fewer waitlisting events/month. Shorter dialysis vintage was associated with greater decreases in waitlisting post-KAS (P < .001). Racial disparity reduction was due in part to a steeper decline in inactive waitlisting among minorities and a greater proportion of actively waitlisted minority patients. Waitlisting and racial disparity in waitlisting declined post-KAS; however, disparity remains.

What is the impact of human leukocyte antigen mismatching on graft survival and mortality in renal transplantation? A meta-analysis of 23 cohort studies involving 486,608 recipients

Background

The magnitude effects of human leukocyte antigen (HLA) mismatching on post-transplant outcomes of kidney transplantation remain controversial. We aim to quantitatively assess the associations of HLA mismatching with graft survival and mortality in adult kidney transplantation.

Methods

We searched PubMed, EMBASE and the Cochrane Library from their inception to December, 2016. Priori clinical outcomes were overall graft failure, death-censored graft failure and all-cause mortality.

Results

A total of 23 cohort studies covering 486,608 recipients were selected. HLA per mismatch was significant associated with increased risks of overall graft failure (hazard ratio (HR), 1.06; 95% confidence interval (CI), 1.05–1.07), death-censored graft failure (HR: 1.09; 95% CI 1.06–1.12) and all-cause mortality (HR: 1.04; 95% CI: 1.02–1.07). Besides, HLA-DR mismatches were significant associated with worse overall graft survival (HR: 1.12, 95% CI: 1.05–1.21). For HLA-A locus, the association was insignificant (HR: 1.06; 95% CI: 0.98–1.14). We observed no significant association between HLA-B locus and overall graft failure (HR: 1.01; 95% CI: 0.90–1.15). In subgroup analyses, we found recipient sample size and ethnicity maybe the potential sources of heterogeneity.

Conclusions

HLA mismatching was still a critical prognostic factor that affects graft and recipient survival. HLA-DR mismatching has a substantial impact on recipient’s graft survival. HLA-A mismatching has minor but insignificant impact on graft survival outcomes.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-0908-3) contains supplementary material, which is available to authorized users.

New Kidney Allocation System Associated With Increased Rates Of Transplants Among Black And Hispanic Patients

Before the 2014 implementation of a new kidney allocation system by the United Network for Organ Sharing, white patients were more likely than black or Hispanic patients to receive a kidney transplant. To determine the effect of the new allocation system on these disparities, we examined data for 179,071 transplant waiting list events in the period June 2013-September 2016, and we calculated monthly transplantation rates (34,133 patients actually received transplants). Implementation of the new system was associated with a narrowing of the disparities in the average monthly transplantation rates by 0.29 percentage point for blacks compared to whites and by 0.24 percentage point for Hispanics compared to whites, which resulted in both disparities becoming nonsignificant after implementation of the new system.

Association of Race and Ethnicity With Live Donor Kidney Transplantation in the United States From 1995 to 2014

IMPORTANCE

Over the past 2 decades, there has been increased attention and effort to reduce disparities in live donor kidney transplantation (LDKT) for black, Hispanic, and Asian patients with end-stage kidney disease. The goal of this study was to investigate whether these efforts have been successful.

OBJECTIVE

To estimate changes over time in racial/ethnic disparities in LDKT in the United States, accounting for differences in death and deceased donor kidney transplantation.

DESIGN, SETTING, AND PARTICIPANTS

A secondary analysis of a prospectively maintained cohort study conducted in the United States of 453 162 adult first-time kidney transplantation candidates included in the Scientific Registry of Transplant Recipients between January 1, 1995, and December 31, 2014, with follow-up through December 31, 2016.

EXPOSURES

Race/ethnicity.

MAIN OUTCOMES AND MEASURES

The primary study outcome was time to LDKT. Multivariable Cox proportional hazards and competing risk models were constructed to assess changes in racial/ethnic disparities in LDKT among adults on the deceased donor kidney transplantation waiting list and interaction terms were used to test the statistical significance of temporal changes in racial/ethnic differences in receipt of LDKT. The adjusted subhazard ratios are estimates derived from the multivariable competing risk models. Data were categorized into 5-year increments (1995-1999, 2000-2004, 2005-2009, 2010-2014) to allow for an adequate sample size in each analytical cell.

