Racial/Ethnic Disparity in Kidney Transplantation Outcomes: Influence of Donor andRecipient Characteristics

Identifying when racial and ethnic disparities arise along the continuum of transplant care: a national registry study

Background

Fewer minoritized patients with end-stage kidney disease (ESKD) receive kidney transplantation (KT); efforts to mitigate disparities have thus far failed. Pinpointing the specific stage(s) within the transplant care continuum (being informed of KT options, joining the waiting list, to receiving KT) where disparities emerge among each minoritized population is pivotal for achieving equity. We therefore quantified racial and ethnic disparities across the KT care continuum.

Methods

We conducted a retrospective cohort study (2015-2020), with follow-up through 12/10/2021. Patients with incident dialysis were identified using the US national registry data. The exposure was race and ethnicity (Asian, Black, Hispanic, and White). We used adjusted modified Poisson regression to quantify the adjusted prevalence ratio (aPR) of being informed of KT, and cause-specific hazards models to calculate adjusted hazard ratios (aHR) of listing, and transplantation after listing.

Findings

Among 637,951 adults initiating dialysis, the mean age (SD) was 63.8 (14.6), 41.8% were female, 5.4% were Asian, 26.3% were Black, 16.6% were Hispanic, and 51.7% were White (median follow-up in years [IQR]:1.92 [0.97-3.39]). Black and Hispanic patients were modestly more likely to be informed of KT (Black: aPR = 1.02, 95% confidence interval [CI]:1.01-1.02; Hispanic: aPR = 1.03, 95% CI: 1.02-1.03) relative to White patients. Asian patients were more likely to be listed (aHR = 1.18, 95% CI: 1.15-1.21) but less likely to receive KT (aHR = 0.56, 95% CI: 0.54-0.58). Both Black and Hispanic patients were less likely to be listed (Black: aHR = 0.87, 95% CI: 0.85-0.88; Hispanic: aHR = 0.85, 95% CI: 0.85-0.88) and receive KT (Black: aHR = 0.61, 95% CI: 0.60-0.63; Hispanic: aHR = 0.64, 95% CI: 0.63-0.66).

Interpretation

Improved characterization of the barriers in KT access specific to each racial and ethnic group, and the interventions to address these distinct challenges throughout the KT care continuum are needed; our findings identify specific stages most in need of mitigation.

Funding

National Institutes of Health.

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.

Racial disparities in cardiac transplantation: Chronological perspective and outcomes

BACKGROUND

The objective of this study was to evaluate annual heart transplant volumes and 3-year post-transplant outcomes since establishment of United Network for Organ Sharing (UNOS) database stratified by race.

METHODS

The UNOS thoracic transplant database was evaluated for adult patients since 1987. The available database was then stratified by Race: Black, White and Other and era of transplant: group 1(1987-1991), group 2(1992-1996), group 3(1997-2001), group 4(2002-2006), group 5(2007-2011), group 6(2012-2016) and group 7(2017 and later). Demographic and clinical factors were evaluated.

RESULTS

A total of 105,266 adults have been listed since 1987 and 67,824 have been transplanted. Of the transplanted patients 11,235 were Black, 48,786 White and 6803 were of Other race. The proportion of Black patients listed increased from 7% in 1987 to 13.4% in 1999 and 25% in 2019 and those transplanted increased from 5% in 1987 to 13.4% in 2001 and 26% in 2019. The survival of Black patients gradually improved.

CONCLUSION

Historically, fewer Black patients received cardiac transplantation however, their access gradually improved over the years and account for over 25% of cardiac transplantations performed in recent years. The historically poor survival of Black patients has recently improved and became comparable to the rest.

Simultaneous pancreas‐kidney transplantation in Caucasian versus African American patients: Does recipient race influence outcomes?

The influence of African American (AA) recipient race on outcomes following simultaneous pancreas‐kidney transplantation (SPKT) is uncertain.

Multivariate Longitudinal Assessment of Kidney Function Outcomes on Graft Survival after Kidney Transplantation Using Multivariate Joint Modeling Approach: A Retrospective Cohort Study

Background

The performance of a transplanted kidney is evaluated by monitoring variations in the value of the most important markers. These markers are measured longitudinally, and their variation is influenced by other factors. The simultaneous use of these markers increases the predictive power of the analytical model. This study aimed to determine the simultaneous longitudinal effect of serum creatinine and blood urea nitrogen (BUN) markers, and other risk factors on allograft survival after kidney transplantation.

