Evaluating the Impact and Rationale of Race-Specific Estimations of Kidney Function: Estimations from U.S. NHANES, 2015-2018

BACKGROUND

Standard equations for estimating glomerular filtration rate (eGFR) employ race multipliers, systematically inflating eGFR for Black patients. Such inflation is clinically significant because eGFR thresholds of 60, 30, and 20 ml/min/1.73m2 guide kidney disease management. Racialized adjustment of eGFR in Black Americans may thereby affect their clinical care. In this study, we analyze and extrapolate national data to assess potential impacts of the eGFR race adjustment on qualification for kidney disease diagnosis, nephrologist referral, and transplantation listing.

METHODS

Using population-representative cross-sectional data from the United States National Health and Nutrition Examination Survey (NHANES) from 2015-2018, eGFR values for Black Americans were calculated using the Modification of Diet in Renal Disease (MDRD) equation with and without the 1.21 race-specific coefficient using cohort data on age, sex, race, and serum creatinine.

FINDINGS

Without the MDRD eGFR race adjustment, 3.3 million (10.4%) more Black Americans would reach a diagnostic threshold for Stage 3 Chronic Kidney Disease, 300,000 (0.7%) more would qualify for beneficial nephrologist referral, and 31,000 (0.1%) more would become eligible for transplant evaluation and waitlist inclusion.

INTERPRETATION

These findings suggest eGFR race coefficients may contribute to racial differences in the management of kidney. We provide recommendations for addressing this issue at institutional and individual levels.

FUNDING

No external funding was received for this study.

Impact of Low-Dose Fluconazole on Tacrolimus Dosing in Renal Transplant

BACKGROUND

The interaction between azole antifungal therapy and immunosuppressant tacrolimus (TAC) is a barrier to use.

OBJECTIVE

This study quantified the drug interaction between low-dose fluconazole (LDF) and TAC to determine the appropriate TAC dose adjustment when used concurrently in renal transplant recipients.

METHODS

We conducted a single-center retrospective chart review of renal transplant patients >18 years who received LDF or nystatin (NYS), and TAC. The primary outcome was the difference in tacrolimus total daily dose (TAC TDD) for LDF versus NYS groups. Secondary outcomes included days with supratherapeutic, therapeutic and subtherapeutic tacrolimus levels, time to therapeutic level, incidence of adverse drug reactions and graft rejection.

RESULTS

We evaluated 94 patients and included 81. Low-dose fluconazole received a greater TAC TDD prior to post-operative day (POD) 10 (10.5 ± 4.7 mg vs. 7.1 ± 4.5 mg, p < 0.001), but a decreased TAC TDD POD 10 - 30 (8.6 ± 2.2 mg vs. 9.8 ± 0.8 mg, p < 0.001) and following LDF discontinuation (6.9 ± 0.1 mg vs. 9.0 ± 0.4 mg, p < 0.001). Low-dose fluconazole had more patient-days with supratherapeutic (17.9 ± 7.0 vs. 13.9 ± 8.5; p = 0.02) but fewer with subtherapeutic (6.7 ± 5.7 vs. 12.9 ± 7.2; p < 0.01) TAC levels. There was no difference in patient-days with therapeutic TAC levels (15.9 ± 5.8 vs. 14.4 ± 6.6, p = 0.28), meanwhile LDF required less patient-days to therapeutic TAC level (7.1 ± 2.7 vs. 11.5 ± 7.7; p < 0.01). There was no difference in adverse drug reactions between groups and no incidence of graft rejection.

CONCLUSION

A 20% reduction in TAC TDD is warranted in renal transplant patients when used concomitantly with LDF to achieve therapeutic levels.

Identifying a Kidney Transplant Recipient COVID Phenotype to Aid Test Utilization in the Setting of Limited Testing Availability-Does One Exist?

The high morbidity and mortality of COVID-19 in immunocompetent patients raises significant concern for immunosuppressed kidney transplant recipients (KTRs). This level of concern, both on the part of the KTRs and transplant professionals, is heightened by a lack of prior knowledge on how Severe Acute Respiratory Syndrome 2 virus (SARS-CoV-2) may manifest differently in immunosuppressed patients. Characterizing how KTRs may present differently than the general population would allow for more targeted and timely evaluation and treatment of KTRs with COVID-19 infection. METHODS: Without prior knowledge of how this virus would affect our transplant center's delivery of care to KTRs who are SARS-CoV-2 positive or patients under investigation, and in the setting of limited testing availability, we initiated a quality assurance and improvement project (QAPI) to track KTRs followed at our transplant center through the SARS-CoV-2 testing process. RESULTS: Of the 53 symptomatic patients, 20 (38%) tested positive for SARS-CoV-2 either on presentation to the emergency department or referral to a designated outpatient testing center. In addition, 16 (80%) of the 20 patients who tested positive required inpatient treatment. Intriguingly, patients with a history of polyoma BK viremia (BKV) had a higher incidence of testing positive for SARS-CoV-2 compared to patients without a history of BKV (80% and 28%, respectively; P = .002). The Positive Predictive Value and Likelihood ratio was 80% and 6.6 for this association, respectively. Among our KTRs tested, those receiving belatacept had a lower likelihood of testing positive for SARS-CoV-2. This finding approached, but did not achieve, statistical significance (P = .06).