RESULTS

Among 453 162 adult kidney transplantation candidates (mean [SD] age, 50.9 [13.1] years; 39% were women; 48% were white; 30%, black; 16%, Hispanic; and 6%, Asian), 59 516 (13.1%) received LDKT. Overall, there were 39 509 LDKTs among white patients, 8926 among black patients, 8357 among Hispanic patients, and 2724 among Asian patients. In 1995, the cumulative incidence of LDKT at 2 years after appearing on the waiting list was 7.0% among white patients, 3.4% among black patients, 6.8% among Hispanic patients, and 5.1% among Asian patients. In 2014, the cumulative incidence of LDKT was 11.4% among white patients, 2.9% among black patients, 5.9% among Hispanic patients, and 5.6% among Asian patients. From 1995-1999 to 2010-2014, racial/ethnic disparities in the receipt of LDKT increased (P < .001 for all statistical interaction terms in adjusted models comparing white patients vs black, Hispanic, and Asian patients). In 1995-1999, compared with receipt of LDKT among white patients, the adjusted subhazard ratio was 0.45 (95% CI, 0.42-0.48) among black patients, 0.83 (95% CI, 0.77-0.88) among Hispanic patients, and 0.56 (95% CI, 0.50-0.63) among Asian patients. In 2010-2014, compared with receipt of LDKT among white patients, the adjusted subhazard ratio was 0.27 (95% CI, 0.26-0.28) among black patients, 0.52 (95% CI, 0.50-0.54) among Hispanic patients, and 0.42 (95% CI, 0.39-0.45) among Asian patients.

CONCLUSIONS AND RELEVANCE

Among adult first-time kidney transplantation candidates in the United States who were added to the deceased donor kidney transplantation waiting list between 1995 and 2014, disparities in the receipt of live donor kidney transplantation increased from 1995-1999 to 2010-2014. These findings suggest that national strategies for addressing disparities in receipt of live donor kidney transplantation should be revisited.

The impact of human leukocyte antigen mismatching on graft survival and mortality in adult renal transplantation: A protocol for a systematic review and meta-analysis

BACKGROUND

Human leukocyte antigen (HLA) was important biological barrier to a successful transplantation. Quantitative evaluations of the effect of HLA mismatching on heart, liver, umbilical cord blood, and hematopoietic stem cell transplantation, have previously been reported. In new era of immunosuppression, the reported magnitude effect of HLA mismatching on survival outcomes of kidney transplantation was controversial. In addition, the current kidney allocation guideline recommendations in different countries were inconsistent in term of HLA mismatching. We undertake this study to conduct a systematic review and meta-analysis to assess the magnitude effect of HLA mismatching in adult kidney transplantation, with a particular focus on graft survival and mortality.

METHODS

The present systematic review and meta-analysis protocol was conducted following the Meta-analysis of Observational Studies in Epidemiology protocol (MOOSE-P) and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis protocol (PRISMA-P). PubMed, EMBASE, Cochrane library Database will be searched without language restriction. Studies fulfill the following criteria will be eligible: included study cohorts comprising adult recipients; reported the association between HLA mismatching (per mismatches or HLA-A, -B, -DR mismatches) and posttransplant survival outcomes; provided effect estimates of hazard ratios (HRs) with 95% confidence interval (CIs). The incidence of measured outcomes was defined according to the European Renal Best Practice Transplantation Guidelines and Kidney Disease: Improving Global Outcomes Guidelines.

RESULTS

This study will quantitatively assess the association of HLA per mismatches, DR-antigen mismatches, A-antigen mismatches, and B-antigen mismatches with survival outcomes of overall graft failure, death-censored graft failure, all-cause mortality, and mortality with a functioning graft.

CONCLUSION

This study will determine the issues on what extent HLA compatibility influenced recipient and graft survival and which HLA antigen plays a more important role in kidney transplantation.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017071894.

