Renal transplantation in black Americans

Immunologic Benefits of 0-antigen Mismatched Transplants: No Added Boost for Racial and Ethnic Minorities

Background

Systemic barriers to posttransplant care, including access to immunosuppressant medications, contribute to higher rates of kidney transplant failure in racial minorities. Matching donor and recipient HLA alleles reduce allorecognition, easing reliance on immunosuppression. We hypothesize that 0-antigen mismatch transplants may provide stronger protection against graft loss in racial minorities.

Methods

We compared adult, single-organ, deceased-donor kidney transplants in the United States from 2007 to 2016 by degree of HLA mismatch (0- versus ≥1-antigen mismatch). We examined time-to-allograft failure, with death as a competing event, using multivariable Weibull models, stratified by recipient race (White versus non-White), and evaluated the interaction between mismatch and recipient race. We used Kaplan-Meier imputation to account for competing risk of death.

Results

We analyzed 102 114 transplants (median follow-up, 5.6 y; 16 862 graft losses, 18 994 deaths). Zero-antigen mismatch was associated with improved allograft survival (adjusted subdistribution hazard ratio [sHR] 0.80; 95% confidence interval [CI], 0.75-0.85). When stratified by recipient race, the effect of 0-antigen mismatch was more pronounced in White (unadjusted sHR 0.78; 95% CI, 0.72-0.83) versus non-White recipients (sHR 0.88; 95% CI, 0.79-0.99; interaction P = 0.04). The differential effect was attenuated after adjusting for covariates (sHR 0.78; 95% CI, 0.73-0.84 versus sHR 0.87; 95% CI, 0.77-0.98; interaction P = 0.10).

Conclusions

Zero-antigen mismatch transplants conferred a 20% risk reduction in allograft loss, which was similar between non-White and White recipients. This may reflect an increased degree of mismatch at other HLA alleles and non-HLA alleles in non-White recipients or because of the extent of systemic barriers to healthcare borne by minority recipients.

Maximizing matching, equity and survival in kidney transplantation using molecular HLA immunogenicity quantitation

HLA matching improves long-term outcomes of kidney transplantation, yet implementation challenges persist, particularly within the African American (Black) patient demographic due to donor scarcity. Consequently, kidney survival rates among Black patients significantly lag behind those of other racial groups. A refined matching scheme holds promise for improving kidney survival, with prioritized matching for Black patients potentially bolstering rates of HLA-matched transplants. To facilitate quantity, quality and equity in kidney transplants, we propose two matching algorithms based on quantification of HLA immunogenicity using the hydrophobic mismatch score (HMS) for prospective transplants. We mined the national transplant patient database (SRTR) for a diverse group of donors and recipients with known racial backgrounds. Additionally, we use novel methods to infer survival assessment in the simulated transplants generated by our matching algorithms, in the absence of actual target outcomes, utilizing modified unsupervised clustering techniques. Our allocation algorithms demonstrated the ability to match 87.7% of Black and 86.1% of White recipients under the HLA immunogenicity threshold of 10. Notably, at the lowest HMS threshold of 0, 4.4% of Black and 12.1% of White recipients were matched, a marked increase from the 1.8% and 6.6% matched under the prevailing allocation scheme. Furthermore, our allocation algorithms yielded similar or improved survival rates, as illustrated by Kaplan-Meier (KM) curves, and enhanced survival prediction accuracy, evidenced by C-indices and Integrated Brier Scores.

Racial Disparities in Hospitalization Rates During Long-Term Follow-Up After Deceased-Donor Kidney Transplantation

OBJECTIVE

To compare hospitalization rates between African American (AA) and European American (EA) deceased-donor (DD) kidney transplant (KT) recipients during over a10-year period.

METHOD

Data from the Scientific Registry of Transplant Recipients and social determinants of health (SDoH), measured by the Social Deprivation Index, were used. Hospitalization rates were estimated for kidney recipients from AA and EA DDs who had one kidney transplanted into an AA and one into an EA, leading to four donor/recipient pairs (DRPs): AA/AA, AA/EA, EA/AA, and EA/EA. Poisson-Gamma models were fitted to assess post-transplant hospitalizations.

RESULT

Unadjusted hospitalization rates (95% confidence interval) were higher among all DRP involving AA, 131.1 (122.5, 140.3), 134.8 (126.3, 143.8), and 102.4 (98.9, 106.0) for AA/AA, AA/EA, and EA/AA, respectively, compared to 97.1 (93.7, 100.6) per 1000 post-transplant person-years for EA/EA pairs. Multivariable analysis showed u-shaped relationships across SDoH levels within each DRP, but findings varied depending on recipients' race, i.e., AA recipients in areas with the worst SDoH had higher hospitalization rates. However, EA recipients in areas with the best SDoH had higher hospitalization rates than their counterparts.

CONCLUSIONS

Relationship between healthcare utilization and SDoH depends on DRP, with higher hospitalization rates among AA recipients living in areas with the worst SDoH and among EA recipients in areas with the best SDoH profiles. SDoH plays an important role in driving disparities in hospitalizations after kidney transplantation.

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.

Multilevel Intervention to Improve Racial Equity in Access to Kidney Transplant

BACKGROUND

African Americans (AAs) have reduced access to kidney transplant (KTX). Our center undertook a multilevel quality improvement endeavor to address KTX access barriers, focused on vulnerable populations. This program included dialysis center patient/staff education, embedding telehealth services across South Carolina, partnering with community providers to facilitate testing/procedures, and increased use of high-risk donors.

STUDY DESIGN

This was a time series analysis from 2017 to 2021 using autoregression to assess trends in equitable access to KTX for AAs. Equity was measured using a modified version of the Kidney Transplant Equity Index (KTEI), defined as the proportion of AAs in South Carolina with end-stage kidney disease (ESKD) vs the proportion of AAs initiating evaluation, completing evaluation, waitlisting, and undergoing KTX. A KTEI of 1.00 is considered complete equity; a KTEI of <1.00 is indicative of disparity.

RESULTS

From January 2017 to September 2021, 11,487 ESKD patients (64.7% AA) were referred, 6,748 initiated an evaluation (62.8% AA), 4,109 completed evaluation (59.7% AA), 2,762 were waitlisted (60.0% AA), and 1,229 underwent KTX (55.3% AA). The KTEI for KTX demonstrated significant improvements in equity. The KTEI for initiated evaluations was 0.89 in 2017, improving to 1.00 in 2021 (p = 0.0045). Completed evaluation KTEI improved from 0.85 to 0.95 (p = 0.0230), while waitlist addition KTEI improved from 0.83 to 0.96 (p = 0.0072). The KTEI for KTX also improved from 0.76 to 0.91, which did not reach statistical significance (p = 0.0657).

CONCLUSIONS

A multilevel intervention focused on improving access to vulnerable populations was significantly associated with reduced disparities for AAs.

MyKidneyCoach, Patient Activation, and Clinical Outcomes in Diverse Kidney Transplant Recipients: A Randomized Control Pilot Trial

Kidney transplant (KT) recipients who are not actively engaged in their care and lack self-management skills have poor transplant outcomes, which are disproportionately observed among Black KT recipients. This pilot study aimed to determine whether the MyKidneyCoach app, an mHealth intervention that provides self-management monitoring and coaching, improved patient activation, engagement, and nutritional behaviors in a diverse KT population.

