The End of Racial Disparities in Kidney Transplantation? Not So Fast!

HLA B eplet mismatches in the context of delayed graft function and low tacrolimus trough levels are risk factors influencing the generation of de novo donor-specific antibodies and acute rejection in the early stage after kidney transplantation

BACKGROUND

De novo donor-specific antibody (dnDSA) generation and acute rejection (AR) are the main factors affecting long-term graft survival. This study aims to investigate human leukocyte antigen (HLA) eplet mismatching (MM), delayed graft function (DGF), and tacrolimus (TAC) trough levels on the occurrence of dnDSA and AR in the early stages after kidney transplantation (KT).

METHODS

This retrospective study included 526 cases of deceased donation KT. The effects of DGF, HLA eplet MM, and TAC trough levels on dnDSA and AR occurrence were analyzed with logistic regression analysis.

RESULTS

Multivariate logistic regression analysis showed the independent risk factor of dnDSA generation was HLA B eplet MM (OR: 1.201, 95% CI: 1.007-1.431, P = 0.041). The independent risk factors of AR occurrence include DGF (OR: 4.045, 95% CI: 1.047-15.626, P = 0.043), HLA B eplet MM (OR: 1.090, 95% CI: 1.000-1.187, P = 0.050), and TAC trough levels at 12 months (OR: 0.750, 95% CI: 565-0.997, P = 0.048). HLA B eplet MM combined with DGF and TAC trough levels at 12 months increased the predictive value of dnDSA (AUC 0.735) and AR (AUC 0.730) occurrence. HLA B eplet MM > 9 and TAC trough levels below 5.95 ng/mL at 12 months could increase the risk of early AR occurrence.

CONCLUSIONS

HLA B eplet MM, DGF, and TAC trough levels at 12 months after KT could affect the occurrence of dnDSA and AR in the early stage of KT.

Systematic review of international studies evaluating MDRD and CKD-EPI estimated glomerular filtration rate (eGFR) equations in Black adults

Use of race adjustment in estimating glomerular filtration rate (eGFR) has been challenged given concerns that it may negatively impact the clinical care of Black patients, as it results in Black patients being systematically assigned higher eGFR values than non-Black patients. We conducted a systematic review to assess how well eGFR, with and without race adjustment, estimates measured GFR (mGFR) in Black adults globally. A search across multiple databases for articles published from 1999 to May 2021 that compared eGFR to mGFR and reported outcomes by Black race was performed. We included studies that assessed eGFR using the Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPICr) creatinine equations. Risk of study bias and applicability were assessed with the QUality Assessment of Diagnostic Accuracy Studies-2. Of 13,167 citations identified, 12 met the data synthesis criteria (unique patient cohorts in which eGFR was compared to mGFR with and without race adjustment). The studies included patients with and without kidney disease from Africa (n = 6), the United States (n = 3), Europe (n = 2), and Brazil (n = 1). Of 11 CKD-EPI equation studies, all assessed bias, 8 assessed accuracy, 6 assessed precision, and 5 assessed correlation/concordance. Of 7 MDRD equation studies, all assessed bias, 6 assessed accuracy, 5 assessed precision, and 3 assessed correlation/concordance. The majority of studies found that removal of race adjustment improved bias, accuracy, and precision of eGFR equations for Black adults. Risk of study bias was often unclear, but applicability concerns were low. Our systematic review supports the need for future studies to be conducted in diverse populations to assess the possibility of alternative approaches for estimating GFR. This study additionally provides systematic-level evidence for the American Society of Nephrology-National Kidney Foundation Task Force efforts to pursue other options for GFR estimation.

Removal of the Black race coefficient from the estimated glomerular filtration equation improves transplant eligibility for Black patients at a single center

Race is a social construct that cannot be measured, can be used imprecisely and may contribute to disparities in kidney transplant access for Black patients. At Beth Israel Deaconess Medical Center, we dropped the Black race coefficient in the estimated glomerular filtration rate (eGFR) report in 2017. We conducted a quality improvement project to examine the impact of this change. Before the change, only 26% of our Black patients were listed for preemptive transplant compared to 70% of White patients. Since the change, we found a steady increase in the percentage of Black patients listed before starting dialysis. The average eGFR at listing prior to 2017 was significantly lower in Black patients but after, there was no longer a significant difference. Nine patients "gained" an average of 457 days of wait time directly related to discarding the Black race coefficient. Increased time on the list prior to dialysis initiation allows for evaluation of potential live donors and improves the possibility of a pre-emptive live or deceased donor transplant and allows for a shorter period on dialysis before transplant. In this single center initiative, we demonstrate the benefit of discarding race from the eGFR report for Black patients awaiting kidney transplantation.

Using race to estimate glomerular filtration and its impact in kidney transplantation

Since direct measurement of glomerular filtration rate (GFR) is time-consuming and more expensive, estimated GFR (eGFR) based on measured laboratory values is widely used to determine kidney function. Commonly used formulae to calculate eGFR are dependent on variables, which include filtration markers like serum creatinine and patient characteristics including race. Medical algorithms which utilize race are increasingly being scrutinized, as race is recognized to be a social construct rather than a biologic one. eGFR calculations have important implications for kidney transplantation, both in the listing of candidates as well as in the evaluation of potential kidney donors. This review considers the specific implications of race-based eGFR calculations on recipient evaluation and on decisions related to living kidney donation. We suggest a potential policy solution to ensure that racial and ethnic minority patients are not disadvantaged by eGFR as a result of current calculation methods.

Racial differences in attitudes to clinical pig organ Xenotransplantation

INTRODUCTION

In addition to an organ donor shortage, racial disparities exist at different stages of the transplantation process. Xenotransplantation (XTx) could alleviate these issues. This study describes racial differences in attitudes to XTx among populations who may need a transplant or are transplant recipients.