Influence of HLA Matching on the Efficacy of Allogeneic Mesenchymal Stromal Cell Therapies for Osteoarthritis and Degenerative Disc Disease

BACKGROUND

The necessity for more effective therapies for chronic osteoarticular diseases has led to the development of treatments based on mesenchymal stem cells (MSCs), the natural precursors of musculoskeletal tissue. Treatments with autologous MSCs yielded excellent results, with nearly 70% improvement of pain and disability in osteoarthritis and degenerative disc disease. Using allogeneic MSCs is logistically more convenient and would widen the pool of eligible patients, but potential immune rejection should be considered. In this context, MSCs are purportedly immune evasive and better tolerated than other cell types.

METHODS

We used samples collected during the performance of 2 randomized clinical trials using allogeneic bone marrow MSCs for treatment of osteoarthritis (NCT01586312) and degenerative disc disease (NCT01860417). Serum samples were used to determine anti-HLA antibodies, whereas either blood or MSC samples were used for HLA typing of recipients and donors, respectively. Algofunctional indexes were used as indicators of clinical evolution, and the correlation between the number of donor-host HLA mismatches and the efficacy of treatment was determined.

RESULTS

Immune response was weak and transient, with reactivity decaying during the first year. Consistently, better donor-recipient HLA matching did not enhance efficacy.

CONCLUSIONS

This lack of reactivity is presumably due to the cooperation of 2 factors, (1) downregulation of the host immune responses by the transplanted MSCs and (2) effective insulation of these cells inside the articular cavity or the intervertebral disc, respectively. Interestingly, better HLA matching did not enhance efficacy. These observations have medical relevance as they support the clinical use of allogeneic cells, at least as a single-dose administration. Multiple-dose applications will require further research to exclude possible sensitization.

The Risk of Transplant Failure With HLA Mismatch in First Adult Kidney Allografts From Deceased Donors

BACKGROUND

Since the beginning of the technology, there has been active debate about the role of human leucocyte antigen (HLA) matching in kidney allograft survival. Recent studies have reported diminishing importance of HLA matching, which have, in turn, been challenged by reports that suggest the continuing importance of these loci. Given the controversies, we examined the effect of HLA compatibility on kidney allograft survival by studying all first adult kidney transplants in the United States from a deceased donor.

METHODS

Using the United Network for Organ Sharing data, we identified first deceased donor kidney transplants between October 1, 1987, and December 31, 2013. Recipients were classified by their number of HLA mismatches. Cox multivariate regression analyses adjusting for recipient and donor transplant characteristics were performed to determine the impact of HLA compatibility on kidney allograft survival.

RESULTS

Study cohort included 189 141 first adult kidney alone transplants, with a total of 994 558 years of kidney allograft follow-up time. Analyses adjusted for recipient and donor characteristics demonstrated a 13% higher risk (hazard ratio, 1.13; 95% confidence interval, 1.06-1.21) with 1 mismatch and a 64% higher risk (hazard ratio, 1.64, 95% confidence interval, 1.56-1.73) with 6 mismatches. Dividing the mismatch categories into 27 ordered permutations, and testing their 57 within mismatch category differences, demonstrated that all but 1 were equal, independent of locus.

CONCLUSIONS

A significant linear relationship of hazard ratios was associated with HLA mismatch and affects allograft survival even during the recent periods of increasing success in renal transplantation.

HLA Mismatching Strategies for Solid Organ Transplantation - A Balancing Act

HLA matching provides numerous benefits in organ transplantation including better graft function, fewer rejection episodes, longer graft survival, and the possibility of reduced immunosuppression. Mismatches are attended by more frequent rejection episodes that require increased immunosuppression that, in turn, can increase the risk of infection and malignancy. HLA mismatches also incur the risk of sensitization, which can reduce the opportunity and increase waiting time for a subsequent transplant. However, other factors such as donor age, donor type, and immunosuppression protocol, can affect the benefit derived from matching. Furthermore, finding a well-matched donor may not be possible for all patients and usually prolongs waiting time. Strategies to optimize transplantation for patients without a well-matched donor should take into account the immunologic barrier represented by different mismatches: what are the least immunogenic mismatches considering the patient’s HLA phenotype; should repeated mismatches be avoided; is the patient sensitized to HLA and, if so, what are the strengths of the patient’s antibodies? This information can then be used to define the HLA type of an immunologically optimal donor and the probability of such a donor occurring. A probability that is considered to be too low may require expanding the donor population through paired donation or modifying what is acceptable, which may require employing treatment to overcome immunologic barriers such as increased immunosuppression or desensitization. Thus, transplantation must strike a balance between the risk associated with waiting for the optimal donor and the risk associated with a less than optimal donor.