Methods

In a retrospective cohort study, the medical records of 731 renal transplant patients, dated July 2000 to December 2013, from various transplant centers in Mashhad (Iran) were examined. Univariate and multivariate joint models of longitudinal and survival data were used, and the results from both models were compared. The R package joineRML was used to implement joint models. P values <0.05 were considered statistically significant.

Results

Results of the multivariate model showed that allograft rejection occurred more frequently in patients with elevated BUN levels (HR=1.68, 95% CI: 1.24-2.27). In contrast, despite a positive correlation between serum creatinine and allograft rejection (HR=1.49, 95% CI: 0.99-2.22), this relationship was not statistically significant.

Conclusion

Results of the multivariate model showed that longitudinal measurements of BUN marker play a more important role in the investigation of the allograft rejection.

Graft and Patient Survival Rates in Kidney Transplantation, and Their Associated Factors: A Systematic Review and Meta-Analysis

BACKGROUND

End-Stage Renal Disease (ESRD) is an irreversible impairment of kidney function that leads to permanently dependent on alternative therapies such as hemodialysis, peritoneal dialysis, and renal transplantation. This study aimed to systematically investigate the survival rate of patients with renal transplantation, graft, and its related factors in Iran.

METHODS

This systematic review and meta-analysis drew on articles indexed in six international and one internal databases (Medline/PubMed, ProQuest, Scopus, Embase, SID, and Web of knowledge) until Nov 2020. The reporting of the present study was performed in terms of PRISMA statement. All analyzes were performed using the STATA software.

RESULTS

Overall, 367 titles from 6 databases were evaluated of which 86 articles met the inclusion criteria. According to the random model, the graft survival rate at one, three, five, and 10 years were 92.48%, 85.08%, 79.96% and 68.15% respectively. Additionally, the patient survival rates at one, three, five, and 10 years were 91.27%, 86.46%, 81.17% and 78.15% respectively. There was a significant relationship between the age recipient and three-year graft survival rate (P=0.021). Additionally, there was an inverse and significant relationship between the donor age and 10-year patient survival rate (P=0.011).

CONCLUSION

The patient and graft survival in transplanted kidney patients is comparable with most developed countries.

CMV high-risk status and posttransplant outcomes in kidney transplant recipients treated with belatacept

INTRODUCTION

Cytomegalovirus (CMV) remains associated with poor outcomes after kidney transplantation (kTx). The impact of belatacept on CMV infection remains understudied. In this study, we assessed the impact of belatacept on patient and graft survivals.

METHODS

CMV seronegative kTx recipients were included. Patient and graft survival were studied using Kaplan-Meier method, log-rank test. Cox models were used to compare outcomes by CMV risk and immunosuppressive regimen. Incidence and persistence of CMV viremia under belatacept vs tacrolimus were compared.

RESULTS

Among 308 CMV seronegative recipients, 168 CMV high-risk and 203 belatacept-treated patients were included. High-risk CMV status was associated with lower patient survival and graft survival. Among the CMV high-risk group, patients treated with belatacept presented a higher incidence of CMV viremia, a higher rate of first-line treatment failure and a longer time to virus clearance. They had a nonsignificant trend toward a lower graft survival.

CONCLUSION

Belatacept-based maintenance immunosuppression is associated with an increased risk of CMV primary-infection and a prolonged course of viral replication in CMV high-risk patients. Further studies are needed to confirm the nonsignificant trend towards a lower graft survival in CMV high-risk patients treated with belatacept and whether it is explained by the higher risk of CMV reactivation and infection.

Progress in research of enhanced recovery after surgery and surgery related differences

Enhanced recovery after surgery (ERAS) refers to the use of standardized, multimodal perioperative strategies to reduce physiological stress and organ dysfunction caused by surgery. Since the ERAS concept was put forward, it has been widely respected in the surgical field. Its benefits in the surgical field for the vast majority of patients, medical staff and healthcare systems are obvious. However, for some specific people undergoing surgery, the benefits are not certain, which is the so-called surgery-related differences. This article analyzes recent studies of different surgical fields related to surgical-related differences in different ethnic groups, reviews a large number of positive effects of the implementation of ERAS on surgical-related differences, and elaborates its possible mechanism. It is finally concluded that ERAS, a standardized model for resolving surgical-related differences, should become the gold standard for surgical perioperative management.