New Organ Allocation System for Combined Liver-Kidney Transplants and the Availability of Kidneys for Transplant to Patients with Stage 4-5 CKD

A new proposal has been created for establishing medical criteria for organ allocation in recipients receiving simultaneous liver-kidney transplants. In this article, we describe the new policy, elaborate on the points of greatest controversy, and offer a perspective on the policy going forward. Although we applaud the fact that simultaneous liver-kidney transplant activity will now be monitored and appreciate the creation of medical criteria for allocation in simultaneous liver-kidney transplants, we argue that some of the criteria proposed, especially those for allocating a kidney to a liver recipient with AKI, are too liberal. We call on the nephrology community to follow the consequences of this new policy and push for a re-examination of the longstanding policy of allocating kidneys to multiorgan transplant recipients before all other candidates. The charge to protect our system of equitable organ allocation is very challenging, but it is a challenge that we must embrace.

Duration of Prophylaxis against Fungal Infection in Kidney Transplant Recipients

Objective—

To compare the efficacy of 2 strategies that use nystatin to prevent thrush and Candida esophagitis in kidney transplant recipients.

Methods—

A retrospective chart review was conducted of adult kidney transplant recipients at our center, where the protocol for prophylaxis against fungal infection was changed in March 2013. Before the protocol change, kidney transplant recipients received nystatin for 1 month (before group) and after the change they received nystatin for the duration of admission (after group). The primary outcome measure was the incidence of thrush and Candida esophagitis within 3 months after transplant. Analyses were conducted on all kidney transplant recipients (intention to treat) and on only those kidney transplant recipients who received at least 1 dose of nystatin (modified intention to treat). Additional data collected included the duration of nystatin and immunosuppression regimens. The Student t test and Fisher exact test were used to calculate P values for continuous and categorical data.

Results—

A total of 84 kidney transplant recipients, 42 in each cohort, were included in the analysis. The groups did not differ significantly at baseline. Nystatin was administered for a mean of 29 days in the before group and 5.74 days in the after group. Overall, 3 kidney transplant recipients (4%), all from the after group, experienced an episode of thrush and no patients experienced Candida esophagitis. Two recipients who experienced thrush did not receive any nystatin.

Conclusions—

Limiting the administration of nystatin to the duration of admission after transplant may be sufficient for prophylaxis of fungal infections in kidney transplant recipients.

Oncologic issues and kidney transplantation: a review of frequency, mortality, and screening

Kidney transplant recipients are at increased risk for development of malignancy compared with the general population, and malignancies occur at an earlier age. This increased risk, as expressed by the standard incidence ratio (SIR), varies widely, but it is highest in malignancies triggered by oncogenic viruses. For other cancers, this increased risk is the direct consequence of immunosuppressants promoting tumor growth and lowering immune system tumor surveillance. In this review, we briefly discuss the common malignancies with increased risk after kidney transplantation, explore the pros and cons associated with screening, and summarize current prevention and treatment recommendations.

A one-day centralized work-up for kidney transplant recipient candidates: a quality improvement report

BACKGROUND

Waiting time for a kidney transplant is calculated from the date the patient is placed on the UNOS (United Network for Organ Sharing) waitlist to the date the patient undergoes transplant. Time from transplant evaluation to listing represents unaccounted waiting time, potentially resulting in longer dialysis exposure for some patients with prolonged evaluation times. There are established disparities demonstrating that groups of patients take longer to be placed on the waitlist and thus have less access to kidney transplant.

STUDY DESIGN

Quality improvement report.

SETTING & PARTICIPANTS

905 patients from a university-based hospital were evaluated for kidney transplant candidacy, and analysis was performed from July 1, 2004, to January 31, 2010.

QUALITY IMPROVEMENT PLAN

A 1-day centralized work-up was implemented on July 1, 2007, whereby the transplant center coordinated the necessary tests needed to fulfill minimal listing criteria.

