Similar outcomes among black and white renal allograft recipients

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.

Racialized and Immigrant Status and the Pursuit of Living Donor Kidney Transplant - a Canadian Cohort Study

Introduction

Both immigrant and racialized status may be associated with the pursuit of living donor kidney transplant (LDKT).

Methods

This study was a secondary analysis of a convenience cross-sectional sample of patients with kidney failure in Toronto, obtained from our "Comprehensive Psychosocial Research Data System" research database. The exposures included racialized, immigrant, and combined immigrant and racialized status (White nonimmigrant, racialized nonimmigrant, White immigrant and racialized immigrant). Outcomes include the following: (i) having spoken about LDKT with others, (ii) having a potential living donor (LD) identified, (iii) having allowed others to share the need for LDKT, (iv) having directly asked a potential donor to be tested, and (v) accept a hypothetical LDKT offer. We assessed the association between exposure and outcomes using univariable, and multivariable binary or multinominal logistic regression (reference: White or White nonimmigrant participants).

Results

Of the 498 participants, 281 (56%) were immigrants; 142 (28%) were African, Caribbean, and Black (ACB); 123 (25%) were Asian; and 233 (47%) were White. Compared to White nonimmigrants, racialized immigrants (relative risk ratio [RRR]: 2.98; 95% confidence interval [CI]: 1.76-5.03) and racialized nonimmigrants (RRR: 2.84; 95% CI: 1.22-6.65) were more likely not to have spoken about LDKT with others (vs. having spoken or planning to do so). Both racialized immigrant (odds ratio [OR]: 4.07; 95% CI: 2.50-6.34), racialized nonimmigrants (OR: 2.68; 95% CI: 1.31-5.51) and White immigrants (OR: 2.68; 95% CI: 1.43-5.05) were more likely not to have a potential LD identified.

Conclusion

Both racialized and immigrant status are associated with less readiness to pursue LDKT. Supporting patients to communicate their need for LDKT may improve equitable access to LDKT.

Exploring barriers to living donor kidney transplant for African, Caribbean and Black communities in the Greater Toronto Area, Ontario: a qualitative study protocol

INTRODUCTION

Living donor (LD) kidney transplant (KT) is the best treatment option for many patients with kidney failure as it improves quality of life and survival compared with dialysis and deceased donor KT. Unfortunately, LDKT is underused, especially among groups marginalised by race and ethnicity. African, Caribbean and Black (ACB) patients are 60%-70% less likely to receive LDKT in Canada compared with white patients. Research from the USA and the UK suggests that mistrust, cultural and generational norms, access, and affordability may contribute to inequities. To date, no Canadian studies have explored the beliefs and behaviours related to LDKT in ACB communities. Research approaches that use a critical, community-based approach can help illuminate broader structural factors that may shape individual beliefs and behaviours. In this qualitative study, we will investigate barriers to accessing LDKT in ACB communities in the Greater Toronto Area, to enhance our understanding of the perspectives and experiences of ACB community members, both with and without lived experience of chronic kidney disease (CKD).

METHODS AND ANALYSIS

Hospital-based and community-based recruitment strategies will be used to recruit participants for focus groups and individual interviews. Participants will include self-identified ACB individuals with and without experiences of CKD and nephrology professionals. Collaboration with ACB community partners will facilitate a community-based research approach. Data will be analysed using reflexive thematic analysis and critical race theory. Findings will be revised based on feedback from ACB community partners.

ETHICS AND DISSEMINATION

This study has been approved by the University Health Network Research Ethics Board UHN REB file #15-9775. Study findings will contribute to the codevelopment of culturally safe and responsive educational materials to raise awareness about CKD and its treatments and to improve equitable access to high-quality kidney care, including LDKT, for ACB patients.

Donor characteristics and their impact on kidney transplantation outcomes: Results from two nationwide instrumental variable analyses based on outcomes of donor kidney pairs accepted for transplantation

BACKGROUND

Donor-characteristics and donor characteristics-based decision algorithms are being progressively used in the decision process whether or not to accept an available donor kidney graft for transplantation. While this may improve outcomes, the performance characteristics of the algorithms remains moderate. To estimate the impact of donor factors of grafts accepted for transplantation on transplant outcomes, and to test whether implementation of donor-characteristics-based algorithms in clinical decision-making is justified, we applied an instrumental variable analysis to outcomes for kidney donor pairs transplanted in different individuals.

METHODS

This analysis used (dis)congruent outcomes of kidney donor pairs as an instrument and was based on national transplantation registry data for all donor kidney pairs transplanted in separate individuals in the Netherlands (1990-2018, 2,845 donor pairs), and the United Kingdom (UK, 2000-2018, 11,450 pairs). Incident early graft loss (EGL) was used as the primary discriminatory factor. It was reasoned that a scenario with a dominant impact of donor variables on transplantation outcomes would result in high concordance of EGL in both recipients, whilst dominance of asymmetrical outcomes could indicate a more complex scenario, involving an interaction of donor, procedural and recipient factors.

FINDINGS

Incidences of congruent EGL (Netherlands: 1·2%, UK: 0·7%) were slightly lower than the arithmetical (stochastic) incidences, suggesting that once a graft has been accepted for transplantation, donor factors minimally contribute to incident EGL. A long-term impact of donor factors was explored by comparing outcomes for functional grafts from donor pairs with asymmetrical vs. symmetrical outcomes. Recipient survival was similar for both groups, but a slightly compromised graft survival was observed for grafts with asymmetrical outcomes in the UK cohort: (10-years Hazard Ratio for graft loss: 1·18 [1·03-1·35] p<0·018); and 5 years eGFR (48·6 [48·3-49·0] vs. 46·0 [44·5-47·6] ml/min in the symmetrical outcome group, p<0·001).