Referral for Kidney Transplantation and Indicators of Quality of Dialysis Care: A Cross-sectional Study

BACKGROUND

Dialysis facility performance measures to improve access to kidney transplantation are being considered. Referral of patients for kidney transplantation evaluation by the dialysis facility is one potential indicator, but limited data exist to evaluate whether referral is associated with existing dialysis facility quality indicators.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

12,926 incident (July 2005 to September 2011) adult (aged 18-69 years) patients treated at 241 dialysis facilities with complete quality indicator information from US national registry data linked to transplantation referral data from all 3 Georgia kidney transplantation centers.

FACTORS

Facility performance on dialysis quality indicators (high, intermediate, and low tertiles).

OUTCOME

Percentages of patients referred within 1 year of dialysis therapy initiation at dialysis facility.

RESULTS

Overall, a median of 25.4% of patients were referred for kidney transplantation within 1 year of dialysis therapy initiation. Higher facility-level referral was associated with better performance with respect to standardized transplantation ratio (high, 28.6%; intermediate, 25.1%; and low, 22.9%; P=0.001) and percentage waitlisted (high, 30.7%; intermediate, 26.8%; and low, 19.2%; P<0.001). Facility-level referral was not associated with indicators of quality of care associated with dialysis therapy initiation, including percentage of incident patients being informed of transplantation options. For most non-transplantation-related indicators of high-quality care, including those capturing mortality, morbidity, and anemia management, better performance was not associated with higher facility-level transplantation referral.

LIMITATIONS

Potential ecologic fallacy and residual confounding.

CONCLUSIONS

Transplantation referral among patients at dialysis facilities does not appear to be associated with overall quality of dialysis care at the facility. Quality indicators related to kidney transplantation were positively associated with, but not entirely correspondent with, higher percentages of patients referred for kidney transplantation evaluation from dialysis facilities. These results suggest that facility-level referral, which is within the control of the dialysis facility, may provide information about the quality of dialysis care beyond current indicators.

Reduced Racial Disparity in Kidney Transplant Outcomes in the United States from 1990 to 2012

Earlier studies reported inferior outcomes among black compared with white kidney transplant (KT) recipients. We examined whether this disparity improved in recent decades. Using the Scientific Registry of Transplant Recipients and Cox regression models, we compared all-cause graft loss among 63,910 black and 145,482 white adults who received a first-time live donor KT (LDKT) or deceased donor KT (DDKT) in 1990-2012. Over this period, 5-year graft loss after DDKT improved from 51.4% to 30.6% for blacks and from 37.3% to 25.0% for whites; 5-year graft loss after LDKT improved from 37.4% to 22.2% for blacks and from 20.8% to 13.9% for whites. Among DDKT recipients in the earliest cohort, blacks were 39% more likely than whites to experience 5-year graft loss (adjusted hazard ratio [aHR], 1.39; 95% confidence interval [95% CI], 1.32 to 1.47; P<0.001), but this disparity narrowed in the most recent cohort (aHR, 1.10; 95% CI, 1.03 to 1.18; P=0.01). Among LDKT recipients in the earliest cohort, blacks were 53% more likely than whites to experience 5-year graft loss (aHR, 1.53; 95% CI, 1.27 to 1.83; P<0.001), but this disparity also narrowed in the most recent cohort (aHR, 1.37; 95% CI, 1.17 to 1.61; P<0.001). Analyses revealed no statistically significant differences in 1-year or 3-year graft loss after LDKT or DDKT in the most recent cohorts. Our findings of reduced disparities over the last 22 years driven by more markedly improved outcomes for blacks may encourage nephrologists and patients to aggressively promote access to transplantation in the black community.