OUTCOME

Time from evaluation to UNOS listing was compared between the 2 cohorts. Multivariable Cox proportional hazards models were created to assess the relative hazards of waitlist placement comparing 1-day versus conventional work-up and were adjusted for age, sex, race, and education.

RESULTS

Of 905 patients analyzed, 378 underwent conventional evaluation and 527 underwent a 1-day center-coordinated evaluation. Median time to listing in the 1-day center-coordinated evaluation compared with conventional was significantly less (46 vs 226 days, P < 0.001). On multivariable analysis controlling for age, sex, and education level, the 1-day in-center group was 3 times more likely to place patients on the wait list (adjusted HR, 3.08; 95% CI, 2.64-3.59). Listing time was significantly decreased across race, sex, education, and ethnicity.

LIMITATIONS

Single center, retrospective. Variables that may influence transplant practitioners, such as comorbid conditions or functional status, were not assessed.

CONCLUSIONS

A 1-day center-coordinated pretransplant work-up model significantly decreased time to listing for kidney transplant.

Kidney transplantation and HIV: does recipient privacy outweigh the donor's right to information?

BACKGROUND AND OBJECTIVES

There exists an inherent conflict between a kidney donor's right to know key aspects of a recipient's medical history and specific disease, such as HIV, where federal and state statues protect this information. The authors of the live organ donor consensus group expressly stated the principal of a donor's right to recipient information. This information includes the risks and benefits of not only the donation procedure, but also the risks, benefits, and alternative treatment options of the recipient. In this paper, a case will be presented highlighting this conflict and the ethical and legal reasoning used to resolve it.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A 22-year-old woman came forward as a directed kidney donor for an HIV-positive individual. The donor and recipient were medically appropriate for kidney donation and transplantation. During the donor advocacy panel review, there was disagreement regarding whether or not the potential donor had the right to know about the HIV status of the potential recipient.

RESULTS

In living kidney transplantation to HIV-positive individuals, the recipient's right to privacy of information outweighs the donor's right to know.

CONCLUSIONS

Although protecting the recipient's right to privacy is paramount, the donor is still entitled to consider factors a priori that could alter their decision to donate. This can be accomplished by informing the donor that they are not entitled to protected health information of the recipient and that their decision to donate should be based on knowing the recipient is medically appropriate for kidney transplantation.

Plasticin, a type III neuronal intermediate filament protein, assembles as an obligate heteropolymer: implications for axonal flexibility

The assembly characteristics of the neuronal intermediate filament protein plasticin were studied in SW13 cells in the presence and absence of a cytoplasmic filament network. Full-length plasticin cannot polymerize into homopolymers in filament-less SW13c1.2Vim(-) cells but efficiently coassembles with vimentin in SW13c1.1Vim(-) cells. By cotransfecting plasticin and vimentin in SW13c1.1Vim(-) cells, we show that plasticin assembly requires vimentin in noncatalytic amounts. Differing effects on assembly were seen with point mutations of plasticin monomers that were analogous to the keratin mutations that cause epidermolysis bullosa simplex (EBS). In particular, plasticin monomers with point mutations analogous to those in EBS do not uniformly inhibit neurofilament (NF) network formation. A point mutation in the helix termination sequence resulted in complete filament aggregation when coexpressed with vimentin but showed limited coassembly with low- and medium-molecular-weight NF proteins (NF-L and NF-M, respectively). In transfected SW13c1.1Vim(+) cells, a point mutation in the first heptad of the alpha-helical coil region formed equal amounts of filaments, aggregates, and a mixture of filaments and aggregates. Furthermore, coexpression of this point mutation with NF-L and NF-M was associated with a shift toward increased numbers of aggregates. These results suggest that there are important structural differences in assembly properties between homologous fish and mammalian intermediate filament proteins. These structural differences may contribute to the distinctive growth characteristics of the teleost visual pathway.

Cloning of zebrafish vsx1: expression of a paired-like homeobox gene during CNS development

vsx1 is a homeobox gene encoding a paired-type homeodomain and a CVC domain that was originally cloned from an adult goldfish retinal library. We previously reported the spatiotemporal expression pattern of vsx1 in the adult and developing retina of zebrafish and goldfish, and we suggested that vsx1 plays a role in determining the cell fate and maintenance of retinal interneurons. Other related genes encoding a CVC domain, such as vsx2 (alx) and chx10, are expressed both within and outside the retina during development. In this study, we report the cloning of zebrafish vsx1 and its developmental expression in both retinal and nonretinal regions of the CNS in zebrafish embryos. vsx1 expression was detected in a subset of hindbrain and spinal cord neurons before it was expressed in the retina. At about the same time that retinal expression began, the level of vsx1 was decreased in the spinal cord. The expression of vsx1 was progressively restricted, and eventually it was detected only in the inner nuclear layer (INL) of the developing retina. The combined expression patterns of teleost vsx1 and vsx2 (alx) during early zebrafish development encompasses the expression pattern observed for murine Chx10, and indicates a partitioning of function for CVC genes in lower vertebrates.