Methods

This was a randomized, age-stratified, parallel-group, attention-control, pilot study in post-KT patients. Participants were randomized into the attention-control with access to MyKidneyCoach for education and self-management (n = 9) or the intervention with additional tailored nurse coaching (n = 7). Feasibility, acceptability, and clinical outcomes were assessed.

Results

The acceptability of MyKidneyCoach by System Usability Scale was 67.5 (95% confidence interval [CI], 59.1-75.9). Completion rates based on actively using MyKidneyCoach were 81% (95% CI, 57%-93%) and study retention rate of 73%. Patient activation measure significantly increased overall by a mean of 11 points (95% CI, 3.2-18.8). Additionally, Black patients (n = 7) had higher nutrition self-efficacy scores of 80.5 (95% CI, 74.4-86.7) compared with 75.6 (95% CI, 71.1-80.1) in non-Black patients (n = 9) but lower patient activation measure scores of 69.3 (95% CI, 56.3-82.3) compared with 71.8 (95% CI, 62.5-81) in non-Black patients after 3 mo.

Conclusions

MyKidneyCoach was easy to use and readily accepted with low attrition, and improvements were demonstrated in patient-reported outcomes. Both Black and non-Black participants using MyKidneyCoach showed improvement in self-management competencies; thus, this intervention may help reduce healthcare inequities in KT.

Pancreas Transplantation in Minorities including Patients with a Type 2 Diabetes Phenotype

Background: Prior to year 2000, the majority of pancreas transplants (PTx) were performed as simultaneous pancreas-kidney transplants (SPKTs) in Caucasian adults with end stage renal failure secondary to type 1 diabetes mellitus (T1DM) who were middle-aged. In the new millennium, improving outcomes have led to expanded recipient selection that includes patients with a type 2 diabetes mellitus (T2DM) phenotype, which excessively affects minority populations. Methods: Using PubMed® to identify appropriate citations, we performed a literature review of PTx in minorities and in patients with a T2DM phenotype. Results: Mid-term outcomes with SPKT in patients with uremia and circulating C-peptide levels (T2DMphenotype) are comparable to those patients with T1DM although there may exist a selection bias in the former group. Excellent outcomes with SPKT suggests that the pathophysiology of T2DM is heterogeneous with elements consisting of both insulin deficiency and resistance related to beta-cell failure. As a result, increasing endogenous insulin (Cp) production following PTx may lead to freedom checking blood sugars or taking insulin, better metabolic counter-regulation, and improvements in quality of life and life expectancy compared to other available treatment options. Experience with solitary PTx for T2DM or in minorities is limited but largely mirrors the trends reported in SPKT. Conclusions: PTx is a viable treatment option in patients with pancreas endocrine failure who are selected appropriately regardless of diabetes type or recipient race. This review will summarize data that unconventional patient populations with insulin-requiring diabetes may gain value from PTx with an emphasis on contemporary experiences and appropriate selection in minorities in the new millennium.

Use of Machine Learning Consensus Clustering to Identify Distinct Subtypes of Black Kidney Transplant Recipients and Associated Outcomes

Importance

Among kidney transplant recipients, Black patients continue to have worse graft function and reduced patient and graft survival. Better understanding of different phenotypes and subgroups of Black kidney transplant recipients may help the transplant community to identify individualized strategies to improve outcomes among these vulnerable groups.

Objective

To cluster Black kidney transplant recipients in the US using an unsupervised machine learning approach.

Design, Setting, and Participants

This cohort study performed consensus cluster analysis based on recipient-, donor-, and transplant-related characteristics in Black kidney transplant recipients in the US from January 1, 2015, to December 31, 2019, in the Organ Procurement and Transplantation Network/United Network for Organ Sharing database. Each cluster's key characteristics were identified using the standardized mean difference, and subsequently the posttransplant outcomes were compared among the clusters. Data were analyzed from June 9 to July 17, 2021.

Exposure

Machine learning consensus clustering approach.

Main Outcomes and Measures

Death-censored graft failure, patient death within 3 years after kidney transplant, and allograft rejection within 1 year after kidney transplant.

Results

Consensus cluster analysis was performed for 22 687 Black kidney transplant recipients (mean [SD] age, 51.4 [12.6] years; 13 635 men [60%]), and 4 distinct clusters that best represented their clinical characteristics were identified. Cluster 1 was characterized by highly sensitized recipients of deceased donor kidney retransplants; cluster 2, by recipients of living donor kidney transplants with no or short prior dialysis; cluster 3, by young recipients with hypertension and without diabetes who received young deceased donor transplants with low kidney donor profile index scores; and cluster 4, by older recipients with diabetes who received kidneys from older donors with high kidney donor profile index scores and extended criteria donors. Cluster 2 had the most favorable outcomes in terms of death-censored graft failure, patient death, and allograft rejection. Compared with cluster 2, all other clusters had a higher risk of death-censored graft failure and death. Higher risk for rejection was found in clusters 1 and 3, but not cluster 4.

Conclusions and Relevance

In this cohort study using an unsupervised machine learning approach, the identification of clinically distinct clusters among Black kidney transplant recipients underscores the need for individualized care strategies to improve outcomes among vulnerable patient groups.

Improving Access to HLA-Matched Kidney Transplants for African American Patients

Introduction

Kidney transplants fail more often in Black than in non-Black (White, non-Black Hispanic, and Asian) recipients. We used the estimated physicochemical immunogenicity for polymorphic amino acids of donor/recipient HLAs to select weakly immunogenic kidney transplants for Black vs. White or non-Black patients.

Methods

OPTN data for 65,040 donor/recipient pairs over a 20-year period were used to calculate the individual physicochemical immunogenicity by hydrophobic, electrostatic and amino acid mismatch scores (HMS, EMS, AMS) and graft-survival outcomes for Black vs. White or vs. non-Black recipients, using Kaplan-Meier survival and Cox regression analyses. Simulations for re-matching recipients with donors were based on race-adjusted HMS thresholds with clinically achievable allocations.

Results

The retrospective median kidney graft survival was 12.0 years in Black vs. 18.6 years in White (6.6-year difference; p>0.001) and 18.4 years in non-Black (6.4-year difference; p>0.01) recipients. Only 0.7% of Blacks received transplants matched at HLA-A/B/DR/DQ (HMS=0) vs. 8.1% in Whites (p<0.001). Among fully matched Blacks (HMS=0), graft survival was 16.1-years and in well-matched Blacks (HMS ≤ 3.0) it was 14.0-years. Whites had 21.6-years survival at HMS ≤ 3.0 and 18.7-years at HMS ≤ 7.0 whereas non-Blacks had 22.0-year at HMS ≤ 3.0 and 18.7-year at HMS ≤ 7.0, confirming that higher HMS thresholds produced excellent survival. Simulation of ABO-compatible donor-recipient pairs using race-adjusted HMS thresholds identified weakly immunogenic matches at HMS=0 for 6.1% Blacks and 18.0% at HMS ≤ 3.0. Despite prioritizing Black patients, non-Black patients could be matched at the same level as in current allocation (47.0% vs 56.5%, at HMS ≤ 7.0).

