Predicting Tacrolimus Concentrations in the Skin of Adult Kidney Transplant Recipients: A Feasibility Study

Solid organ transplant recipients are at an increased risk of developing skin cancers due to chronic immunosuppression, particularly with calcineurin inhibitors. Tacrolimus is the most prescribed calcineurin inhibitor in this patient cohort, and understanding tacrolimus concentrations in the skin will facilitate the development of anti-cancer preventive and therapeutic strategies. Here, we show that in mice, tacrolimus blood levels peaked rapidly ∼1 h post last oral dose while skin levels rose more slowly and remained high for at least 6 h. Subsequently, tacrolimus skin and blood concentrations were assessed in 15 kidney transplant recipients. The mean age was 61 years, the average time post-transplant was 7 years (range 0-21 years) and 87% were male. The average skin sampling time post tacrolimus dosing was 6 h 32 min. Skin tacrolimus concentrations ranged from 7.1 ng/g to 71.2 ng/g and correlated with blood concentrations (r = 0.6). Mouse and human mean skin concentrations were in a similar range. Our data suggests that tacrolimus measurements in the blood may be used to approximate tacrolimus concentrations in the skin of kidney transplant recipients, and further exploited for the delivery of anti-cancer therapies designed to antagonize the immunosuppressive effects of tacrolimus in the skin.

The association between tacrolimus exposure and tremor, headache and insomnia in adult kidney transplant recipients: A systematic review

PURPOSE

Tremor, headache and insomnia have been linked to the immunosuppressant, tacrolimus. The aim of this systematic review was to determine if there is a correlation between tacrolimus exposure and new-onset tremor, headache and insomnia experienced by adult kidney transplant recipients.

METHODS

PubMed, Embase, Cochrane Library and CINAHL databases were searched up to 11 April 2023 for published studies which reported on tacrolimus exposure in adult kidney transplant recipients, alongside information on treatment-emergent neurologic manifestations, including tremor, headache and insomnia. Review articles, case studies, conference abstracts and articles not published in English in peer-reviewed journals were excluded. The Physiotherapy Evidence Database and Newcastle-Ottawa Quality Assessment Scales were used to assess risk of bias. Extracted data was analysed via a narrative synthesis.

RESULTS

Eighteen studies involving 4030 patients in total were included in the final analysis. These comprised five randomised control trials and thirteen observational studies. Studies failed to find significant association between tacrolimus trough concentrations in whole blood and the incidence of neurologic side effects such as tremor, headache and insomnia; however, in one study the incidence of toxicity requiring a dose reduction increased with increasing, supratherapeutic targeted levels. Females, especially Black females, and older age were positively associated with the prevalence of neurologic adverse effects. Results were conflicting regarding whether extended-release formulations were associated with fewer neurologic complications than immediate-release formulations.

CONCLUSION

The varied study designs and criteria for reporting tremor, headache and insomnia impacted on the quality of the data for exploring the relationship between tacrolimus exposure and the onset of neurologic manifestations experienced after kidney transplantation. Studies that examine defined neurologic complications as the primary outcome, and that consider novel markers of tacrolimus exposure while assessing the potential contribution of multiple covariate factors, are required.

Rejection and graft outcomes in kidney transplant recipients with and without angiotensin II receptor type 1 antibodies

AIM

Angiotensin II type 1 receptor antibody (AT1R Ab) is a non-Human Leucocyte Antigen (HLA) antibody that is maybe associated with early severe kidney transplant rejection and worse graft outcomes. This study aimed to assess the association between AT1R Ab and kidney transplant rejection and graft outcomes.

METHODS

We performed a retrospective analysis of all adult kidney transplant recipients in an Australian centre who had an AT1R Ab test between 1 January 2015 to 30 June 2020. AT1R Ab positive patients were compared to AT1R Ab negative patients. Primary outcomes were rejection risk, type and histopathological severity scores. Secondary outcomes were 8-week graft function and graft loss.

RESULTS

Of 965 kidney transplants that were performed during the study period, 73 patients had AT1R Ab tested; 16 (22%) were positive and 57(78%) were negative. Positive patients were on average younger and had higher level of donor-specific HLA antibodies. Rejection occurred in 13 (81%) positive patients and 41 (72%) negative patients (P = 0.45). No significant differences in rejection type or severity were found. HLA mismatch and peak panel reactive antibody ≥80%, but not AT1R Ab, independently predicted rejection. Average (132 vs. 177 mmol/L, P = 0.302) and graft loss were not significantly different between groups.