INTERPRETATION

Our results suggest that donor factors for kidney grafts deemed acceptable for transplantation impact minimally on transplantation outcomes. A strong reliance on donor factors and/or donor-characteristics-based decision algorithms could result in unjustified rejection of grafts. Future efforts to optimize transplant outcomes should focus on a better understanding of the recipient factors underlying transplant outcomes.

FUNDING

None.

Use and Outcomes of Induction Therapy in Well-Matched Kidney Transplant Recipients

BACKGROUND AND OBJECTIVES

The optimal induction treatment in low-immune risk kidney transplant recipients is uncertain. We therefore investigated the use and outcomes of induction immunosuppression in a low-risk cohort of patients who were well matched with their donor at HLA-A, -B, -DR, -DQB1 on the basis of serologic typing.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Our study was an observational study of first adult kidney-only transplant recipients in the United States recorded by the Organ Procurement and Transplant Network.

RESULTS

Among 2976 recipients, 57% were treated with T cell-depleting antibodies, 28% were treated with an IL-2 receptor antagonist, and 15% were treated without induction. There was no difference in allograft survival, death-censored graft survival, or death with function between patients treated with an IL-2 receptor antagonist and no induction therapy. In multivariable models, patients treated with T cell-depleting therapy had a similar risk of graft loss from any cause, including death (hazard ratio, 1.19; 95% confidence interval, 0.98 to 1.45), compared with patients treated with an IL-2 receptor antagonist or no induction. The findings were consistent in subgroup analyses of Black recipients, patients grouped by calculated panel reactive antibody, and donor source. The incidence of acute rejection at 1 year was low (≤5%) and did not vary between treatment groups.

CONCLUSIONS

Use of induction therapy with T cell-depleting therapy or IL-2 receptor antagonists in first kidney transplant recipients who are well matched with their donor at the HLA-A, -B, -DR, -DQB1 gene loci is not associated with improved post-transplant outcomes.

Significance of Ethnic Factors in Immunosuppressive Therapy Management After Organ Transplantation

Clinical outcomes after organ transplantation have greatly improved in the past 2 decades with the discovery and development of immunosuppressive drugs such as calcineurin inhibitors, antiproliferative agents, and mammalian target of rapamycin inhibitors. However, individualized dosage regimens have not yet been fully established for these drugs except for therapeutic drug monitoring-based dosage modification because of extensive interindividual variations in immunosuppressive drug pharmacokinetics. The variations in immunosuppressive drug pharmacokinetics are attributed to interindividual variations in the functional activity of cytochrome P450 enzymes, UDP-glucuronosyltransferases, and ATP-binding cassette subfamily B member 1 (known as P-glycoprotein or multidrug resistance 1) in the liver and small intestine. Some genetic variations have been found to be involved to at least some degree in pharmacokinetic variations in post-transplant immunosuppressive therapy. It is well known that the frequencies and effect size of minor alleles vary greatly between different races. Thus, ethnic considerations might provide useful information for optimizing individualized immunosuppressive therapy after organ transplantation. Here, we review ethnic factors affecting the pharmacokinetics of immunosuppressive drugs requiring therapeutic drug monitoring, including tacrolimus, cyclosporine, mycophenolate mofetil, sirolimus, and everolimus.

Barriers to Accessing Kidney Transplantation Among Populations Marginalized by Race and Ethnicity in Canada: A Scoping Review Part 2-East Asian, South Asian, and African, Caribbean, and Black Canadians

BACKGROUND

Kidney transplantation (KT), a treatment option for end-stage kidney disease (ESKD), is associated with longer survival and improved quality of life compared with dialysis. Inequities in access to KT, and specifically, living donor kidney transplantation (LDKT), have been documented in Canada, along various demographic dimensions. In this article, we review existing evidence about inequitable access to KT and LDKT for patients from communities marginalized by race and ethnicity in Canada.

OBJECTIVE

To characterize the currently published data on rates of KT and LDKT among East Asian, South Asian, and African, Caribbean, and Black (ACB) Canadian communities and to answer the research question, "what factors may influence inequitable access to KT among East Asian, South Asian, and ACB Canadian communities?."

ELIGIBILITY CRITERIA

Databases and gray literature were searched in June and November 2020 for full-text original research articles or gray literature resources addressing KT access or barriers in East Asian, South Asian, and ACB Canadian communities. A total of 25 articles were analyzed thematically.

SOURCES OF EVIDENCE

Gray literature and CINAHL, OVID Medline, OVID Embase, and Cochrane databases.

CHARTING METHODS

Literature characteristics were recorded and findings which described rates of and factors that influence access to KT were summarized in a narrative account. Key themes were subsequently identified and synthesized thematically in the review.

RESULTS

East Asian, South Asian, and ACB communities in Canada face barriers in accessing culturally appropriate medical knowledge and care and experience inequitable access to KT. Potential barriers include gaps in knowledge about ESKD and KT, religious and spiritual concerns, stigma of ESKD and KT, health beliefs, social determinants of health, and experiences of systemic racism in health care.

LIMITATIONS

This review included literature that used various methodologies and did not assess study quality. Data on ethnicity and race were not reported or defined in a standardized manner. The communities examined in this review are not homogeneous and views on organ donation and KT vary by individual.

CONCLUSIONS

Our review has identified potential barriers for communities marginalized by race and ethnicity in accessing KT and LDKT. Further research is urgently needed to better understand the barriers and support needs of these communities, and to develop strategies to improve equitable access to LDKT for the growingly diverse population in Canada.

Racial disparities in COVID-19 hospitalizations do not lead to disparities in outcomes

OBJECTIVES

The objective of the study is the identification of racial differences in characteristics and comorbidities in patients hospitalized for COVID-19 and the impact on outcomes.

STUDY DESIGN

The study design is a retrospective observational study.

METHODS

Data for all patients admitted to seven community hospitals in Michigan, United States, with polymerase chain reaction confirmed diagnosis of COVID-19 from March 10 to April 15, 2020 were analyzed. The primary outcomes of racial disparity in inpatient mortality and intubation were analyzed using descriptive statistics and multivariate regression models.