Conclusions

Race-adjusted HMS (EMS, AMS)-based allocation increased the number of weakly immunogenic donors for Black patients, while still providing excellent options for non-Black recipients.

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

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

Race and sex associations with tacrolimus pharmacokinetics in stable kidney transplant recipients

Study Objective

This study investigated race and sex differences in tacrolimus pharmacokinetics and pharmacodynamics in stable kidney transplant recipients.

Design and Setting

A cross‐sectional, open‐label, single center, 12‐h pharmacokinetic‐pharmacodynamic study was conducted. Tacrolimus pharmacokinetic parameters included area under the concentration‐time curve (AUC_0–12), AUC_0–4, 12‐h troughs (C_12 h), maximum concentrations (C_max), oral clearance (Cl), with dose‐normalized AUC_0–12, troughs, and C_max with standardized adverse effect scores. Statistical models were used to analyze end points with individual covariate‐adjustment including clinical factors, genotypic variants CYP3A5*3, CYP3A5*6, CYP3A5*7(CYP3A5*3*6*7) metabolic composite, and ATP binding cassette gene subfamily B member 1 (ABCB1) polymorphisms.

Patients

65 stable, female and male, Black and White kidney transplant recipients receiving tacrolimus and mycophenolic acid ≥6 months post‐transplant were evaluated.

Measurements and Main Results

Black recipients exhibited higher tacrolimus AUC_0–12 (Race: p = 0.005), lower AUC* (Race: p < 0.001; Race × Sex: p = 0.068), and higher Cl (Race: p < 0.001; Sex: p = 0.066). Greater cumulative (Sex: p < 0.001; Race × Sex: p = 0.014), neurologic (Sex: p = 0.021; Race × Sex: p = 0.005), and aesthetic (Sex: p = 0.002) adverse effects were found in females, with highest scores in Black women. In 84.8% of Black and 68.8% of White patients, the target AUC_0–12 was achieved (p = 0.027). In 31.3% of White and 9.1% of Black recipients, AUC_0–12 was <100 ng‧h/ml despite tacrolimus troughs in the target range (p = 0.027). The novel CYP3A5*3*6*7 metabolic composite was the significant covariate accounting for 15%–19% of tacrolimus variability in dose (p = 0.002); AUC_0–12 h* (p < 0.001), and Cl (p < 0.001).

Conclusions

Tacrolimus pharmacokinetics and adverse effects were different among stable kidney transplant recipient groups based upon race and sex with interpatient variability associated with the CYP3A5*3*6*7 metabolic composite. More cumulative, neurologic, and aesthetic adverse effects were noted among females. Tacrolimus regimens that consider race and sex may reduce adverse effects and enhance allograft outcomes by facilitating more patients to achieve the targeted AUC_0–12 h.

Employment status at transplant influences ethnic disparities in outcomes after deceased donor kidney transplantation

Background

African American (AA) recipients of deceased-donor (DD) kidney transplants (KT) have shorter allograft survival than recipients of other ethnic groups. Reasons for this disparity encompass complex interactions between donors and recipients characteristics.

Methods

Outcomes from 3872 AA and 19,719 European American (EA) DDs who had one kidney transplanted in an AA recipient and one in an EA recipient were analyzed. Four donor/recipient pair groups (DRP) were studied, AA/AA, AA/EA, EA/AA, and EA/EA. Survival random forests and Cox proportional hazard models were fitted to rank and evaluate modifying effects of DRP on variables associated with allograft survival. These analyses sought to identify factors contributing to the observed disparities in transplant outcomes among AA and EA DDKT recipients.

Results

Transplant era, discharge serum creatinine, delayed graft function, and DRP were among the top predictors of allograft survival and mortality among DDKT recipients. Interaction effects between DRP with the kidney donor risk index and transplant era showed significant improvement in allograft survival over time in EA recipients. However, AA recipients appeared to have similar or poorer outcomes for DDKT performed after 2010 versus before 2001; allograft survival hazard ratios (95% CI) were 1.15 (0.74, 1.76) and 1.07 (0.8, 1.45) for AA/AA and EA/AA, compared to 0.62 (0.54, 0.71) and 0.5 (0.41, 0.62) for EA/EA and AA/EA DRP, respectively. Recipient mortality improved over time among all DRP, except unemployed AA/AAs. Relative to DDKT performed pre-2001, employed AA/AAs had HR = 0.37 (0.2, 0.69) versus 0.59 (0.31, 1.11) for unemployed AA/AA after 2010.

Conclusion

Relative to DDKT performed before 2001, similar or worse overall DCAS was observed among AA/AAs, while EA/EAs experienced considerable improvement regardless of employment status, KDRI, and EPTS. AA recipients of an AA DDKT, especially if unemployed, had worse allograft survival and mortality and did not appear to benefit from advances in care over the past 20 years.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02631-4.

Discrepant subtyping of blood type A2 living kidney donors: Missed opportunities in kidney transplantation

BACKGROUND

Despite the institution of a new Kidney Allocation System in 2014, A2/A2B to B transplantation has not increased as expected. The current Organ Procurement and Transplantation Network policy requires subtyping on two separate occasions, and in the setting of discrepant results, defaulting to the A1 subtype. However, there is significant inherent variability in the serologic assays used for blood group subtyping and genotyping is rarely done.

METHODS

The National Kidney Registry, a kidney paired donation (KPD) program, performs serological typing on all A/AB donors, and in cases of non-A1/non-A1B donors, confirmatory genotyping is performed.

RESULTS

Between 2/18/2018 and 9/15/2020, 13.0% (145) of 1,111 type A donors registered with the NKR were ultimately subtyped as A2 via genotyping. Notably, 49.6% (72) of these were subtyped as A1 at their donor center, and in accordance with OPTN policy, ineligible for allocation as A2.

CONCLUSION

Inaccurate A2 subtyping represents a significant lost opportunity in transplantation, especially in KPD where A2 donors can not only facilitate living donor transplantation for O and highly sensitized candidates, but can also facilitate additional living donor transplants. This study highlights the need for improved accuracy of subtyping technique, and the need for policy changes encouraging optimal utilization of A2 donor kidneys.

A Narrative Review of Qualitative Studies Describing Access to Kidney Transplantation

BACKGROUND

This review used the Information-Motivation-Behavioral Skills (IMB) model of health behavior change to conceptualize the determinants of kidney transplant access behavior for adult patients with end-stage renal disease (ESRD).

METHODS

A narrative review of qualitative studies of patient access to kidney transplantation was undertaken. Only articles in English were accessed. The existing literature was critically analyzed using theoretical constructs of the IMB model and thematic synthesis was performed.

RESULTS

Results suggest patients having more information (greater transplant knowledge), more personal motivation (higher transplant outcomes expectations), more social motivation (more social and provider support), and more selfefficacy (confidence in navigating the transplant continuum) may be more likely to perform transplant access behaviors.

CONCLUSION

Our findings provide a framework for considering patients' levels of knowledge, motivation, and self-efficacy in future educational and behavioral interventions for ESRD patients.