CONCLUSION

The study found no evidence that AT1R Ab is associated with rejection type, severity or worse graft function. Future studies should assess its relationship with graft outcomes to help complement immunological risk assessment and potentially provide therapeutic options to alter outcomes.

PREBIOTIC: a study protocol of a randomised controlled trial to assess prebiotic supplementation in kidney transplant recipients for preventing infections and gastrointestinal upset - a feasibility study

BACKGROUND

Modulating the microbiota in the large intestine of kidney transplant recipients through prebiotic supplementation may prevent infectious complications from occurring. To date, there have been no interventional trials which have investigated this novel treatment in kidney transplantation. The aim of PREBIOTIC is to assess the feasibility of performing a randomised controlled trial of prebiotics in reducing infections and gastrointestinal symptoms in kidney transplant recipients.

METHODS

Sixty kidney transplant patients will be recruited to a double-blind, placebo-controlled, randomised feasibility trial. Patients will be provided with prebiotic therapy or placebo for 4 to 6 weeks. Outcomes will include recruitment, adherence, tolerance, retention, laboratory parameters (including serum indoxyl sulphate, ρ-cresyl sulphate and stool collection), patients' self-assessed quality of life, gastrointestinal symptoms and clinical outcomes.

DISCUSSION

This trial will assess the feasibility of prebiotic supplementation in kidney transplant recipients. Prebiotics not only may alter the gut microbiota and their inherent metabolism and production of uraemic toxins but also may prevent infections from occurring in kidney transplant recipients.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry number ACTRN12618001057279p. The date of registration was 25th June 2018, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375370&isReview=true .

High Throughput Omnidirectional Printing of Tubular Microstructures from Elastomeric Polymers

Bioelastomers are extensively used in biomedical applications due to their desirable mechanical strength, tunable properties, and chemical versatility; however, three-dimensional (3D) printing bioelastomers into microscale structures has proven elusive. Herein, a high throughput omnidirectional printing approach via coaxial extrusion is described that fabricates perfusable elastomeric microtubes of unprecedently small inner diameter (350-550 µm) and wall thickness (40-60 µm). The versatility of this approach is shown through the printing of two different polymeric elastomers, followed by photocrosslinking and removal of the fugitive inner phase. Designed experiments are used to tune the microtube dimensions and stiffness to match that of native ex vivo rat vasculature. This approach affords the fabrication of multiple biomimetic shapes resembling cochlea and kidney glomerulus and affords facile, high-throughput generation of perfusable structures that can be seeded with endothelial cells for biomedical applications. Post-printing laser micromachining is performed to generate micro-sized holes (520 µm) in the tube wall to tune microstructure permeability. Importantly, for organ-on-a-chip applications, the described approach takes only 3.6 min to print microtubes (without microholes) over an entire 96-well plate device, in contrast to comparable hole-free structures that take between 1.5 and 6.5 days to fabricate using a manual 3D stamping approach.

Toward Hierarchical Assembly of Aligned Cell Sheets into a Conical Cardiac Ventricle Using Microfabricated Elastomers

Despite current efforts in organ-on-chip engineering to construct miniature cardiac models, they often lack some physiological aspects of the heart, including fiber orientation. This motivates the development of bioartificial left ventricle models that mimic the myofiber orientation of the native ventricle. Herein, an approach relying on microfabricated elastomers that enables hierarchical assembly of 2D aligned cell sheets into a functional conical cardiac ventricle is described. Soft lithography and injection molding techniques are used to fabricate micro-grooves on an elastomeric polymer scaffold with three different orientations ranging from -60° to +60°, each on a separate trapezoidal construct. The width of the micro-grooves is optimized to direct the majority of cells along the groove direction and while periodic breaks are used to promote cell-cell contact. The scaffold is wrapped around a central mandrel to obtain a conical-shaped left ventricle model inspired by the size of a human left ventricle 19 weeks post-gestation. Rectangular micro-scale holes are incorporated to alleviate oxygen diffusional limitations within the 3D scaffold. Cardiomyocytes within the 3D left ventricle constructs showed high viability in all layers after 7 days of cultivation. The hierarchically assembled left ventricle also provided functional readouts such as calcium transients and ejection fraction.

Exploring Transplant Medication-Taking Behaviours in Older Adult Kidney Transplant Recipients: A Qualitative Study of Semi-Structured Interviews

Background

Today, older adult patients routinely undergo kidney transplantation. To support graft survival, patients must take immunosuppressant medicines for the rest of their lives. The post-transplant medication regimen is complex, and barriers to medication taking are likely confounded by both functional and intrinsic changes associated with advancing age. To develop diverse and innovative approaches to support best health outcomes in this vulnerable age group, it is imperative that the degree to which patients’ needs are currently being met, be identified.