RESULTS

The study included 336 Black and 408 White patients. Black patients were younger (62.9 ± 15.0 years vs 71.8 ± 16.4, P < .001), had a higher mean body mass index (32.4 ± 8.6 kg/m2 vs 28.8 ± 7.5, P < .001), had higher prevalence of diabetes (136/336 vs 130/408, P = .02), and presented later (6.6 ± 5.3 days after symptom onset vs. 5.4 ± 5.4, P = .006) compared with White patients. Younger Black patients had a higher prevalence of obesity (age <65 years, 69.9%) than older Black patients (age >65 years, 39.2%) and younger White patients (age < 65, 55.1%). Intubation did not reach statistical significance for racial difference (Black patients 61/335 vs. 54/406, P = .08). Mortality was not higher in Black patients (65/335 vs. 142/406 in White patients, odds ratio 0.61, 95% confidence interval: 0.37 to 0.99, 2-sided P = .05) in multivariate analysis, accounting for other risk factors associated with mortality.

CONCLUSIONS

Higher prevalence of obesity and diabetes in young Black populations may be the critical factor driving disproportionate COVID-19 hospitalizations in Black populations. Hospitalized Black patients do not have worse outcomes compared with White patients.

Allograft and Patient Outcomes Between Indigenous and Nonindigenous Kidney Transplant Recipients

BACKGROUND

Kidney transplant outcomes of indigenous Australians are poorer compared with nonindigenous Australians, but it is unknown whether the type of acute rejection differs between these patient groups or whether rejection mediates the effect between ethnicity, death-censored graft failure (DCGF), and death with a functioning graft (DWFG).

METHODS

Biopsy-proven acute rejection (BPAR) rates and types were compared between indigenous and nonindigenous recipients. The associations between ethnicity, BPAR, DCGF, and DWFG were examined using adjusted competing risk analyses, and mediation analysis was conducted to determine whether BPAR mediated the adverse effects between ethnicity and outcomes.

RESULTS

Fifty-seven (9.3%) of 616 patients who have received kidney-only transplants between 2000 and 2010 in Western Australia were indigenous. Compared with nonindigenous recipients, BPAR rates were higher in indigenous recipients (42 versus 74 episodes/100 recipients, P < 0.01), with an excess of antibody-mediated rejections. During a median follow-up of 8 years, indigenous recipients were more likely to experience BPAR, DCGF, and DWFG compared with nonindigenous recipients, with adjusted subdistribution hazard ratio of 1.94 (1.39-2.70), 1.53 (0.85-2.76; P = 0.159), and 2.14 (1.13-4.06; P = 0.020), respectively. Although 70% of the effect between ethnicity and DCGF was mediated by BPAR, no similar association was found for DWFG.

CONCLUSIONS

Indigenous recipients experienced poorer allograft and patient outcomes compared with nonindigenous recipients, with BPAR an important determinant for DCGF. Future research identifying other risk factors and mediators associated with patient survival in indigenous recipients should be considered a priority.

Referral for Kidney Transplantation in Canadian Provinces

BACKGROUND

Patient referral to a transplant facility, a prerequisite for dialysis-treated patients to access kidney transplantation in Canada, is a subjective process that is not recorded in national dialysis or transplant registries. Patients who may benefit from transplant may not be referred.

METHODS

In this observational study, we prospectively identified referrals for kidney transplant in adult patients between June 2010 and May 2013 in 12 transplant centers, and linked these data to information on incident dialysis patients in a national registry.

RESULTS

Among 13,184 patients initiating chronic dialysis, the cumulative incidence of referral for transplant was 17.3%, 24.0%, and 26.8% at 1, 2, and 3 years after dialysis initiation, respectively; the rate of transplant referral was 15.8 per 100 patient-years (95% confidence interval, 15.1 to 16.4). Transplant referral varied more than three-fold between provinces, but it was not associated with the rate of deceased organ donation or median waiting time for transplant in individual provinces. In a multivariable model, factors associated with a lower likelihood of referral included older patient age, female sex, diabetes-related ESKD, higher comorbid disease burden, longer durations (>12.0 months) of predialysis care, and receiving dialysis at a location >100 km from a transplant center. Median household income and non-Caucasian race were not associated with a lower likelihood of referral.

CONCLUSIONS

Referral rates for transplantation varied widely between Canadian provinces but were not lower among patients of non-Caucasian race or with lower socioeconomic status. Standardization of transplantation referral practices and ongoing national reporting of referral may decrease disparities in patient access to kidney transplant.

Validation of Self-Reported Race in a Canadian Provincial Renal Administrative Database

Background:

Administrative data are commonly used to study clinical outcomes in renal disease. Race is an important determinant of renal health delivery and outcomes in Canada but is not validated in most administrative data, and the correlation with census-based definitions of race is unknown.

Objectives:

Validation of self-reported race (SRR) in a Canadian provincial renal administrative database (Patient Records and Outcome Management Information System [PROMIS]) and comparison with the Canadian census categories of race.

Design:

Prospective patient survey study to validate SRR in PROMIS.

Setting:

British Columbia, Canada.

Patients:

Adult patients registered in PROMIS.

Measurements:

Survey SRR was used as gold standard to validate SRR in PROMIS. Self-reported race in PROMIS was compared with census race categories.

Methods:

This is a cross-sectional telephone survey of a random sample of all adults in PROMIS conducted between February 2016 and November 2016. Responders selected a race category from PROMIS and from the Canadian census. Sensitivity (Sn) and specificity (Sp) were calculated with 95% confidence intervals (CIs).