Beyond Single Nucleotide Polymorphisms: CYP3A5∗3∗6∗7 Composite and ABCB1 Haplotype Associations to Tacrolimus Pharmacokinetics in Black and White Renal Transplant Recipients

Interpatient variability in tacrolimus pharmacokinetics is attributed to metabolism by cytochrome P-450 3A5 (CYP3A5) isoenzymes and membrane transport by P-glycoprotein. Interpatient pharmacokinetic variability has been associated with genotypic variants for both CYP3A5 or ABCB1. Tacrolimus pharmacokinetics was investigated in 65 stable Black and Caucasian post-renal transplant patients by assessing the effects of multiple alleles in both CYP3A5 and ABCB1. A metabolic composite based upon the CYP3A5 polymorphisms: ^∗3(rs776746), ^∗6(10264272), and ^∗7(41303343), each independently responsible for loss of protein expression was used to classify patients as extensive, intermediate and poor metabolizers. In addition, the role of ABCB1 on tacrolimus pharmacokinetics was assessed using haplotype analysis encompassing the single nucleotide polymorphisms: 1236C > T (rs1128503), 2677G > T/A(rs2032582), and 3435C > T(rs1045642). Finally, a combined analysis using both CYP3A5 and ABCB1 polymorphisms was developed to assess their inter-related influence on tacrolimus pharmacokinetics. Extensive metabolizers identified as homozygous wild type at all three CYP3A5 loci were found in 7 Blacks and required twice the tacrolimus dose (5.6 ± 1.6 mg) compared to Poor metabolizers [2.5 ± 1.1 mg (P < 0.001)]; who were primarily Whites. These extensive metabolizers had 2-fold faster clearance (P < 0.001) with 50% lower AUC^∗ (P < 0.001) than Poor metabolizers. No differences in C_{12 h} were found due to therapeutic drug monitoring. The majority of blacks (81%) were classified as either Extensive or Intermediate Metabolizers requiring higher tacrolimus doses to accommodate the more rapid clearance. Blacks who were homozygous for one or more loss of function SNPS were associated with lower tacrolimus doses and slower clearance. These values are comparable to Whites, 82% of who were in the Poor metabolic composite group. The ABCB1 haplotype analysis detected significant associations of the wildtype 1236T-2677T-3435T haplotype to tacrolimus dose (P = 0.03), CL (P = 0.023), CL/LBW (P = 0.022), and AUC^∗ (P = 0.078). Finally, analysis combining CYP3A5 and ABCB1 genotypes indicated that the presence of the ABCB1 3435 T allele significantly reduced tacrolimus clearance for all three CPY3A5 metabolic composite groups. Genotypic associations of tacrolimus pharmacokinetics can be improved by using the novel composite CYP3A5^∗3^∗4^∗5 and ABCB1 haplotypes. Consideration of multiple alleles using CYP3A5 metabolic composites and drug transporter ABCB1 haplotypes provides a more comprehensive appraisal of genetic factors contributing to interpatient variability in tacrolimus pharmacokinetics among Whites and Blacks.

The potential role of antibodies against minor blood group antigens in renal transplantation

Blood group antigens are red blood cell (RBC) surface markers comprising specific carbohydrate moieties attached to the glycolipids and glycoproteins within the membrane. In addition to the major ABO blood group antigens, at least 35 minor blood group antigens have been defined to date. These antigens have immunogenic potential and may cause a transfusion reaction. There is evidence for renal expression of antigens from the Kidd, MNS, Duffy and Lewis groups and therefore the potential for antibodies directed against these antigens to cross-react in a transplanted kidney. In individuals lacking a specific RBC antigen, antibodies may develop after de novo exposure to that antigen, in addition to the potential presence of pre-existing innate antibodies. Relatively little attention has been paid to non-ABO system antibodies, with most reports in the literature focusing on transfusion reactions rather than on any putative role in allograft rejection. Here, we review each of these antigens in the context of renal transplantation and what limited evidence there is on how such immunological risk may be assessed and managed.

Rabbit anti-thymocyte globulin (rATG) versus IL-2 receptor antagonist induction therapies in tacrolimus-based immunosuppression era: a meta-analysis

BACKGROUND

The aim of this meta-analysis is to explore the effect of IL-2RA vs rATG on the rate of acute rejection, post-transplant infections, and graft as well as patient's survival in standard- and high-risk renal transplant patients receiving tacrolimus-based maintenance immunotherapy.

METHODS

Random effects model was the method used for identifying risk difference. Confidence interval including the value 1 was used as evidence for statistically significant risk difference. Heterogeneity was assessed using Der Simonian analysis. Heterogeneity was evident at the level of P value < 0.1 RESULTS: The random effects model showed no significant differences in both acute rejection rates between IL-2RA and rATG induction therapies with relative risk of 1.24 graft survival with relative risk 0.90. Patient survival also did not demonstrate any significant difference with a relative risk of 1.19. Random effects for CMV infection showed a lesser tendency for CMV infection in IL-2RA group compared to ATG group the with a relative risk of 0.73.In subgroup analysis, the random effects model for acute rejection rates in high-risk transplants showed a higher risk of acute rejection in the IL-2RA group compared to rATG (relative risk equals 1.55) In standard-risk transplants, there were no significant differences between both groups with relative risk equals 1.02 CONCLUSIONS: This meta-analysis revealed no significant difference in patient and graft survival when using IL-2RA vs rATG with the tacrolimus-based maintenance immunosuppression era. However, subgroup analysis showed less incidence of rejection in high-risk renal transplant recipient's population using rATG compared to IL-2RA.

Socioeconomic Status and Kidney Transplant Outcomes in a Universal Healthcare System: A Population-based Cohort Study

BACKGROUND

Conflicting evidence exists regarding the relationship between socioeconomic status (SES) and outcomes after kidney transplantation.

METHODS

We conducted a population-based cohort study in a publicly funded healthcare system using linked administrative healthcare databases from Ontario, Canada to assess the relationship between SES and total graft failure (ie, return to chronic dialysis, preemptive retransplantation, or death) in individuals who received their first kidney transplant between 2004 and 2014. Secondary outcomes included death-censored graft failure, death with a functioning graft, all-cause mortality, and all-cause hospitalization (post hoc outcome).

RESULTS

Four thousand four hundred-fourteen kidney transplant recipients were included (median age, 53 years; 36.5% female), and the median (25th, 75th percentile) follow-up was 4.3 (2.1-7.1) years. In an unadjusted Cox proportional hazards model, each CAD $10000 increase in neighborhood median income was associated with an 8% decline in the rate of total graft failure (hazard ratio [HR], 0.92; 95% confidence interval [CI], 0.87-0.97). After adjusting for recipient, donor, and transplant characteristics, SES was not significantly associated with total or death-censored graft failure. However, each CAD $10000 increase in neighborhood median income remained associated with a decline in the rate of death with a functioning graft (adjusted (a)HR, 0.91; 95% CI, 0.83-0.98), all-cause mortality (aHR, 0.92; 95% CI, 0.86-0.99), and all-cause hospitalization (aHR, 0.95; 95% CI, 0.92-0.98).

CONCLUSIONS

In conclusion, in a universal healthcare system, SES may not adversely influence graft health, but SES gradients may negatively impact other kidney transplant outcomes and could be used to identify patients at increased risk of death or hospitalization.