Aim

The aim of this study was to examine medication-taking behaviours of kidney transplant recipients transplanted at 60 years of age or older.

Methods

This qualitative study used semi-structured patient interviews to explore how kidney transplant recipients currently manage their immunosuppressant regimen and how they cope after transplantation with the complex routine. Data were themed using the principles of Grounded Theory methodology; with interviews conducted until data saturation was reached.

Results

Quantitative information was collected from 14 participants who ranged in age from 66 to 77 years (at time of interview), and were prescribed a median of 13 (min: 10, max: 26) medicines. The main themes that emerged from the interview were variability in health literacy toward medicines, the importance of support networks, the need to adjust health expectations, factors that were motivators for self-care, different approaches to medication management, and different approaches to medication taking. Overall, it was found that patients prioritised medication taking above all else, and gratitude to their donor was a powerful motivator to adhere. However, strategies to support medication taking were sometimes ineffective when patients’ routine changed.

Conclusions

Future interventions should consider approaches to foster adaptable medication taking behaviours that stand up to changes in the day-to-day routine.

Medication taking is complicated in transplant recipients, due to the number of medicines that need to be taken and the complex nature of the treatment regimen. Challenges in older transplant recipients may be more pronounced and varied compared with younger adults. There are multiple factors that may impact medication taking in older adults and each requires consideration, including level of dependence, living arrangements, level of mobility and manual dexterity, vision and memory, and social situation. To better identify the gaps in support, patients’ current perspectives around medication taking and how they cope after transplantation must be explored. Therefore, this study aimed to identify how older adult transplant recipients currently manage their anti-rejection medicine regimen. Participants described several strategies around how they manage a complex medication regimen. These included cues such as an alarm and linking the time they should take their medication to already established habits such as eating meals. Most participants discussed at length their relationships, and it seems that these relationships are often crucial to post-transplant positivity. Additionally, extreme gratitude to the donor, relative improvement in their life quality (compared with the rapid deterioration in their health when on dialysis), and fear of consequences (particularly graft failure) were important facilitators of self-care and served as timely reminders to prioritise one’s own health. To foster more robust medication-taking habits, future education needs to be tailored to each individual patient and include details about how to link medication taking to already established routines (coined ‘habit stacking’).

Dialysis modality utilization patterns and mortality in older persons initiating dialysis in Australia and New Zealand

AIM

The benefits of dialysis in the older population remain highly debated, particularly for certain dialysis modalities. This study aimed to explore the dialysis modality utilization patterns between in-centre haemodialysis (ICHD), peritoneal dialysis (PD) and home haemodialysis (HHD) and their association with outcomes in older persons.

METHODS

Older persons (≥75 years) initiating dialysis in Australia and New Zealand from 1999 to 2018 reported to the Australia and New Zealand Dialysis and Transplant (ANZDATA) registry were included. The main aim of the study was to characterize dialysis modality utilization patterns and describe individual characteristics of each pattern. Relationships between identified patterns and survival, causes of death and withdrawal were examined as secondary analyses, where the pattern was considered as the exposure.

RESULTS

A total of 10 306 older persons initiated dialysis over the study period. Of these, 6776 (66%) and 1535 (15%) were exclusively treated by ICHD and PD, respectively, while 136 (1%) ever received HHD during their dialysis treatment course. The remainder received both ICHD and PD: 906 (9%) started dialysis on ICHD and 953 (9%) on PD. Different individual characteristics were seen across dialysis modality utilization patterns. Median survival time was 3.0 (95%CI 2.9-3.1) years. Differences in survival were seen across groups and varied depending on the time period following dialysis initiation. Dialysis withdrawal was an important cause of death and varied according to individual characteristics and utilization patterns.

CONCLUSION

This study showed that dialysis modality utilization patterns in older persons are associated with mortality, independent of individual characteristics.

Critically important outcomes for infection in trials in kidney transplantation: An international survey of patients, caregivers and health professionals

BACKGROUND

Infections are a common complication following kidney transplantation, but are reported inconsistently in clinical trials. This study aimed to identify the infection outcomes of highest priority for patients/caregivers and health professionals to inform a core outcome set to be reported in all kidney transplant clinical trials.

METHODS

In an international online survey, participants rated the absolute importance of 16 infections and 8 severity dimensions on 9-point Likert Scales, with 7-9 being critically important. Relative importance was determined using a best-worst scale. Means and proportions of the Likert-scale ratings and best-worst preference scores were calculated.