METHODS

A Likert-scale survey was distributed at outpatient clinics to parents of children with congenital heart disease (CHD) and kidney patients on their attitudes to pig organ XTx. Data from these two groups were stratified by race and compared.

RESULTS

Ninety-seven parents of children with CHD (74.2% White and 25.8% Black) and 148 kidney patients (50% White and 50% Black) responded to our survey. Black kidney patients' acceptance of XTx although high (70%) was lower than White kidney patients (91%; P .003). White kidney patients were more likely to accept XTx if results are similar to allotransplantation (OR 4.14; 95% CI 4.51-11.41), and less likely to be concerned with psychosocial changes when compared to Black kidney patients (receiving a pig organ would change your personality OR 0.08; 95% CI 0.01-0.67 and would change social interaction OR 0.24; 95% CI 0.07-0.78). There were no racial differences in attitudes to XTx among parents of children with CHD.

CONCLUSION

There are differences in attitudes to XTx particularly among Black kidney patients. Because kidneys may be the first organ for clinical trials of XTx, future studies that decrease scientific mistrust and XTx concerns among the Black community are needed to prevent disparities in uptake of possible future organ transplant alternatives.

Immunologic Risk Assessment and Approach to Immunosuppression Regimen in Kidney Transplantation

The outcomes of kidney transplantation show a steady improvement with an increasing number of transplantations and decreasing incidence of acute rejection episodes. Successful transplantation begins with a comprehensive immunologic risk assessment and judicious choice of therapeutic agents. In this review, we discuss the trends in transplant immunosuppression practices and outcomes in the United States. We discuss practical testing algorithms for clinical decision making in induction therapy and fine-tuning maintenance immunosuppression. We introduce assessment tools for immune monitoring after transplantation and speculate on future directions in management.

African-Americans with End Stage Renal Disease in the Early Years of Kidney Transplantation

INTRODUCTION

The first successful kidney transplant in humans was performed in 1954. In the following 25 years, the biomedical, ethical, and social implications of kidney transplantation were widely discussed by both healthcare professionals and the public. Issues relating to race, however, were not commonly addressed, representing a "blind spot" regarding racial disparities in access and health outcomes.

METHODS

Through primary sources in the medical literature and lay press, this paper explores the racial dynamics of kidney transplantation in the 1950-1970s in the United States as the procedure grew from an experimental procedure to the standard of care for patients in end-stage renal disease (ESRD).

RESULTS & DISCUSSION

An extensive search of the medical literature found very few papers about ESRD, dialysis, or renal transplant that mentioned the race of the patients before 1975. While the search did not reveal whether race was explicitly used in determining patient access to dialysis or transplant, the scant data that exist show that African-Americans disproportionately developed ESRD and were underrepresented in these early treatment populations. Transplant outcome data in the United States failed to include race demographics until the late 1970s. The Social Security Act of 1972 (PL 92-603) extended Medicare coverage to almost all Americans with ESRD and led to a rapid increase in both dialysis and kidney transplantation for African-Americans in ESRD, but disparities persist today.

Results of ASERTAA, a Randomized Prospective Crossover Pharmacogenetic Study of Immediate-Release Versus Extended-Release Tacrolimus in African American Kidney Transplant Recipients

BACKGROUND

Differences in tacrolimus dosing across ancestries is partly attributable to polymorphisms in CYP3A5 genes that encode tacrolimus-metabolizing cytochrome P450 3A5 enzymes. The CYP3A5*1 allele, preponderant in African Americans, is associated with rapid metabolism, subtherapeutic concentrations, and higher dose requirements for tacrolimus, all contributing to worse outcomes. Little is known about the relationship between CYP3A5 genotype and the tacrolimus pharmacokinetic area under the curve (AUC) profile in African Americans or whether pharmacogenetic differences exist between conventional twice-daily, rapidly absorbed, immediate-release tacrolimus (IR-Tac) and once-daily extended-release tacrolimus (LifeCycle Pharma Tac [LCPT]) with a delayed absorption profile.

STUDY DESIGN

Randomized prospective crossover study.

SETTING & PARTICIPANTS

50 African American maintenance kidney recipients on stable IR-Tac dosing.

INTERVENTION

Recipients were randomly assigned to continue IR-Tac on days 1 to 7 and then switch to LCPT on day 8 or receive LCPT on days 1 to 7 and then switch to IR-Tac on day 8. The LCPT dose was 85% of the IR-Tac total daily dose.

OUTCOMES

Tacrolimus 24-hour AUC (AUC_0-24), peak and trough concentrations (C_max and C_min), time to peak concentration, and bioavailability of LCPT versus IR-Tac, according to CYP3A5 genotype.

MEASUREMENTS

CYP3A5 genotype, 24-hour tacrolimus pharmacokinetic profiles.

RESULTS

∼80% of participants carried the CYP3A5*1 allele (CYP3A5 expressers). There were no significant differences in AUC_0-24 or C_min between CYP3A5 expressers and nonexpressers during administration of either IR-Tac or LCPT. With IR-Tac, tacrolimus C_max was 33% higher in CYP3A5 expressers compared with nonexpressers (P=0.04): With LCPT, this difference was 11% (P=0.4).

LIMITATIONS

This was primarily a pharmacogenetic study rather than an efficacy study; the follow-up period was too short to capture clinical outcomes.

CONCLUSIONS

Achieving therapeutic tacrolimus trough concentrations with IR-Tac in most African Americans results in significantly higher peak concentrations, potentially magnifying the risk for toxicity and adverse outcomes. This pharmacogenetic effect is attenuated by delayed tacrolimus absorption with LCPT.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov, with study number NCT01962922.