Race and Mortality in CKD and Dialysis: Findings From the Chronic Renal Insufficiency Cohort (CRIC) Study

RATIONALE & OBJECTIVES

Few studies have investigated racial disparities in survival among dialysis patients in a manner that considers risk factors and mortality during the phase of kidney disease before maintenance dialysis. Our objective was to explore racial variations in survival among dialysis patients and relate them to racial differences in comorbid conditions and rates of death in the setting of kidney disease not yet requiring dialysis therapy.

STUDY DESIGN

Retrospective cohort study.

SETTINGS & PARTICIPANTS

3,288 black and white participants in the Chronic Renal Insufficiency Cohort (CRIC), none of whom were receiving dialysis at enrollment.

EXPOSURE

Race.

OUTCOME

Mortality.

ANALYTIC APPROACH

Cox proportional hazards regression was used to examine the association between race and mortality starting at: (1) time of dialysis initiation and (2) entry into the CRIC.

RESULTS

During 7.1 years of median follow-up, 678 CRIC participants started dialysis. Starting from the time of dialysis initiation, blacks had lower risk for death (unadjusted HR, 0.67; 95% CI, 0.51-0.87) compared with whites. Starting from baseline CRIC enrollment, the strength of the association between some risk factors and dialysis was notably stronger for whites than blacks. For example, the HR for dialysis onset in the presence (vs absence) of heart failure at CRIC enrollment was 1.30 (95% CI, 1.01-1.68) for blacks versus 2.78 (95% CI, 1.90-4.50) for whites, suggesting differential severity of these risk factors by race. When we included deaths occurring both before and after dialysis, risk for death was higher among blacks (vs whites) starting from CRIC enrollment (HR, 1.41; 95% CI, 1.22-1.64), but this finding was attenuated in adjusted models (HR, 1.08; 95% CI, 0.91-1.28).

LIMITATIONS

Residual confounding.

CONCLUSIONS

The apparent survival advantage among blacks over whites treated with dialysis may be attributed to selected transition of a subset of whites with more severe comorbid conditions onto dialysis.

Surgeon crossover between pediatric and adult centers is associated with decreased rate of loss to follow-up among adolescent renal transplantation recipients

The risk of adverse outcomes for pediatric renal transplant patients is highest during the transition from pediatric to adult care. While there have been many studies focus on graft failure and death, loss to follow-up likely plays a large role in patient outcomes. We hypothesize patients are lost to follow-up during this transition period and that patients transplanted at pediatric centers with a closely affiliated adult center (AFFs) are less likely to suffer from fragmentation of care and become lost to follow-up. AFFs were defined as those pediatric centers whose transplant surgeons were also on staff at an adult center and were identified using center websites. We included patients undergoing renal transplantation at <=18 years of age and had data for the entire transition period on the Scientific Registry of Transplant Recipients (n = 6,762, 92.3% in 95 AFFs). 32% of patients were lost to follow-up. On regression, patients transplanted at AFF were 33% less likely to be lost to follow-up compared with those from non-AFF (OR 0.67 CI 0.54-0.82, P < 0.01). The proportion of patients lost to follow-up during the transition period is remarkably high, but lower among recipients transplanted at AFFs. Poor follow-up may be mitigated by improving integration of care.

Predicting Physician Assistant Program Matriculation Among Diverse Applicants: The Influences of Underrepresented Minority Status, Age, and Gender

PURPOSE

Health professions schools can foster a diverse medical workforce by ensuring equal educational access for students of varied backgrounds. This study examined how physician assistant (PA) applicants' demographic characteristics and prior academic history affected likelihood of PA program matriculation.

METHOD

The authors used national application data from the 2015-2016 PA application cycle to investigate associations between applicants' underrepresented minority (URM) status, age, and gender, and likelihood of matriculating into a PA program. Effects were examined alone and after adjusting for other demographics and potential confounders (number of applications submitted, patient care hours, academic achievement). The authors tested whether odds of matriculation differed among demographic subgroups with and without current Graduate Record Examinations (GRE) scores.

RESULTS

In univariate models, likelihood of matriculation was lower among URM, older, and male applicants. In fully adjusted models, the URM effect became nonsignificant and the gender effect reversed, while older applicants remained less likely to matriculate. URM and age, but not gender, effects differed by GRE status; only URMs and older applicants without current GRE scores were less likely to matriculate than non-URMs and younger applicants.

CONCLUSIONS

Findings that URMs, older individuals, and men had lower matriculation odds changed when controlling for academic achievement and GRE status, indicating the importance of these components in the admissions process. URM and age findings were contingent on GRE status such that odds of matriculation decreased among URM and older applicants without GRE scores, suggesting that standardized test requirements may be a barrier to PA workforce diversity.

Impact of Rural Residence on Kidney Transplant Rates Among Waitlisted Candidates in the VA Transplant Programs

BACKGROUND

Although proportionally more veterans live in rural areas compared to nonveterans, the impact of rurality status on kidney transplantation (KTP) access among veterans is unknown. Our objective was to study KTP rates among veterans listed for KTP and to compare the impact of rurality status on KTP rates among veterans and nonveterans.

METHODS

Retrospective cohort study of adult patients waitlisted per the United Network for Organ Sharing from January 2000 to December 2014. Patient characteristics were compared using Chi-square or t tests, as appropriate, by veteran status and patient rurality. Multivariable competing-risks Cox regression was performed.

RESULTS

The study sample included 3281 veterans receiving care in Veteran Health Administration transplant programs and 445 177 nonveterans. Veterans, compared to nonveterans, were older (57 versus 50 y; P < 0.001), more likely to be male (96% versus 60%; P < 0.001) or diabetic at waitlisting (51% versus 41%; P < 0.001), and less likely be an urban resident (79% versus 84%; P < 0.001). Among veterans, dialysis duration prior to registration was longer among urban compared to all other rurality types (810 ± 22.1 d versus 632 to 702 ± 41.6 to 77.6 d; P = 0.02). In multivariate competing risks models, there was no evidence that the hazard of transplant among veterans differs by residential rurality.

CONCLUSIONS

Among waitlisted veterans served by Veteran Health Administration transplant programs, residential rurality status does not portend longer waiting time for KTP.

Enabling Conversations: African American Patients' Changing Perceptions of Kidney Transplantation

BACKGROUND

Racial disparities in access to kidney transplantation (KTX) among African Americans (AAs) have been attributed in part to insufficient patient education. Interventions are needed to provide AAs with culturally sensitive, understandable information that increases their capacity to pursue KTX. Research about the factors that activated patients to pursue KTX is necessary to inform such interventions; however, few studies have yielded this type of information.

METHODS

We conducted focus groups and one-on-one interviews with 26 AA referred, listed, or transplanted patients and 3 nephrologists to explore decisional factors that foster pursuit of KTX. Interviews were recorded and transcribed, and qualitative analytic methods to identify themes and subthemes were applied in an effort to inform message content for a future educational video intervention.

RESULTS

Three themes emerged from thematic content analysis: (1) healthcare provider communication, (2) exposure to peer transplant success, and (3) family encouragement. Enabling provider communication techniques include repetition about the KTX option, optimistic messaging about KTX access, and comforting conversations about the KTX process.

CONCLUSION

We identified information based on patient views and experiences to help inspire and develop animated videos designed to activate patients towards KTX. Interventions are needed that address informational gaps and focus on emotion to improve patients' experiences and ability to understand transplant opportunities.