Racial disparities in reaching the renal transplant waitlist: is geography as important as race?

BACKGROUND

In the United States, African Americans and whites differ in access to the deceased donor renal transplant waitlist. The extent to which racial disparities in waitlisting differ between United Network for Organ Sharing (UNOS) regions is understudied.

METHODS

The US Renal Data System (USRDS) was linked with US census data to examine time from dialysis initiation to waitlisting for whites (n = 188,410) and African Americans (n = 144,335) using Cox proportional hazards across 11 UNOS regions, adjusting for potentially confounding individual, neighborhood, and state characteristics.

RESULTS

Likelihood of waitlisting varies significantly by UNOS region, overall and by race. Additionally, African Americans face significantly lower likelihood of waitlisting compared to whites in all but two regions (1 and 6). Overall, 39% of African Americans with ESRD reside in Regions 3 and 4--regions with a large racial disparity and where African Americans comprise a large proportion of the ESRD population. In these regions, the African American-white disparity is an important contributor to their overall regional disparity.

CONCLUSIONS

Race remains an important factor in time to transplant waitlist in the United States. Race contributes to overall regional disparities; however, the importance of race varies by UNOS region.

Comparison of quality-of-care measures in U.S. patients with end-stage renal disease secondary to lupus nephritis vs. other causes

BACKGROUND

Patients with end-stage renal disease (ESRD) due to lupus nephritis (LN-ESRD) may be followed by multiple providers (nephrologists and rheumatologists) and have greater opportunities to receive recommended ESRD-related care. We aimed to examine whether LN-ESRD patients have better quality of ESRD care compared to other ESRD patients.

METHODS

Among incident patients (7/05-9/11) with ESRD due to LN (n = 6,594) vs. other causes (n = 617,758), identified using a national surveillance cohort (United States Renal Data System), we determined the association between attributed cause of ESRD and quality-of-care measures (pre-ESRD nephrology care, placement on the deceased donor kidney transplant waitlist, and placement of permanent vascular access). Multivariable logistic and Cox proportional hazards models were used to estimate adjusted odds ratios (ORs) and hazard ratios (HRs).

RESULTS

LN-ESRD patients were more likely than other ESRD patients to receive pre-ESRD care (71% vs. 66%; OR = 1.68, 95% CI 1.57-1.78) and be placed on the transplant waitlist in the first year (206 vs. 86 per 1000 patient-years; HR = 1.42, 95% CI 1.34-1.52). However, only 24% had a permanent vascular access (fistula or graft) in place at dialysis start (vs. 36%; OR = 0.63, 95% CI 0.59-0.67).

CONCLUSIONS

LN-ESRD patients are more likely to receive pre-ESRD care and have better access to transplant, but are less likely to have a permanent vascular access for dialysis, than other ESRD patients. Further studies are warranted to examine barriers to permanent vascular access placement, as well as morbidity and mortality associated with temporary access, in patients with LN-ESRD.

The role of minority geographic distribution in waiting time for deceased donor kidney transplantation

In the US, African Americans and other minority groups have longer wait times to deceased donor kidney transplantation than Caucasians. To date, the role of geographic distribution of racial and ethnic groups as a determinant of wait times has not been fully elucidated. Using the Scientific Registry of Transplant Recipients database, all registrants for kidney transplant between 2004 and 2007 (n=126,094) were analyzed from time of waitlisting until nonzero antigen mismatched deceased donor kidney transplant. Nationally, deceased donor transplantation occurred at a lower rate for African Americans (hazard ratio [HR] 0.85, confidence interval [CI] 0.83-0.87), Hispanics (HR 0.68, CI 0.66-0.70), Asians/Pacific Islanders (HR 0.77, CI 0.73-0.80) and Other minority groups (HR 0.74, CI 0.69-0.81) compared to Caucasians. Multivariate modeling for age, gender, cause of end-stage renal disease, ABO type, panel reactive antibody, HLA-DR frequency, expanded criteria donor status and prior kidney donation only partially accounted for this difference. Adjusting for these variables and organ procurement organization of listing, African Americans (HR 1.03, CI 1.00-1.06), Hispanics (HR 1.15, CI 1.10-1.19), Asians/Pacific Islanders (HR 1.36, CI 1.30-1.43) and Other minority groups (HR 1.00, CI 0.92-1.09) were transplanted at similar or higher rates than Caucasians. Our findings show that geographic location of waitlisted candidates is the most important contributor to racial disparities in waiting times for deceased donor kidney transplantation.