Gefiltin in zebrafish embryos: sequential gene expression of two neurofilament proteins in retinal ganglion cells

Neurogenesis is correlated with the progressive synthesis of diverse neuronal intermediate filaments (IF) proteins. This apparent developmental regulation of IF protein gene expression suggests that specific neurofilament proteins impart unique structural attributes that support the staged growth of the neuron. In the teleost visual pathway, the sequential expression of two IF genes, plasticin and gefiltin, is linked to the age of retinal ganglion cells (RGCs) and to the regeneration of optic axons after nerve injury. Given this pattern of plasticin and gefiltin expression, we hypothesized that the two proteins would be sequentially expressed in zebrafish retina during development. We analyzed the pattern of gefiltin expression during zebrafish development and compared it to our previous determination of plasticin expression (Canger et al. 1998). Gefiltin is expressed after plasticin, during the later stages of retinal development when axons grow past the optic chiasm and innervate their targets. Thus, during RGC development, expression of plasticin and gefiltin resembles that with optic nerve regeneration. Outside of the visual pathway, gefiltin is predominantly expressed in the central nervous system whereas plasticin is primarily expressed in the peripheral nervous system. These results suggest that the expression of these genes is regulated in a neuron-specific manner. In addition, since plasticin and gefiltin are co-expressed during RGC development, these findings suggest a more complex mechanism of transcriptional regulation which orchestrates the sequential expression of these genes.

Restricted expression of the neuronal intermediate filament protein plasticin during zebrafish development

In the adult goldfish visual pathway, expression of the neuronal intermediate filament (nIF) protein plasticin is restricted to differentiating retinal ganglion cells (RGCs) at the margin of the retina. Following optic nerve injury, plasticin expression is elevated transiently in all RGCs coincident with the early stages of axon regeneration. These results suggest that plasticin may be expressed throughout the nervous system during the early stages of axonogenesis. To test this hypothesis, we analyzed plasticin expression during zebrafish (Danio rerio) neuronal development. By using immunocytochemistry and in situ hybridization, we found that plasticin is expressed in restricted subsets of early zebrafish neurons. Expression coincides with axon outgrowth in projection neurons that pioneer distinct axon tracts in the embryo. Plasticin is expressed first in trigeminal, Rohon-Beard, and posterior lateral line ganglia neurons, which are among the earliest neurons to initiate axonogenesis in zebrafish. Plasticin is expressed also in reticulospinal neurons and in caudal primary motoneurons. Together, these neurons establish the first behavioral responses in the embryo. Plasticin expression also coincides with initial RGC axonogenesis and progressively decreases after RGC axons reach the tectum. At later developmental stages, plasticin is expressed in a subset of the cranial nerves. The majority of plasticin-positive neurons are within or project axons to the peripheral nervous system. Our results suggest that plasticin subserves the changing requirements for plasticity and stability during axonal outgrowth in neurons that project long axons.

Cloning of zebrafish neurofilament cDNAs for plasticin and gefiltin: increased mRNA expression in ganglion cells after optic nerve injury

During retinal growth and optic axon regeneration, the differential expression of the neuronal intermediate filament proteins, plasticin and gefiltin, in the goldfish visual pathway suggests that these proteins support programmed axonal growth. To investigate plasticin and gefiltin during axonogenesis, we turned to the zebrafish, a system that is more amenable to mutational analysis. As a first step, we demonstrated that the intermediate filament compositions of goldfish and zebrafish are similar. In addition, the cDNAs for zebrafish plasticin and gefiltin were cloned and characterized. Using in situ hybridization in retina, we show increased mRNA levels for these proteins following optic nerve crush. Zebrafish plasticin and gefiltin peak and return to baseline levels of expression more rapidly than in goldfish. Furthermore, in the unoperated eye of experimental fish, there was a moderate increase in the levels of plasticin and gefiltin mRNA, suggesting that soluble factors influence the expression of these proteins. The successive expression of plasticin and gefiltin suggests that these neuronal intermediate filament proteins are integral components of axonogenesis. The cloning and characterization of cDNAs for plasticin and gefiltin permit mutational analyses of these proteins during zebrafish axonogenesis.