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.

Impact of the new kidney allocation system A2/A2B → B policy on access to transplantation among minority candidates

Blood group B candidates, many of whom represent ethnic minorities, have historically had diminished access to deceased donor kidney transplantation (DDKT). The new national kidney allocation system (KAS) preferentially allocates blood group A2/A2B deceased donor kidneys to B recipients to address this ethnic and blood group disparity. No study has yet examined the impact of KAS on A2 incompatible (A2i) DDKT for blood group B recipients overall or among minorities. A case-control study of adult blood group B DDKT recipients from 2013 to 2017 was performed, as reported to the Scientific Registry of Transplant Recipients. Cases were defined as recipients of A2/A2B kidneys, whereas controls were all remaining recipients of non-A2/A2B kidneys. A2i DDKT trends were compared from the pre-KAS (1/1/2013-12/3/2014) to the post-KAS period (12/4/2014-2/28/2017) using multivariable logistic regression. Post-KAS, there was a 4.9-fold increase in the likelihood of A2i DDKT, compared to the pre-KAS period (odds ratio [OR] 4.92, 95% confidence interval [CI] 3.67-6.60). However, compared to whites, there was no difference in the likelihood of A2i DDKT among minorities post-KAS. Although KAS resulted in increasing A2/A2B→B DDKT, the likelihood of A2i DDKT among minorities, relative to whites, was not improved. Further discussion regarding A2/A2B→B policy revisions aiming to improve DDKT access for minorities is warranted.

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.

Mycophenolic Acid and Its Metabolites in Kidney Transplant Recipients: A Semimechanistic Enterohepatic Circulation Model to Improve Estimating Exposure

Mycophenolic acid (MPA) is an approved immunosuppressive agent widely prescribed to prevent rejection after kidney transplantation. Wide between-subject variability (BSV) in MPA exposure exists which in part may be due to variability in enterohepatic recirculation (EHC). Several modeling strategies were developed to evaluate EHC as part of MPA pharmacokinetics, however mechanistic representation of EHC is limited. These models have not provided a satisfactory representation of the physiology of EHC in their modeling assumptions. The aim of this study was i) to develop an integrated model of MPA (total and unbound) and its metabolites (MPAG and acyl-MPAG) in kidney recipients, where this model provides a more physiological representation of EHC process, and ii) to evaluate the effect of donor and recipient clinical covariates and genotypes on MPA disposition. A five-compartment model with first-order input into an unbound MPA compartment connected to the MPAG, acyl-MPAG, and gallbladder compartment best fit the data. To represent the EHC process, the model was built based on the physiological concepts related to the hepatobiliary system and the gallbladder filling and emptying processes. The effect of cyclosporine versus tacrolimus on clearance of unbound MPA was included in the base model. Covariate analysis showed creatinine clearance to be significant on oral clearance of unbound MPA. The hepatic nuclear factor 1 alpha (HNF1A) genetic single nucleotide polymorphism (SNP) (rs2393791) in the recipient significantly affected the fraction of enterohepatically-circulated drug. Oral clearance of MPAG was affected by recipient IMPDH1 SNP (rs2288553), diabetes at the time of transplant, and donor sex.

Impact of CYP3A5 genomic variances on clinical outcomes among African American kidney transplant recipients

Little is known about the impact of CYP3A5 polymorphisms on transplantation outcomes among African American (AA) kidney transplant recipients (KTRs). To assess this issue, clinical outcomes were compared between AA CYP3A5*1 expressers and nonexpressers. This retrospective cohort study analyzed AA KTRs. Biopsy-proven acute rejection (BPAR), delayed graft function (DGF), glomerular filtration rate (GFR), infections, and tacrolimus dosing requirements were examined in 106 immunologically high-risk AA kidney transplant patients over a 2-year follow-up period. In CYP3A5*1 expressers compared to nonexpressers, the incidence of BPAR was significantly higher in the first 6 months (13% vs 0%; P = .016) compared to 24 months (13% vs 7%; P = .521). Tacrolimus total daily dose at first therapeutic level was significantly higher in CYP3A5*1 expressers (12 mg/day) compared to nonexpressers (8 mg/day; P < .001). Compared to CYP3A5*1 nonexpressers, DGF incidence was significantly higher among CYP3A5*1 expressers (27.6% vs 6.7%; P = .006). By contrast, median GFR was significantly higher in CYP3A5*1 expressers compared to nonexpressers (54.5 mL/min vs 50.0 mL/min; P = .003) at 24 months. The findings from this retrospective study suggest that AAs with CYP3A5*1 expression require 50% more tacrolimus and have an increased incidence of DGF and acute rejection.

Alemtuzumab Induction Is Associated With an Equalization of Outcomes Between White and African American Kidney Transplant Recipients

OBJECTIVES

Our aim was to assess outcomes in White and African American kidney transplant recipients after induction with alemtuzumab.

MATERIALS AND METHODS

We performed a retrospective study of 464 patients who received deceased-donor kidney transplants and were induced with alem-tuzumab between March 2006 and May 2015. We evaluated ethnic influences on patient and graft survival, delayed graft function, allograft failure, and rejection.

RESULTS

There were 337 White (67.3%) and 127 African American (25.3%) patients. We observed no significant differences in 1-, 3-, 5-, and 7- year death-censored graft survival. We also observed no significant differences in 1-, 3-, and 5-year patient survival rates. Having African American ethnicity was not a significant predictor of rejection, graft survival, or patient survival.

CONCLUSIONS

Our results indicate that recipient ethnicity is not a predictor of rejection, graft survival, or patient survival. White and African American kidney transplant recipients induced with alemtuzumab experienced an equalization of outcomes.

Outcomes of Deceased Donor Kidney Offers to Patients at the Top of the Waiting List

BACKGROUND AND OBJECTIVES

Transplant centers may accept or refuse deceased-donor kidneys that are offered to their patients at the top of the waiting list. We sought to determine the outcomes of deceased-donor kidney offers and their association with characteristics of waitlisted patients and organ donors.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We examined all 7 million deceased-donor adult kidney offers in the United States from 2007 to 2012 that led to eventual transplantation. Data were obtained from the national organ allocation system through the United Network of Organ Sharing. The study cohort consisted of 178,625 patients waitlisted for a deceased-donor kidney transplant and 31,230 deceased donors. We evaluated offers made to waitlisted patients and their outcomes (transplantation or specific reason for refusal).

RESULTS

Deceased-donor kidneys were offered a median of seven times before being accepted for transplantation. The most common reasons for refusal of an offer were donor-related factors, e.g., age or organ quality (3.2 million offers, 45.0%), and transplant center bypass, e.g., minimal acceptance criteria not met (3.2 million offers, 44.0%). After adjustment for characteristics of waitlisted patients, organ donors, and transplant centers, male (odds ratio [OR], 0.93; 95% confidence interval [95% CI], 0.91 to 0.95) and Hispanic (OR, 0.96; 95% CI, 0.93 to 0.99) waitlisted patients were less likely to have an offer accepted than female and white patients, respectively. The likelihood of offer acceptance varied greatly across transplant centers (interquartile ratio, 2.28).