The RaDIANT community study protocol: community-based participatory research for reducing disparities in access to kidney transplantation

BACKGROUND

The Southeastern United States has the lowest kidney transplant rates in the nation, and racial disparities in kidney transplant access are concentrated in this region. The Southeastern Kidney Transplant Coalition (SEKTC) of Georgia, North Carolina, and South Carolina is an academic and community partnership that was formed with the mission to improve access to kidney transplantation and reduce disparities among African American (AA) end stage renal disease (ESRD) patients in the Southeastern United States.

METHODS/DESIGN

We describe the community-based participatory research (CBPR) process utilized in planning the Reducing Disparities In Access to kidNey Transplantation (RaDIANT) Community Study, a trial developed by the SEKTC to reduce health disparities in access to kidney transplantation among AA ESRD patients in Georgia, the state with the lowest kidney transplant rates in the nation. The SEKTC Coalition conducted a needs assessment of the ESRD population in the Southeast and used results to develop a multicomponent, dialysis facility-randomized, quality improvement intervention to improve transplant access among dialysis facilities in GA. A total of 134 dialysis facilities are randomized to receive either: (1) standard of care or "usual" transplant education, or (2) the multicomponent intervention consisting of transplant education and engagement activities targeting dialysis facility leadership, staff, and patients within dialysis facilities. The primary outcome is change in facility-level referral for kidney transplantation from baseline to 12 months; the secondary outcome is reduction in racial disparity in transplant referral.

DISCUSSION

The RaDIANT Community Study aims to improve equity in access to kidney transplantation for ESRD patients in the Southeast.

TRIAL REGISTRATION

Clinicaltrials.gov number NCT02092727.

Patient selection and volume in the era surrounding implementation of Medicare conditions of participation for transplant programs

OBJECTIVE

To evaluate evidence of practice changes affecting kidney transplant program volumes, and donor, recipient and candidate selection in the era surrounding the introduction of Centers for Medicare and Medicaid Services (CMS) conditions of participation (CoPs) for organ transplant programs.

DATA

Scientific Registry of Transplant Recipients; CMS ESRD and Medicare claims databases.

DESIGN

Retrospective analysis of national registry data.

METHODS

A Cox proportional hazards model of 1-year graft survival was used to derive risks associated with deceased-donor kidney transplants performed from 2001 to 2010.

FINDINGS

Among programs with ongoing noncompliance with the CoPs, kidney transplant volumes declined by 38 percent (n = 766) from 2006 to 2011, including a 55 percent drop in expanded criteria donor transplants. Volume increased by 6 percent (n = 638) among programs remaining in compliance. Aggregate risk of 1-year graft failure increased over time due to increasing recipient age and obesity, and longer ESRD duration.

CONCLUSIONS

Although trends in aggregate risk of 1-year kidney graft loss do not indicate that the introduction of the CoPs has systematically reduced opportunities for marginal candidates or that there has been a systematic shift away from utilization of higher risk deceased donor kidneys, total volume and expanded criteria donor utilization decreased overall among programs with ongoing noncompliance.

Accountability for end-stage organ care: implications of geographic variation in access to kidney transplantation

BACKGROUND

The provision of effective surgical care for end-stage renal disease (ESRD) requires efficient evaluation and transplantation. Prior assessments of transplant access have focused primarily on waitlisted patients rather than the overall populations served by "accountable" providers of transplant services.