RESULTS

353 healthcare professionals (19 who identified as both patients/caregiver and healthcare professionals) and 220 patients/caregivers (190 patients, 22 caregivers, 8 who identified as both) from 55 countries completed the survey. Both healthcare professionals and patients/caregivers rated bloodstream (mean 8.4 and 8.5 respectively; aggregate 8.5), kidney/bladder (mean 7.9 and 8.4; aggregate 8.1) and BK virus (mean 8.1 and 8.6; aggregate 8.3) as the top 3 most critically important infection outcomes, whilst infectious death (mean 8.8 and 8.6; aggregate 8.7), impaired graft function (mean 8.4 and 8.7; aggregate 8.5) and admission to the intensive care unit (mean 8.2 and 8.3; aggregate 8.2) were the top 3 severity dimensions. Relative importance (best-worst) scores were consistent.

CONCLUSIONS

Healthcare professionals and patients/caregivers consistently identified bloodstream infection, kidney/bladder infections and BK virus as the three most important infection outcomes, and infectious death, admission to intensive care unit and infection impairing graft function as the three most important infection severity outcomes. This article is protected by copyright. All rights reserved.

Vasculature-on-a-chip platform with innate immunity enables identification of angiopoietin-1 derived peptide as a therapeutic for SARS-CoV-2 induced inflammation

Coronavirus disease 2019 (COVID-19) was primarily identified as a novel disease causing acute respiratory syndrome. However, as the pandemic progressed various cases of secondary organ infection and damage by severe respiratory syndrome coronavirus 2 (SARS-CoV-2) have been reported, including a breakdown of the vascular barrier. As SARS-CoV-2 gains access to blood circulation through the lungs, the virus is first encountered by the layer of endothelial cells and immune cells that participate in host defense. Here, we developed an approach to study SARS-CoV-2 infection using vasculature-on-a-chip. We first modeled the interaction of virus alone with the endothelialized vasculature-on-a-chip, followed by the studies of the interaction of the virus exposed-endothelial cells with peripheral blood mononuclear cells (PBMCs). In an endothelial model grown on a permeable microfluidic bioscaffold under flow conditions, both human coronavirus (HCoV)-NL63 and SARS-CoV-2 presence diminished endothelial barrier function by disrupting VE-cadherin junctions and elevating the level of pro-inflammatory cytokines such as interleukin (IL)-6, IL-8, and angiopoietin-2. Inflammatory cytokine markers were markedly more elevated upon SARS-CoV-2 infection compared to HCoV-NL63 infection. Introduction of PBMCs with monocytes into the vasculature-on-a-chip upon SARS-CoV-2 infection further exacerbated cytokine-induced endothelial dysfunction, demonstrating the compounding effects of inter-cellular crosstalk between endothelial cells and monocytes in facilitating the hyperinflammatory state. Considering the harmful effects of SARS-CoV-2 on endothelial cells, even without active virus proliferation inside the cells, a potential therapeutic approach is critical. We identified angiopoietin-1 derived peptide, QHREDGS, as a potential therapeutic capable of profoundly attenuating the inflammatory state of the cells consistent with the levels in non-infected controls, thereby improving the barrier function and endothelial cell survival against SARS-CoV-2 infection in the presence of PBMC.

Australian human research ethics committee members' confidence in reviewing genomic research applications

Human research ethics committees (HRECs) are evaluating increasing quantities of genomic research applications with complex ethical considerations. Genomic confidence is reportedly low amongst many non-genetics-experts; however, no studies have evaluated genomic confidence levels in HREC members specifically. This study used online surveys to explore genomic confidence levels, predictors of confidence, and genomics resource needs of members from 185 HRECs across Australia. Surveys were fully or partially completed by 145 members. All reported having postgraduate 94 (86%) and/or bachelor 15 (14%) degrees. Participants consisted mainly of researchers (n = 45, 33%) and lay members (n = 41, 30%), affiliated with either public health services (n = 73, 51%) or public universities (n = 31, 22%). Over half had served their HREC [Formula: see text]3 years. Fifty (44%) reviewed genomic studies [Formula: see text]3 times annually. Seventy (60%) had undertaken some form of genomic education. While most (94/103, 91%) had high genomic literacy based on familiarity with genomic terms, average genomic confidence scores (GCS) were moderate (5.7/10, n = 119). Simple linear regression showed that GCS was positively associated with years of HREC service, frequency of reviewing genomic applications, undertaking self-reported genomic education, and familiarity with genomic terms (p < 0.05 for all). Conversely, lay members and/or those relying on others when reviewing genomic studies had lower GCSs (p < 0.05 for both). Most members (n = 83, 76%) agreed further resources would be valuable when reviewing genomic research applications, and online courses and printed materials were preferred. In conclusion, even well-educated HREC members familiar with genomic terms lack genomic confidence, which could be enhanced with additional genomic education and/or resources.