CONCLUSIONS

Transplant centers frequently refuse deceased-donor kidneys. Such refusals differ by patient and donor characteristics, may contribute to disparities in access to transplantation, and vary greatly across transplant centers.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2017_07_27_Huml.mp3.

Effect of Replacing Race With Apolipoprotein L1 Genotype in Calculation of Kidney Donor Risk Index

Renal allografts from deceased African American donors with two apolipoprotein L1 gene (APOL1) renal-risk variants fail sooner than kidneys from donors with fewer variants. The Kidney Donor Risk Index (KDRI) was developed to evaluate organ offers by predicting allograft longevity and includes African American race as a risk factor. Substituting APOL1 genotype for race may refine the KDRI. For 622 deceased African American kidney donors, we applied a 10-fold cross-validation approach to estimate contribution of APOL1 variants to a revised KDRI. Cross-validation was repeated 10 000 times to generate distribution of effect size associated with APOL1 genotype. Average effect size was used to derive the revised KDRI weighting. Mean current-KDRI score for all donors was 1.4930 versus mean revised-KDRI score 1.2518 for 529 donors with no or one variant and 1.8527 for 93 donors with two variants. Original and revised KDRIs had comparable survival prediction errors after transplantation, but the spread in Kidney Donor Profile Index based on presence or absence of two APOL1 variants was 37 percentage points. Replacing donor race with APOL1 genotype in KDRI better defines risk associated with kidneys transplanted from deceased African American donors, substantially improves KDRI score for 85-90% of kidneys offered, and enhances the link between donor quality and recipient need.

Overall Graft Loss Versus Death-Censored Graft Loss: Unmasking the Magnitude of Racial Disparities in Outcomes Among US Kidney Transplant Recipients

BACKGROUND

Black kidney transplant recipients experience disproportionately high rates of graft loss. This disparity has persisted for 40 years, and improvements may be impeded based on the current public reporting of overall graft loss by US regulatory organizations for transplantation.

METHODS

Longitudinal cohort study of kidney transplant recipients using a data set created by linking Veterans Affairs and US Renal Data System information, including 4918 veterans transplanted between January 2001 and December 2007, with follow-up through December 2010. Multivariable analysis was conducted using 2-stage joint modeling of random and fixed effects of longitudinal data (linear mixed model) with time to event outcomes (Cox regression).

RESULTS

Three thousand three hundred six non-Hispanic whites (67%) were compared with 1612 non-Hispanic black (33%) recipients with 6.0 ± 2.2 years of follow-up. In the unadjusted analysis, black recipients were significantly more likely to have overall graft loss (hazard ratio [HR], 1.19; 95% confidence interval [95% CI], 1.07-1.33), death-censored graft loss (HR, 1.67; 95% CI, 1.45-1.92), and lower mortality (HR, 0.83; 95% CI, 0.72-0.96). In fully adjusted models, only death-censored graft loss remained significant (HR, 1.38; 95% CI, 1.12-1.71; overall graft loss [HR, 1.08; 95% CI, 0.91-1.28]; mortality [HR, 0.84; 95% CI, 0.67-1.06]). A composite definition of graft loss reduced the magnitude of disparities in blacks by 22%.

CONCLUSIONS

Non-Hispanic black kidney transplant recipients experience a substantial disparity in graft loss, but not mortality. This study of US data provides evidence to suggest that researchers should focus on using death-censored graft loss as the primary outcome of interest to facilitate a better understanding of racial disparities in kidney transplantation.

Access to Kidney Transplantation among HIV-Infected Waitlist Candidates

BACKGROUND AND OBJECTIVES

Kidney transplantation among HIV-infected patients with ESRD confers a significant survival benefit over remaining on dialysis. Given the high mortality burden associated with dialysis, understanding access to kidney transplantation after waitlisting among HIV+ candidates is warranted.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from the Scientific Registry of Transplant Recipients were linked to Intercontinental Marketing Statistics pharmacy fills (January 1, 2001 to October 1, 2012) so that we could identify and study 1636 HIV+ (defined as having filled one or more antiretroviral medications unique to HIV treatment) and 72,297 HIV- kidney transplantation candidates.

RESULTS

HIV+ waiting list candidates were more often young (<50 years old: 62.7% versus 37.6%; P<0.001), were more often men (75.2% versus 59.3%; P<0.001), were more often black (73.6% versus 27.9%; P<0.001), had longer time on dialysis (years: 2.5 versus 0.8; P<0.001), were more often coinfected with hepatitis C virus (9.0% versus 3.9%; P<0.001), and were less likely to remain active on the waiting list (37.7% versus 49.4%; P<0.001). Waitlist mortality among HIV+ candidates was similar compared with HIV- candidates (adjusted hazard ratio, 1.03; 95% confidence interval, 0.89 to 1.20; P=0.67). In contrast, likelihood of living donor kidney transplantation was 47% lower (adjusted hazard ratio, 0.53; 95% confidence interval, 0.44 to 0.64; P<0.001), and there was a trend toward lower likelihood of deceased donor kidney transplantation (adjusted hazard ratio, 0.87; 95% confidence interval, 0.74 to 1.01; P=0.07) compared with in HIV- candidates.

CONCLUSIONS

Our findings highlight the need for additional study to better understand disparities in access to kidney transplantation, particularly living donor kidney transplantation, among HIV+ kidney waitlist candidates.

Mortality after Renal Allograft Failure and Return to Dialysis

INTRODUCTION

The outcomes of patients who fail their kidney transplant and return to dialysis (RTD) has not been investigated in a nationally representative sample. We hypothesized that variations in management of transplant chronic kidney disease stage 5 leading to kidney allograft failure (KAF) and RTD, such as access, nutrition, timing of dialysis, and anemia management predict long-term survival.

METHODS

We used an incident cohort of patients from the United States Renal Data System who initiated hemodialysis between January 1, 2003 and December 31, 2008, after KAF. We used Cox regression analysis for statistical associations, with mortality as the primary outcome.

RESULTS

We identified 5,077 RTD patients and followed them for a mean of 30.9 ± 22.6 months. Adjusting for all possible confounders at the time of RTD, the adjusted hazards ratio (AHR) for death was increased with lack of arteriovenous fistula at initiation of dialysis (AHR 1.22, 95% CI 1.02-1.46, p = 0.03), albumin <3.5 g/dL (AHR 1.33, 95% CI 1.18-1.49, p = 0.0001), and being underweight (AHR 1.30, 95% CI 1.07-1.58, p = 0.006). Hemoglobin <10 g/dL (AHR 0.96, 95% CI 0.86-1.06, p = 0.46), type of insurance, and zip code-based median household income were not associated with higher mortality. Glomerular filtration rate <10 mL/min/1.73 m2 at time of dialysis initiation (AHR 0.83, 95% CI 0.75-0.93, p = 0.001) was associated with reduction in mortality.

CONCLUSIONS

Excess mortality risk observed in patients starting dialysis after KAF is multifactorial, including nutritional issues and vascular access. Adequate preparation of patients with failing kidney transplants prior to resuming dialysis may improve outcomes.

Outcome disparities between African Americans and Caucasians in contemporary kidney transplant recipients

BACKGROUND

Racial disparities in African-American (AA) kidney transplant have persisted for nearly 40 years, with limited data available on the scope of this issue in the contemporary era of transplantation.