METHODS

Novel transplant referral regions (TRRs) were defined using United Network for Organ Sharing registry data for 301,092 kidney transplant listings to assign zip codes to "accountable" transplant programs. Subsequently, risk-adjusted observed to expected (O:E) rates of listing and transplant procedures were calculated for each TRR. Finally, the impact of variation in TRR listing and transplant rates on mortality was assessed for ESRD patients <60 years old diagnosed between 2000 and 2008.

RESULTS

In total, 113 TRRs were defined, 51% of which included >1 transplant center. The likelihood of being evaluated and listed for transplant varied significantly between TRRs (risk-adjusted O:E, 0.58-1.95). Variation was greater for the overall transplant rate (0.62-2.19), living donor transplantation (0.36-3.08), and donation after cardiac death transplant (0-15.4) than for standard criteria donors (0.64-2.86). Mortality was decreased for ESRD patients living in TRRs in the highest tertile of listings (hazard ratio, 0.89; P < .0001) and transplantation (0.90; P < .0001).

CONCLUSION

Residence in a TRR with care delivery systems that increase access to transplant services is associated with significant, risk-adjusted decreases in ESRD-related mortality. Transplant centers should continue to focus on improving access to care within the communities they serve.

Racial and ethnic differences in pediatric access to preemptive kidney transplantation in the United States

Preemptive kidney transplantation is the optimal treatment for pediatric end stage renal disease patients to avoid increased morbidity and mortality associated with dialysis. It is unknown how race/ethnicity and poverty influence preemptive transplant access in pediatric. We examined the incidence of living donor or deceased donor preemptive transplantation among all black, white, and Hispanic children (<18 years) in the United States Renal Data System from 2000 to 2009. Adjusted risk ratios for preemptive transplant were calculated using multivariable-adjusted models and examined across health insurance and neighborhood poverty levels. Among 8,053 patients, 1117 (13.9%) received a preemptive transplant (66.9% from LD, 33.1% from DD). In multivariable analyses, there were significant racial/ethnic disparities in access to LD preemptive transplant where blacks were 66% (RR = 0.34; 95% CI: 0.28-0.43) and Hispanics 52% (RR = 0.48; 95% CI: 0.35-0.67) less likely to receive a LD preemptive transplant versus whites. Blacks were 22% less likely to receive a DD preemptive transplant versus whites (RR = 0.78, 95% CI: 0.57-1.05), although results were not statistically significant. Future efforts to promote equity in preemptive transplant should address the critical issues of improving access to pre-ESRD nephrology care and overcoming barriers in living donation, including obstacles partially driven by poverty.

Kidney, pancreas and liver allocation and distribution in the United States

Kidney transplant and liver transplant are the treatments of choice for patients with end-stage renal disease and end-stage liver disease, respectively. Pancreas transplant is most commonly performed along with kidney transplant in diabetic end-stage renal disease patients. Despite a steady increase in the numbers of kidney and liver transplants performed each year in the United States, a significant shortage of kidneys and livers available for transplant remains. Organ allocation is the process the Organ Procurement and Transplantation Network (OPTN) uses to determine which candidates are offered which deceased donor organs. OPTN is charged with ensuring the effectiveness, efficiency and equity of organ sharing in the national system of organ allocation. The policy has changed incrementally over time in efforts to optimize allocation to meet these often competing goals. This review describes the history, current status and future direction of policies regarding the allocation of abdominal organs for transplant, namely the kidney, liver and pancreas, in the United States.

Who should be prioritized for renal transplantation?: Analysis of key stakeholder preferences using discrete choice experiments

Background

Policies for allocating deceased donor kidneys have recently shifted from allocation based on Human Leucocyte Antigen (HLA) tissue matching in the UK and USA. Newer allocation algorithms incorporate waiting time as a primary factor, and in the UK, young adults are also favoured. However, there is little contemporary UK research on the views of stakeholders in the transplant process to inform future allocation policy. This research project aimed to address this issue.

Methods

Discrete Choice Experiment (DCE) questionnaires were used to establish priorities for kidney transplantation among different stakeholder groups in the UK. Questionnaires were targeted at patients, carers, donors / relatives of deceased donors, and healthcare professionals. Attributes considered included: waiting time; donor-recipient HLA match; whether a recipient had dependents; diseases affecting life expectancy; and diseases affecting quality of life.