Racial/Ethnic Differences in the Association Between Hospitalization and Kidney Transplantation Among Waitlisted End-Stage Renal Disease Patients

BACKGROUND

Even after placement on the deceased donor waitlist, there are racial disparities in access to kidney transplant. The association between hospitalization, a proxy for health while waitlisted, and disparities in kidney transplant has not been investigated.

METHODS

We used United States Renal Data System Medicare-linked data on waitlisted end-stage renal disease patients between 2005 and 2009 with continuous enrollment in Medicare Parts A & B (n = 24 581) to examine the association between annual hospitalization rate and odds of receiving a deceased donor kidney transplant. We used multilevel mixed effects models to estimate adjusted odds ratios, controlling for individual-, transplant center-, and organ procurement organization-level clustering.

RESULTS

Blacks and Hispanics were more likely than whites to be hospitalized for circulatory system or endocrine, nutritional, and metabolic diseases (P < 0.001). After adjustment, compared with individuals not hospitalized, patients who were hospitalized frequently while waitlisted were less likely to be transplanted (>2 vs 0 hospitalizations/year adjusted odds ratios = 0.57; P < 0.001). Though blacks and Hispanics were more likely to be hospitalized than whites (P < 0.001), adjusting for hospitalization did not change estimated racial/ethnic disparities in kidney transplantation.

CONCLUSIONS

Individuals hospitalized while waitlisted were less likely to receive a transplant. However, hospitalization does not account for the racial disparity in kidney transplantation after waitlisting.

Understanding the influence of ethnicity and socioeconomic factors on graft and patient survival after kidney transplantation

BACKGROUND

Studies on the influence of socioeconomic factors and ethnicity on the results of kidney transplantation have led to various outcomes. In this study, we analyzed the influence of a combination of these factors on graft and patient survival in a population of kidney transplant recipients.

METHODS

This retrospective study included all 1,338 patients who received a kidney transplant between 2000 and 2011 (825 living, 513 deceased donor transplantations). Both clinical and socioeconomic variables were studied. Clinical variables were recipient age, gender, ethnicity, original disease, maximum and current panel reactive antibodies, ABO blood type, retransplants, pretreatment, time on dialysis, comorbidity, transplant year, total number of HLA mismatches, donor type (living or deceased), age and gender, and calcineurin inhibitor treatment. Each recipient's postal code was linked to a postal code area information database to extract information on housing value, income, percentage non-Europeans in the area, and urbanization level.

RESULTS

In multivariable analysis, graft survival censored for death was significantly influenced by recipient age, maximum panel reactive antibodies, HLA mismatches, donor type, donor age, and calcineurin inhibitor treatment. Patient survival was significantly influenced by recipient age, comorbidity, transplant year, and donor type. Socioeconomic factors and ethnicity did not have a significant influence on graft and patient survival.

CONCLUSIONS

Though ethnicity and socioeconomic factors do not influence survival after kidney transplantation, the favorable influence of living donor type is of paramount importance. As non-Europeans and patients with unfavorable socioeconomic variables less often receive a living donor kidney transplant, their survival may be unfavorable after all.

Center-level factors and racial disparities in living donor kidney transplantation

BACKGROUND

On average, African Americans attain living donor kidney transplantation (LDKT) at decreased rates compared with their non-African American counterparts. However, center-level variations in this disparity or the role of center-level factors is unknown.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

247,707 adults registered for first-time kidney transplants from 1995-2007 as reported by the Scientific Registry of Transplant Recipients.

PREDICTORS

Patient-level factors (age, sex, body mass index, insurance status, education, blood type, and panel-reactive antibody level) were adjusted for in all models. The association of center-level characteristics (number of candidates, transplant volume, LDKT volume, median time to transplant, percentage of African American candidates, percentage of prelisted candidates, and percentage of LDKT) and degree of racial disparity in LDKT was quantified.

OUTCOMES

Hierarchical multivariate logistic regression models were used to derive center-specific estimates of LDKT attainment in African American versus non-African American candidates.

RESULTS

Racial parity was not seen at any of the 275 transplant centers in the United States. At centers with the least racial disparity, African Americans had 35% lower odds of receiving LDKT; at centers with the most disparity, African Americans had 76% lower odds. Higher percentages of African American candidates (interaction term, 0.86; P = 0.03) and prelisted candidates (interaction term, 0.80; P = 0.001) at a given center were associated with increased racial disparity at that center. Higher rates of LDKT (interaction term, 1.25; P < 0.001) were associated with less racial disparity.