Results:

A total of 21 039 patients met inclusion criteria, 1677 were selected for the survey and 637 participated (38% response rate). There were no differences between the PROMIS, sampled, and responder populations. PROMIS SRR had an accuracy of 95.3% (95% CI: 94.2%-97.0%) when validated against the survey SRR with Sn and Sp ≥90% in all race groups except in Aboriginals (Sn 87.5%). The positive and negative predictive values were ≥95%, except in very low and high–prevalence groups, respectively. The Canadian census had an accuracy of 95.7% (95% CI: 94.4%-97.6%) when validated against PROMIS SRR with Sn and Sp ≥90%. The results did not differ in subgroups based on age, sex, birth outside Canada, or renal group (glomerulonephritis, chronic kidney disease, hemodialysis, peritoneal dialysis, transplant recipients, or live donors).

Limitations:

Analysis of minority groups and lower prevalence groups is limited by sample size. Results may not be generalizable to other administrative databases.

Conclusions:

We have shown high accuracy of PROMIS SRR that validates its use in the secondary analysis of administrative data for research. There is high correlation between PROMIS and census race categories which allows linkage with other data sources that use census-based definitions of race.

Black Ethnicity is Not a Risk Factor for Mortality or Graft Loss After Kidney Transplant in the United Kingdom

OBJECTIVES

There are conflicting reports in the literature regarding outcomes after kidney transplant for patients of black ethnicity. To investigate further, we compared outcomes for black versus white kidney transplant recipients in a single UK transplant center.

MATERIALS AND METHODS

We analyzed 1066 kidney transplant recipients (80 black patients, 986 white patients) within a single-center cohort (2007-2017) in the United Kingdom, with cumulative 4446 patient-year follow-up. Data were electronically extracted from the Department of Health Informatics database for every study recruit, with manual data linkage to the UK Transplant Registry (for graft survival, delayed graft function, and rejection data) and Office for National Statistics (for mortality data). Primary outcomes of interest were graft/patient survival.

RESULTS

Black recipients have increased baseline risk profiles with longer wait times, difficulty in matching, worse HLA matching, more socioeconomic deprivation, and lower rates of living kidney donors. Postoperatively, black versus white recipients had increased risk for delayed graft function (34.3% vs 10.2%; P < .001), increased 1-year rejection (16.7% vs 7.3%; P = .012), higher 1-year creatinine levels (166 vs 138 mmol/L; P = .003), and longer posttransplant length of stay (14.5 vs 9.5 days; P = .020). Although black recipients did not have increased risk of death versus white recipients (10.0% vs 11.0%, respectively; P = .486), they did have increased risk for death-censored graft loss (23.8% vs 11.1%; P = .002). However, in an adjusted Cox regression model, black ethnicity was not associated with increased risk for death-censored graft loss (hazard ratio of 1.209, 95% confidence interval, 0.660-2.216; P = .539).

CONCLUSIONS

Black kidney transplant recipients in the United Kingdom have increased risk of adverse graft-related outcomes due to high-risk baseline variables rather than their black ethnicity per se.

Improving Medication Safety and Cardiovascular Risk Factor Control to Mitigate Disparities in African-American Kidney Transplant Recipients: Design and Methods

There is a lack of data analyzing the influence of cardiovascular disease (CVD) risk factor control on graft survival disparities in African-American kidney transplant recipients. Studies in the general population indicate that CVD risk factor control is poor in African-Americans, leading to higher rates of renal failure and major acute cardiovascular events. However, with the exception of hypertension, there is no data demonstrating similar results within transplant recipients. Recent analyses conducted by our investigator group indicate that CVD risk factors, especially diabetes, are poorly controlled in African-American recipients, which likely impacts graft loss. This study protocol describes a prospective interventional clinical trial with the goal of demonstrating improved medication safety and CVD risk factor control in adult solitary kidney transplant recipients at least one-year post-transplant with a functioning graft. This is a prospective, interventional, 6-month, pharmacist-led and technology enabled study in adult kidney transplant recipients with the goal of improving CVD risk factor outcomes by improving medication safety and patient self-efficacy. This papers describes the issues related to racial disparities in transplant, the details of this intervention and how we expect this intervention to improve CVD risk factor control in kidney transplant recipients, particularly within African-Americans.

Outcomes at 7 years post-transplant in black vs nonblack kidney transplant recipients administered belatacept or cyclosporine in BENEFIT and BENEFIT-EXT

Clinical outcomes are generally worse for black vs nonblack renal allograft recipients. In BENEFIT and BENEFIT-EXT, recipients were randomized to belatacept more intense-based, belatacept less intense-based, or cyclosporine-based immunosuppression. At year 7, belatacept was associated with superior graft survival vs cyclosporine in BENEFIT (recipients of living or standard criteria deceased donor kidneys); belatacept was associated with similar graft survival vs cyclosporine in BENEFIT-EXT (recipients of extended criteria donor kidneys). In both studies, renal function was superior for belatacept-treated vs cyclosporine-treated patients. Seven-year outcomes were examined by race post hoc in each study. The effect of race and treatment on time to death or graft loss was compared using Cox regression. The interaction between treatment and race was also considered. Glomerular filtration rate (GFR) was estimated from months 1 to 84 using a repeated-measures model. In total, 8.3% (55/666) and 13.1% (71/543) of patients in BENEFIT and BENEFIT-EXT, respectively, were black. Time to death or graft loss was similar in blacks and nonblacks. For both subgroups, estimated mean GFR increased over 7 years for belatacept, but declined for cyclosporine. Outcomes were similar in belatacept-treated black and nonblack patients. Due to the small number of black patients, these results must be interpreted with caution.

Genetic predictors of long-term graft function in kidney and pancreas transplant patients

Kidney and pancreas transplantation have helped transform the lives of people with end-stage renal failure and individuals with type 1 diabetes who have poor glycaemic control/severe secondary complications, respectively. Despite an improvement in immunosuppressive regimes, operative techniques and decreased initial rejection rates, there has been little improvement in long-term graft survival rates over the past decade. Whilst limited progress has been made in establishing clinical markers of graft function, several genetic markers of long-term graft function have been identified. These genetic markers have the potential to (i) assist in selecting marginal donor organs for transplantation, (ii) provide better understanding of the mechanisms behind graft loss enabling identification of new, or repurposing, current treatments to extend graft function and (iii) provide a window of opportunity to identify and treat individuals before graft failure has occurred. This review will discuss the different genetic variants screened for a role in predicting transplant longevity, examine their findings and limitations and introduce where the future of genetic research within the transplantation field lies.