Results

Responses were obtained from 908 patients (including 98 ethnic minorities); 41 carers; 48 donors / relatives of deceased donors; and 113 healthcare professionals. The patient group demonstrated statistically different preferences for every attribute (i.e. significantly different from zero) so implying that changes in given attributes affected preferences, except when prioritizing those with no rather than moderate diseases affecting quality of life. The attributes valued highly related to waiting time, tissue match, prioritizing those with dependents, and prioritizing those with moderate rather than severe diseases affecting life expectancy. Some preferences differed between healthcare professionals and patients, and ethnic minority and non-ethnic minority patients. Only non-ethnic minority patients and healthcare professionals clearly prioritized those with better tissue matches.

Conclusions

Our econometric results are broadly supportive of the 2006 shift in UK transplant policy which emphasized prioritizing the young and long waiters. However, our findings suggest the need for a further review in the light of observed differences in preferences amongst ethnic minorities, and also because those with dependents may be a further priority.

Over ten-year kidney graft survival determinants

Kidney graft survival has been mainly evaluated using an up to 10-year threshold. Instead, in this study our aim was to evaluate predictive variables that impact long-term kidney graft survival (≥10 years). We enrolled 892 patients in our analysis: 638 patients with functioning graft at 10 years PT and 254 patients with graft failure at 10 years PT (considering patient death with a functioning graft <10 years PT as graft failure). Between groups comparisons were done using Mann-Whitney and chi-square test. To determine independent predictive variables for long-term graft survival a multivariate-adjusted logistic regression was performed. Significant predictors of long term graft survival were lower 12-month PT creatinine (OR = 0.26, P < 0.001), lower donor age (OR = 0.98, P = 0.004), shorter time on dialysis (OR = 0.93, P = 0.044), recipient positive CMV IgG (OR = 1.59, P = 0.040), absence of AR episodes (OR = 1.57, P = 0.047), 0 to 1 (versus 2) HLA-B mismatch (OR = 1.80, P = 0.004), and recipients male gender (OR = 1.84, P = 0.005). Our results show that an early KT, younger donor age, and an optimal first year graft function are of paramount importance for long-term graft survival. Measures that address these issues (careful donor selection, preemptive KT, and effective immunosuppressive protocols) are still warranted.

Solid-organ transplantation in older adults: current status and future research

An increasing number of patients older than 65 years are referred for and have access to organ transplantation, and an increasing number of older adults are donating organs. Although short-term outcomes are similar in older versus younger transplant recipients, older donor or recipient age is associated with inferior long-term outcomes. However, age is often a proxy for other factors that might predict poor outcomes more strongly and better identify patients at risk for adverse events. Approaches to transplantation in older adults vary across programs, but despite recent gains in access and the increased use of marginal organs, older patients remain less likely than other groups to receive a transplant, and those who do are highly selected. Moreover, few studies have addressed geriatric issues in transplant patient selection or management, or the implications on health span and disability when patients age to late life with a transplanted organ. This paper summarizes a recent trans-disciplinary workshop held by ASP, in collaboration with NHLBI, NIA, NIAID, NIDDK and AGS, to address issues related to kidney, liver, lung, or heart transplantation in older adults and to propose a research agenda in these areas.

Review of ethnic disparities in access to renal transplantation

Renal transplantation is the gold standard treatment for patients with end-stage renal disease and is associated with several advantages over dialysis, including increased quality of life, reduced morbidity and mortality, and lower healthcare costs. Barring the constraints of a limited organ supply, the goals of the patient care should focus on attaining renal transplantation while minimizing, or even eliminating, time spent on dialysis. Disparities in access to renal transplantation between African Americans and Caucasians have been extensively documented, with African Americans having significantly poorer access. There is a growing corpus of literature examining the determinants of reduced access among other racial ethnic minority groups, including Hispanics. These determinants include patient and physician preference, socioeconomic status, insurance type, patient education, and immunologic factors. We review these determinants in access to renal transplantation in the United States among all races and ethnicities.