LIMITATIONS

Some patient-level factors are not captured, including a given patient's pool of potential donors. Geographic disparities in deceased donor availability might affect LDKT rates. Center-level policies and practices are not captured.

CONCLUSIONS

Racial disparity in attainment of LDKT exists at every transplant center in the country. Centers with higher rates of LDKT attainment for all races had less disparity; these high-performing centers might provide insights into policies that might help address this disparity.

Long-term survival of living donor renal transplants: A single center study

Kidney transplantation is the treatment of choice for end-stage renal disease. The aim of this study was to determine the ten-year graft survival rate of renal transplantation in patients who have been transplanted from live donors. This is a historical cohort study designed to determine the organ survival rate after kidney transplantation from live donor during a 10-year period (from March 1999 to March 2009) on 843 patients receiving kidney transplant in the transplantation center of Namazi hospital in Shiraz, Iran. Kaplan-Meier method was used to determine the survival rate, log-rank test was used to compare survival curves, and Cox proportional hazard model was used to multivariate analysis. Mean follow-up was 53.07 ± 34.61 months. Allograft survival rates at 1, 3, 5, 7, and 10 years were 98.3, 96.4, 92.5, 90.8, and 89.2%, respectively. Using Cox proportional hazard model, the age and gender of the donors along with the creatinine level of the patients at discharge were shown to have a significant influence on survival. The 10-year graft survival rate of renal transplantation from living donor in this center is 89.2%, and graft survival rate in our cohort is satisfactory and comparable with reports from large centers in the world.

Gene polymorphism of vascular endothelial growth factor -1154 G>A is associated with hypertensive nephropathy in a Hispanic population

The aim of this study was to determine the association between hypertensive nephropathy and gene polymorphisms of vascular endothelial growth factor (VEGF) in a self-reported Hispanic patient group. A total of 155 Hispanic living kidney donors as controls and a total of 86 Hispanic kidney transplant patients, whose renal failure was attributed to hypertensive nephropathy after ruling out diabetes mellitus or other causes, were genotyped for four different single nucleotide polymorphisms of VEGF: -2578 C>A (rs699947), -1154 G>A (rs1570360), -460 C>T (rs833061), and +936 C>T (rs3025039). The homozygous mutant type (AA) of VEGF -1154 G>A (rs1570360) was found with significantly higher frequency in the hypertensive nephropathy patients than in controls. On the other hand, homozygous wild type (GG) was found less frequently in the hypertensive nephropathy patient group than in the control group. Linkage disequilibrium (LD) analyses revealed a high degree of LD among VEGF -2578 C>A (rs699947), VEGF -1154 G>A (rs1570360), and VEGF -460 C>T (rs833061). The haplotype analysis revealed that two haplotypes, CGTC and CATC (in the order of VEGF -2578 C>A (rs699947), -1154 G>A (1570360), -460 C>T (rs833061), and +936 C>T (3025039)), were significantly associated with hypertensive nephropathy in Hispanic patients. Hence, the -1154 G>A polymorphism (rs1570360) and two haplotypes (CGTC and CATC) of VEGF appear to be associated with hypertensive nephropathy in Hispanic patients who developed end-stage renal disease requiring kidney transplant.

Influence of recipient race on the outcome of simultaneous pancreas and kidney transplantation

Racial differences on the outcome of simultaneous pancreas and kidney (SPK) transplantation have not been well studied. We compared mortality and graft survival of African Americans (AA) recipients to other racial/ethnic groups (non-AA) using the national data. We studied a total of 6585 adult SPK transplants performed in the United States between January 1, 2000 and December 31, 2007. We performed multivariate logistic regression analyses to determine risk factors associated with early graft failure and immune-mediated late graft loss. We used conditional Kaplan-Meier survival and multivariate Cox regression analyses to estimate late death-censored kidney and pancreas graft failure and death between the groups. Although there was no racial disparity in the first 90 days, AA patients had 38% and 47% higher risk for late death-censored kidney and pancreas graft failure, respectively (p = 0.006 and 0.001). AA patients were twice more likely to lose the kidney and pancreas graft due to rejection (OR 2.31 and 1.86, p = 0.002 and 0.008, respectively). Bladder pancreas drainage was associated with inferior patient survival (HR 1.42, 95% CI 1.15, 1.75, p = 0.001). In the era of modern immunosuppression, AA SPK transplant patients continue to have inferior graft outcome. Additional studies to explore the mechanisms of such racial disparity are warranted.