Quantifying the Race Stratified Impact of Socioeconomics on Graft Outcomes in Kidney Transplant Recipients

BACKGROUND

Socioeconomic status (SES) is a significant determinant of health outcomes and may be an important component of the causal chain surrounding racial disparities in kidney transplantation. The social adaptability index (SAI) is a validated and quantifiable measure of SES, with a lack of studies analyzing this measure longitudinally or between races.

METHODS

Longitudinal cohort study in adult kidney transplantation transplanted at a single-center between 2005 and 2012. The SAI score includes 5 domains (employment, education, marital status, substance abuse and income), each with a minimum of 0 and maximum of 3 for an aggregate of 0 to 15 (higher score → better SES).

RESULTS

One thousand one hundred seventy-one patients were included; 624 (53%) were African American (AA) and 547 were non-AA. African Americans had significantly lower mean baseline SAI scores (AAs 6.5 vs non-AAs 7.8; P < 0.001). Cox regression analysis demonstrated that there was no association between baseline SAI and acute rejection in non-AAs (hazard ratio [HR], 0.92; 95% confidence interval [95% CI], 0.81-1.05), whereas it was a significant predictor of acute rejection in AAs (HR, 0.89; 95% CI, 0.80-0.99). Similarly, a 2-stage approach to joint modelling of time to graft loss and longitudinal SAI did not predict graft loss in non-AAs (HR, 1.01; 95% CI, 0.28-3.62), whereas it was a significant predictor of graft loss in AAs (HR, 0.23; 95% CI, 0.06-0.93).

CONCLUSIONS

After controlling for confounders, SAI scores were associated with a lower risk of acute rejection and graft loss in AA kidney transplant recipients, whereas neither baseline nor follow-up SAI predicted outcomes in non-AA kidney transplant recipients.

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.

Do outcomes after kidney transplantation differ for black patients in England versus New York State? A comparative, population-cohort analysis

OBJECTIVES

Inferior outcomes for black kidney transplant recipients in the USA may not be generalisable elsewhere. In this population cohort analysis, we compared outcomes for black kidney transplant patients in England versus New York State.

DESIGN

Retrospective, comparative, population cohort study utilising administrative data registries.

SETTINGS AND PARTICIPANTS

English data were derived from Hospital Episode Statistics, while New York State data were derived from Statewide Planning and Research Cooperative System. All adults receiving their first kidney-alone allograft between 2003 and 2013 were eligible for inclusion.

MEASURES

The primary outcome measure was mortality post kidney transplantation (including inhospital death, 30-day mortality and 1-year mortality). Secondary outcome measures included postoperative admission length of stay, risk of rehospitalisation, development of cardiac events, stroke, cancer or fracture and finally transplant rejection/failure. Cox proportional hazards regression was used to investigate relationship between ethnicity, country and outcome.

RESULTS

Black patients comprised 6.5% of the English cohort (n=1215/18 493) and 23.0% of the New York State cohort (n=2660/11 602). Compared with New York State, black kidney transplant recipients in England were more likely younger, male, living-donor kidney recipients and had dissimilar medical comorbidities. Inpatient mortality was not statistically different, but death within 30 days, 1 year or kidney transplant rejection/failure was lower among black patients in England versus black patients in New York State. In adjusted regression analysis, with black ethnicity the reference group, white patients had reduced risk for 30-day mortality (OR 0.62 (95% CI 0.44 to 0.86)) and 1-year mortality (OR 0.79 (95% CI 0.63 to 0.99)) in New York State but no difference was observed in England. Compared with England, black kidney transplant patients in New York State had increased HR for kidney transplant rejection rejection/failure by median follow-up (HR 2.15, 95% CI 1.91 to 2.43).

CONCLUSIONS

Outcomes after kidney transplantation for black patients may not be translatable between countries.

Twenty years of evolving trends in racial disparities for adult kidney transplant recipients

Disparities in outcomes for African American (AA) kidney transplant recipients have persisted for 40 years without a comprehensive analysis of evolving trends in the risks associated with this disparity. Here we analyzed U.S. transplant registry data, which included adult Caucasian or AA solitary kidney recipients undergoing transplantation between 1990 and 2009 comprising 202,085 transplantations. During this 20-year period, the estimated rate of 5-year graft loss decreased from 27.6% to 12.8%. Notable trends in baseline characteristics that significantly differed by race over time included the following: increased prevalence of diabetes from 2001 to 2009 in AAs (5-year slope difference: 3.4%), longer time on the waiting list (76.5 more days per 5 years in AAs), fewer living donors in AAs from 2003 to 2009 (5-year slope difference: -3.36%), more circulatory death donors in AAs from 2000-09 (5-year slope difference: 1.78%), and a slower decline in delayed graft function in AAs (5-year slope difference: 0.85%). The absolute risk difference between AAs and Caucasians for 5-year graft loss significantly declined over time (-0.92% decrease per 5 years), whereas the relative risk difference actually significantly increased (3.4% increase per 5 years). These results provide a mixed picture of both promising and concerning trends in disparities for AA kidney transplant recipients. Thus, although the disparity for graft loss has significantly improved, equity is still far off, and other disparities, including living donation rates and delayed graft function rates, have widened during this time.