METHODS

Descriptive retrospective cohort study of US registry data including adult solitary kidney transplants between Jan 1, 2005 to Dec 31, 2009.

RESULTS

60,695 recipients were included; 41,426 Caucasians (68%) and 19,269 AAs (32%). At baseline, AAs were younger, had lower college graduation rates, were more likely to be receiving public health insurance and have diabetes. At one-year post-transplant, AAs had 62% higher risk of graft loss (RR 1.62, 95% CI 1.50-1.75) which increased to 93% at five years (RR 1.93, 95% CI 1.85-2.01). Adjusted risk of graft loss, accounting for baseline characteristics, was 60% higher in AAs (HR 1.61 [1.52-1.69]). AAs had significantly higher risk of acute rejection and delayed graft function.

CONCLUSION

AAs continue to experience disproportionately high rates of graft loss within the contemporary era of transplant, which are related to a convergence of an array of socioeconomic and biologic risk factors.

Profiling risk for acute rejection in kidney transplantation: recipient age is a robust risk factor

Careful management of immunosuppression is paramount to prevent acute rejection in kidney transplantation. We studied a cohort of 139,875 kidney transplant recipients from the Organ Procurement and Transplantation Network (OPTN) database between 2002 and 2013. We confirmed the analysis with a cohort of 35,277 who received thymoglobulin induction with tacrolimus maintenance, and a third cohort of 12,161 recipients who received basiliximab induction with tacrolimus maintenance. We performed multivariate logistic regression analyses on data from all three cohorts and identified independent risk factors for treated acute rejection at 1 year. Recipient age was a robust risk factor for rejection in all three cohorts in a dose response pattern. Young age (18-25 years) was among the strongest risk factors for rejection in all three cohorts; thymoglobulin cohort: OR 1.87 (1.59-2.19); basiliximab cohort: OR 2.41 (1.89-3.05); and inclusive cohort: OR 1.97 (1.83-2.12). The opposite was true for old age (65-69 years); thymoglobulin cohort: OR 0.69 (0.59-0.81); basiliximab cohort: OR 0.77 (0.62-0.96); and inclusive cohort: OR 0.75 (0.70-0.80). This study is unique because it is the largest and most comprehensive multivariate analysis that demonstrates recipient age is a robust risk factor for acute rejection in an inverse dose response pattern.

Disparate rates of acute rejection and donor-specific antibodies among high-immunologic risk renal transplant subgroups receiving antithymocyte globulin induction

Lymphocyte-depleting induction lowers acute rejection (AR) rates among high-immunologic risk (HIR) renal transplant recipients, including African Americans (AAs), retransplants, and the sensitized. It is unclear whether different HIR subgroups experience similarly low rates of AR. We aimed to describe the incidence of AR and de novo donor-specific antibody (dnDSA) among HIR recipients categorized by age, race, or donor type. All received antithymocyte globulin (ATG) induction and triple maintenance immunosuppression. A total of 464 HIR recipients from 2007 to 2014 were reviewed. AR and dnDSA rates at 1 year for the entire population were 14% and 27%, respectively. AR ranged from 6.7% among living donor (LD) recipients to 30% in younger AA deceased donor (DD) recipients. De novo donor-specific antibody at 1 year ranged from 7% in older non-AA LD recipients to 32% in AAs. AA race remained as an independent risk factor for AR among DD recipients and for dnDSA among all HIR recipients. Development of both AR and dnDSA within the first year was associated with a 54% graft survival at 5 years and was an independent risk factor for graft loss. Despite utilization of recommended immunosuppression for HIR recipients, substantial disparities exist among subgroups, warranting further consideration of individualized immunosuppression in certain HIR subgroups.

Culturally Responsive Interventions to Enhance Immunosuppressive Medication Adherence in Older African American Kidney Transplant Recipients

Context

Immunosuppressive medication nonadherence is variable among older kidney transplant recipients and is a problem in African American recipients despite the severe consequences of this behavior. Many factors place older African American recipients at risk for medication nonadherence.

Objective

To provide an overview of interventions to enhance immunosuppressive medication adherence in older African American kidney transplant recipients using a culturally responsive model. Culturally sensitive, innovative, and transformation interventions are discussed. Situations when each intervention would be most and least appropriate are described.

Conclusion

Moving culturally appropriate interventions forward into practice and testing their effectiveness in improving adherence outcomes in vulnerable, older African American kidney transplant recipients is a worthy practice and research goal for transplant nursing.

A randomized, prospective comparison of transition to sirolimus-based CNI-minimization or withdrawal in African American kidney transplant recipients

BACKGROUND

There is a lack of conclusive evidence to suggest if calcineurin inhibitor (CNI) withdrawal or minimization with sirolimus is the best strategy for African Americans.

METHODS

This was a randomized, prospective, open-label, pilot study comparing the two mammalian target of rapamycin (mTOR) transition strategies in adult African Americans between six and 24 wk post-transplant. The primary outcome was a comparison of the eGFR at one yr after conversion.

RESULTS

Forty patients were randomized and analyzed in an intent-to-treat fashion. Median day of transition was day 96 (withdrawal) and 68 (minimization). Patients in the CNI-withdrawal group (n = 23) had significantly higher eGFR at one yr compared to the CNI-minimization group (n = 17, 73 vs. 56 mL/min, p = 0.03), as well as a significantly larger increase in eGFR from baseline (12 vs. 5 mL/min, p = 0.03). There were no differences in infections, acute rejection, death, or graft loss. Both regimens were constrained by disproportionately high discontinuation rates despite modest toxicity profiles.

CONCLUSION

In spite of considerable withdrawal rate across both study arms, African American kidney transplant recipients who underwent early transition to a sirolimus-based CNI-withdrawal regimen had significantly better graft function at one yr compared to those transitioned to a sirolimus-based CNI-minimization regimen. Clinicaltrials.gov identifier: NCT01005706.

Kidney transplantation in the Hispanic population

Hispanic race and low socioeconomic status are established predictors of disparity in access to kidney transplantation. This single-center retrospective review was undertaken to determine whether Hispanic race predicted kidney transplant outcomes. A total of 720 patients underwent kidney transplantation from January 1, 2004 to December 31, 2013, including 398 Hispanic patients and 322 non-Hispanic patients. Hispanic patients were significantly younger (p < 0.0001), on hemodialysis for longer (p = 0.0018), had a greater percentage with public insurance (p < 0.0001), more commonly had diabetes as the cause of end-stage renal disease (p = 0.0167), and had a lower percentage of living donors (p = 0.0013) compared to non-Hispanic patients. There was no difference in one-, five-, and 10-yr graft (97%, 81%, and 61% vs. 95%, 76%, and 42% p = 0.18) or patient survival (98%, 90%, and 84% vs. 97%, 87%, and 69% p = 0.11) between the Hispanic and non-Hispanic recipients. Multivariate analysis identified increased recipient age and kidney donor profile index to be predictive of lower graft survival and increasing recipient age to be predictive of lower patient survival. In the largest single-center study on kidney transplantation outcomes in Hispanic patients, there is no difference in graft and recipient survival between Hispanic and non-Hispanic kidney transplant patients, and in multivariate analysis, Hispanic race is not a risk factor for graft or patient survival.