Impact of Cardiovascular Risk Factors on Graft Outcome Disparities in Black Kidney Transplant Recipients

Although outcome inequalities for non-Hispanic black (NHB) kidney transplant recipients are well documented, there is paucity in data assessing the impact of cardiovascular disease (CVD) risk factors on this disparity in kidney transplantation. This was a longitudinal study of a national cohort of veteran kidney recipients transplanted between January 2001 and December 2007. Data included baseline characteristics acquired through the United States Renal Data System linked to detailed clinical follow-up information acquired through the Veterans Affairs electronic health records. Analyses were conducted using sequential multivariable modeling (Cox regression), incorporating blocks of variables into iterative nested models; 3139 patients were included (2095 non-Hispanic whites [66.7%] and 1044 NHBs [33.3%]). NHBs had a higher prevalence of hypertension (100% versus 99%; P<0.01) and post-transplant diabetes mellitus (59% versus 53%; P<0.01) with reduced control of hypertension (blood pressure <140/90 60% versus 69%; P<0.01), diabetes mellitus (A1c <7%, 35% versus 47%; P<0.01), and low-density lipoprotein (<100 mg/dL, 55% versus 61%; P<0.01). Adherence to medications used to manage CVD risk was significantly lower in NHBs. In the fully adjusted models, the independent risk of graft loss in NHBs was substantially reduced (unadjusted hazard ratio, 2.00 versus adjusted hazard ratio, 1.49). CVD risk factors and control reduced the influence of NHB race by 9% to 18%. Similar trends were noted for mortality, and estimates were robust across in sensitivity analyses. These results demonstrate that NHB kidney transplant recipients have significantly higher rates of CVD risk factors and reduced CVD risk control. These issues are likely partly related to medication nonadherence and meaningfully contribute to racial disparities for graft outcomes.

Influence of municipality-level mean income on access to aortic valve surgery: a cross-sectional observational study under Japan's universal health-care coverage

BACKGROUND

Universal health-care coverage has attracted the interest of policy makers as a way of achieving health equity. However, previous reports have shown that despite universal coverage, socioeconomic disparity persists in access to high-tech invasive care, such as cardiac treatment. In this study, we aimed to investigate the association between socioeconomic status and care of aortic stenosis in the context of Japan's health-care system, which is mainly publicly funded.

METHODS

We chose aortic stenosis in older people as a target because such patients are likely to be affected by socioeconomic disparity. Using a large Japanese claim-based inpatient database, we identified 12,893 isolated aortic stenosis patients aged over 65 years who were hospitalized between July 2010 and March 2012. Municipality socioeconomic status was represented by the mean household income of the patients' residential municipality, categorized into quartiles. The likelihood of undergoing aortic valve surgery and in-hospital mortality was regressed against socioeconomic status level with adjustments for hospital volume, regional number of cardiac surgeons per 1 million population, and patients' clinical status.

RESULTS

We found no significant differences between the highest and lowest quartile groups in surgical indication (odds ratio, 0.84; 95% confidence interval, 0.69-1.03) or in-hospital mortality (1.00; 0.68-1.48). Hospital volume was significantly associated with lower postoperative mortality (odds ratio of the highest volume tertile to the lowest, 0.49; 0.34-0.71).

CONCLUSIONS

Under Japan's current universal health-care coverage, municipality socioeconomic status did not appear to have a systematic relationship with either treatment decision for surgical intervention or postoperative survival following aortic valve surgery among older patients. Our results imply that universal health-care coverage with high publicly funded coverage offers equal access to high-tech cardiovascular care.

Socioeconomic disparities in mortality after cancer surgery: failure to rescue

IMPORTANCE

Disparities in operative mortality due to socioeconomic status (SES) have been consistently demonstrated, but the mechanisms underlying this disparity are not well understood.

OBJECTIVE

To determine whether variations in failure to rescue (FTR) contribute to socioeconomic disparities in mortality after major cancer surgery.

DESIGN, SETTING, AND PARTICIPANTS

We performed a retrospective cohort study using the Medicare Provider Analysis and Review File and the Medicare Denominator File. A summary measure of SES was created for each zip code using 2000 US Census data linked to residence. Multivariable logistic regression was used to examine the influence of SES on rates of FTR, and fixed-effects hierarchical regression was used to evaluate the extent to which disparities could be attributed to differences among hospitals. A total of 596,222 patients undergoing esophagectomy, pancreatectomy, partial or total gastrectomy, colectomy, lung resection, and cystectomy for cancer from 2003 through 2007 were studied.

MAIN OUTCOMES AND MEASURES

Operative mortality, postoperative complications, and FTR (case fatality after ≥1 major complication).

RESULTS

Patients in the lowest quintile of SES had mildly increased rates of complications (25.6% in the lowest quintile vs 23.8% in the highest quintile, P = .003), a larger increase in mortality (10.2% vs 7.7%, P = .0009), and the greatest increase in rates of FTR (26.7% vs 23.2%, P = .007). Analysis of hospitals revealed a higher FTR rate for all patients (regardless of SES) at centers treating the largest proportion of patients with low SES. The adjusted odds ratios (95% CIs) of FTR according to SES ranged from 1.04 (0.95-1.14) for gastrectomy to 1.45 (1.21-1.73) for pancreatectomy. Additional adjustment for hospital effect nearly eliminated the disparity observed in FTR across levels of SES.

CONCLUSIONS AND RELEVANCE

Patients in the lowest quintile of SES have significantly increased rates of FTR. This finding appears to be in part a function of the hospital where patients with low SES are treated. Future efforts to improve socioeconomic disparities should concentrate on hospital processes and characteristics that contribute to successful rescue.

Survival and hospitalization for intensive home hemodialysis compared with kidney transplantation

Canadian patients receiving intensive home hemodialysis (IHHD; ≥16 hours per week) have survival comparable to that of deceased donor kidney transplant recipients in the United States, but a comparison with Canadian kidney transplant recipients has not been conducted. We conducted a retrospective cohort study of consecutive, adult IHHD patients and kidney transplant recipients between 2000 and 2011 at a large Canadian tertiary care center. The primary outcome was time-to-treatment failure or death for IHHD patients compared with expanded criteria, standard criteria, and living donor recipients, and secondary outcomes included hospitalization rate. Treatment failure was defined as a permanent switch to an alternative dialysis modality for IHHD patients, and graft failure for transplant recipients. The cohort comprised 173 IHHD patients and 202 expanded criteria, 642 standard criteria, and 673 living donor recipients. There were 285 events in the primary analysis. Transplant recipients had a reduced risk of treatment failure/death compared with IHHD patients, with relative hazards of 0.45 (95% confidence interval [95% CI], 0.31 to 0.67) for living donor recipients, 0.39 (95% CI, 0.26 to 0.59) for standard criteria donor recipients, and 0.42 (95% CI, 0.26 to 0.67) for expanded criteria donor recipients. IHHD patients had a lower hospitalization rate in the first year of treatment compared with standard criteria donor recipients and in the first 3 months of treatment compared with living donor and expanded criteria donor recipients. In this cohort, kidney transplantation was associated with superior treatment and patient survival, but higher early rates of hospitalization, compared with IHHD.

Significant racial differences in the key factors associated with early graft loss in kidney transplant recipients

BACKGROUND

There is continued and significant debate regarding the salient etiologies associated with graft loss and racial disparities in kidney transplant recipients.

METHODS

This was a longitudinal cohort study of all adult kidney transplant recipients, comparing patients with early graft loss (<5 years) to those with graft longevity (surviving graft with at least 5 years of follow-up) across racial cohorts [African-American (AA) and non-AA] to discern risk factors.

RESULTS

524 patients were included, 55% AA, 151 with early graft loss (29%) and 373 with graft longevity (71%). Consistent within both races, early graft loss was significantly associated with disability income [adjusted odds ratio (AOR) 2.2, 95% CI 1.1-4.5], Kidney Donor Risk Index (AOR 3.2, 1.4-7.5), rehospitalization (AOR 2.1, 1.0-4.4) and acute rejection (AOR 4.4, 1.7-11.6). Unique risk factors in AAs included Medicare-only insurance (AOR 8.0, 2.3-28) and BK infection (AOR 5.6, 1.3-25). Unique protective factors in AAs included cardiovascular risk factor control: AAs with a mean systolic blood pressure <150 mm Hg had 80% lower risk of early graft loss (AOR 0.2, 0.1-0.7), while low-density lipoprotein <100 mg/dl (AOR 0.4, 0.2-0.8), triglycerides <150 mg/dl (AOR 0.4, 0.2-1.0) and hemoglobin A1C <7% (AOR 0.2, 0.1-0.6) were also protective against early graft loss in AA, but not in non-AA recipients.

CONCLUSIONS

AA recipients have a number of unique risk factors for early graft loss, suggesting that controlling cardiovascular comorbidities may be an important mechanism to reduce racial disparities in kidney transplantation.

Outcomes in ethnic minority renal transplant recipients receiving everolimus versus mycophenolate: comparative risk assessment results from a pooled analysis

Background

Everolimus (EVR) has demonstrated good efficacy after renal transplantation. Racial disparities in clinical outcomes after de novo renal transplantation are well documented; whether the efficacy of EVR varies based on recipient ethnicity is unknown. We conducted a comparative risk assessment of EVR by ethnicity.

Methods

Data on 2004 renal transplant recipients from three EVR studies were pooled to identify the impact of ethnicity on efficacy outcomes across EVR dosing groups and control groups. Ethnic groups compared were African Americans, non-U.S. blacks, Asians, Hispanics, and Caucasians. EVR groups received either 1.5 or 3 mg per day, with either standard-dose cyclosporine or reduced-dose cyclosporine. Control groups received mycophenolic acid (MPA) with standard-dose cyclosporine. Composite efficacy failure endpoint was graft loss, death, biopsy-proven acute rejection, or lost to follow-up. Adjusted odds ratios were calculated using a logistic regression model.

Results

The proportion of renal transplant recipients who met the composite endpoint was African Americans (46%), non-U.S. black (35%), Caucasian (31%), Hispanic (28%), and Asian (25%). The odds of meeting the composite endpoint were significantly (P=0.0001) greater for African Americans versus Caucasians but did not differ among the other ethnic groups (ethnic groups were only compared with Caucasians). EVR and MPA were associated with similar efficacy among each of the ethnic groups.

Conclusion

In this pooled data analysis in more than 2000 renal transplant recipients, EVR versus MPA resulted in similar composite endpoint incidence events across ethnicities. Consistent with previously published data, African Americans had poorer clinical outcomes. EVR is efficacious regardless of ethnicity.

Kidney graft survival in Europe and the United States: strikingly different long-term outcomes

BACKGROUND

Kidney graft survival has never been systematically compared between Europe and the United States.

METHODS

Applying period analysis to first deceased-donor (DD) and living-donor kidney grafts from the United Network for Organ Sharing/Organ Procurement and Transplantation Network for the United States and the Collaborative Transplant Study for Europe, we compared overall and age-specific 1-, 5-, and 10-year graft survival for Europeans and white, African, and Hispanic Americans for the 2005 to 2008 period. A Cox regression model was used to adjust for differences in patient characteristics.

RESULTS

For the 2005 to 2008 period, 1-year survival for DD grafts was equal (91%) between Europeans and white and Hispanic Americans, whereas it was slightly lower for African Americans (89%). In contrast, overall 5- and 10-year graft survival rates were considerably higher for Europe (77 and 56%, respectively) than for any of the three U.S. populations (whites, 71 and 46%, Hispanic, 73 and 48%, and African American, 62 and 34%). Differences were largest for recipient ages 0 to 17 and 18 to 29 and generally increased beyond 3 to 4 years after transplantation. Survival patterns for living-donor grafts were similar as those seen for DD grafts. Adjusted hazard ratios for graft failure in United Network for Organ Sharing white Americans ranged between 1.5 and 2.3 (all P<0.001) for 2 to 5 years after transplantation, indicating that lower graft survival is not explained by differences in baseline patient characteristics.

CONCLUSIONS

Long-term kidney graft survival rates are markedly lower in the United States compared with Europe. Identifying actionable factors explaining long-term graft survival differences between Europe and the United States is a high priority for improving long-term graft survival.

Lack of listing status awareness: results of a single-center survey of hemodialysis patients

This study surveyed hemodialysis patients in an urban transplant center serving a predominantly African American population to identify existing and potential barriers to transplantation. The survey used the Dialysis Patient Transplant Questionnaire (DPTQ) to collect self-reported data including interest in a deceased donor kidney transplant and self-reported listing status. We compared patients' survey data to their UNOS listing and computerized medical record at time of interview. Among the 116 patients surveyed, 83 (71.6%) reported interest in a deceased donor kidney transplant. Eighteen (52.9%) of the 34 patients undergoing pretransplantation workup were unaware of their true listing status, and 88.9% of these patients mistakenly believed they were wait listed. All of the patients who mistakenly thought they were listed were undergoing workup. Finding that a significant number of hemodialysis patients who want a deceased donor kidney transplant mistakenly think they are listed when they are not is a documentable deficiency in communication and a potential barrier to transplantation. The finding highlights a correctable problem in communication and work flow that could help to improve transplant center effectiveness. It also reveals that self-reported waiting list status significantly overestimated true waiting list status for our patients at time of interview.

Racial and ethnic disparities in kidney transplantation

Success of renal transplantation, as a viable alternative to dialysis, has been tempered by long-standing racial disparities. Ethnic minorities have less access to transplantation, are less likely to be listed for transplantation, and experience a higher rate of graft failure. Reasons for the existing racial disparities at various stages of the transplantation process are complex and multi-factorial. They include a combination of behavioral, social, environmental, and occupational factors, as well as potential intended or unintended discrimination within the healthcare system. Immunologic factors such as human leukocyte antigen matching, composition of the organ donor pool, and patient immune response, all of which affect post-transplantation graft rejection rates and patient survival, also contribute to health disparities between ethnic groups.

Overview of the Canadian pediatric end-stage renal disease database

BACKGROUND

Performing clinical research among pediatric end-stage renal disease patients is challenging. Barriers to successful initiation and completion of clinical research projects include small sample sizes and resultant limited statistical power and lack of longitudinal follow-up for hard clinical end-points in most single center studies.

DESCRIPTION

Existing longitudinal organ failure disease registry and administrative health datasets available within a universal access health care system can be used to study outcomes of end-stage renal disease among pediatric patients in Canada. To construct the Canadian Pediatric End-Stage Renal Disease database, registry data were linked to administrative health data through deterministic linkage techniques creating a research database which consists of socio-demographic variables, clinical variables, all-cause hospitalizations, and relevant outcomes (death and renal allograft loss) for this patient population. The research database also allows study of major cardiovascular events using previously validated administrative data definitions.

CONCLUSION

Organ failure registry linked to health administrative data can be a powerful tool to perform longitudinal studies in pediatric end-stage renal disease patients. The rich clinical and demographic information found in this database will facilitate study of important medical and non-medical risk factors for death, graft loss and cardiovascular disease among pediatric end-stage renal disease patients.

Disparities in kidney transplant outcomes: a review

Sociocultural and socioeconomic disparities in graft survival, graft function, and patient survival in adult kidney transplant recipients are reviewed. Studies consistently document worse outcomes for black patients, patients with low income, and patients with less education, whereas better outcomes are reported in Hispanic and Asian kidney transplant recipients. However, the distinct roles of racial/ethnic versus socioeconomic factors remain unclear. Attention to potential pathways contributing to disparities has been limited to immunologic and nonimmunologic factors, for which the mechanisms have yet to be fully illuminated. Interventions to reduce disparities have focused on modifying immunosuppressant regimens. Modifying access to care and health care funding policies for immunosuppressive medication coverage also are discussed. The implementation of culturally sensitive approaches to the care of transplant candidates and recipients is promising. Future research is needed to examine the mechanisms contributing to disparities in graft survival and ultimately to intervene effectively.

Black renal transplant recipients have poorer long-term graft survival than CYP3A5 expressers from other ethnic groups

BACKGROUND

African American transplant recipients have poorer long-term outcomes than Caucasian Americans. This difference was not found in French patients, suggesting socialized medicine overcame this disparity. It has also been hypothesized that the difference relates to the higher prevalence of Black individuals who express the metabolic enzyme cytochrome P4503A5 (CYP3A5), with consequent altered handling of immunosuppressive drugs.

METHODS

Records of 555 (50 Black; 505 non-Black) sequential renal transplant recipients from a single UK centre were analysed.

RESULTS

Outcomes were significantly worse for Black patients: death-censored graft survival (5-year 66% versus 87%, P = 0.001); halving of year one estimated glomerular filtration rate (mean 8.8 versus 10.8 years, P = 0.008); first-year graft loss (12% versus 3.8%, P = 0.02); and death-censored graft survival in patients surviving the first year with functioning grafts (5-year 77% versus 94%, P = 0.02). Death-censored 5-year graft survival was poorer in Black CYP3A5 expressers than in non-Black CYP3A5 expressers (62% versus 93%, P = 0.002). Following multivariate analysis, the Black group demonstrated poorer graft survival as compared to the non-Black group (hazard ratio 0.46, 95% CI 0.25-0.85, P = 0.002). In a subgroup of genotyped transplant recipients, ethnicity (hazard ratio 0.31, 95% CI 0.15-0.64, P = 0.002), and not CYP3A5 expresser status, persists as an independent risk factor for graft survival following multivariate analysis.

CONCLUSION

In this cohort of patients with socialized medicine, Black recipients had poorer long-term outcomes than individuals from other ethnic groups. This was independent of CYP3A5 expresser status.