A Survey Study of Trends in Adult Nephrology Advanced Training in Australia and New Zealand

BACKGROUND

There has been considerable growth in nephrology advanced trainee numbers in Australia and New Zealand, with uncertain effects on clinical experience, competence and employment outcomes.

AIM

To review the perceived adequacy and temporal trends of advanced training in nephrology in Australia and New Zealand by evaluating training experiences, personal views on important aspects of training and nephrology, career paths and early employment outcomes.

METHODS

An online survey was distributed to members of the Australian and New Zealand Society of Nephrology via email in December 2020. Responses were sought from current trainees and from nephrologists qualifying since 2014. Likert scale proportions were calculated and group comparisons made using the Chi-square test.

RESULTS

A total of 88 participants returned the survey yielding a response rate of 32%, with a representative sample of trainees and consultants from across Australia and New Zealand. Training was reported as adequate in most aspects of clinical nephrology, although 88% of respondents felt poorly prepared for entering private practice and 61% reported inadequate training in kidney histopathology. Exposure to clinical procedures was variable, with adequate training in percutaneous kidney biopsy but mostly inadequate training in dialysis access insertion. Sixty-nine percent of nephrologists completed their advanced training entirely in large urban centres and 85% worked in an urban area after training. Only 23% of consultants were engaged in full-time clinical employment in their first year post-training and 78% were undertaking at least one of dual specialty training or a higher degree by research. Demand for subspecialty fellowships was high.

CONCLUSION

Trainees and nephrologists in Australia and New Zealand are currently satisfied with their training in most aspects of nephrology, however some clinical experiences are perceived as inadequate and early career paths after advanced training are increasingly diverse. This article is protected by copyright. All rights reserved.

Pharmacokinetic and Pharmacodynamic Considerations in Relation to Calcineurin Usage in Elderly Kidney Transplant Recipients

This review summarizes how possible age-related changes in tacrolimus and cyclosporine pharmacokinetics and pharmacodynamics may influence drug dosing and monitoring in the elderly, and highlights how micro-sampling may be useful in this cohort in the future. Advancing biological age leads to physiological changes that can affect drug absorption, distribution, metabolism and excretion, as well as immune system responsiveness. Some studies have shown that elderly recipients may have higher dose-adjusted exposure and/or lower clearance of the calcineurin inhibitors, suggesting that doses may need to be lowered in elderly recipients. Only one study has examined how aging effects drug target enzyme activity and demonstrated that age does not correlate with the calcineurin inhibitor half-maximal inhibitory concentration. Several studies have shown elderly kidney transplant recipients have increased risk of both morbidity and mortality, compared to younger adults due to increased susceptibility to immunosuppressant side effects, particularly cardiovascular disease, infection and malignancy. Current immunosuppressant dosing and monitoring protocols often make no adjustments for age. Lower maintenance immunosuppressant targets in elderly recipients may decrease patient susceptibility to drug side effects, however, further studies are required and appropriate targets need to be established. Blood draw by micro-sampling may be useful for drug monitoring in this cohort in the future, as blood collection is minimally invasive and less painful than venepuncture. Micro-sampling could also make further pharmacokinetic, pharmacodynamics and outcome studies in the elderly more feasible.

Dialysis initiation in older persons across centres and over time in Australia and New Zealand

AIM

With improved life expectancy over time, the burden of kidney failure resulting in kidney replacement therapy (KRT) in older persons is increasing. This study aimed to describe the age distribution at dialysis initiation in Australia and New Zealand (ANZ) across centres and over time.

METHODS

Adults initiating dialysis as first KRT in ANZ from 1999 to 2018 reported to the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry were included. The primary outcomes were the age distribution and the proportion of older persons (75 years and older) initiating dialysis across centres and over time. Secondary outcomes were characterization of the older population compared with younger people and differences in dialysis modality and treatment trajectories between groups.

RESULTS

Over the study period, 55 382 people initiated dialysis as first KRT, including 10 306 older persons, in 100 centres. Wide variation in age distribution across states/countries was noted, although the proportion of older persons at dialysis initiation did not significantly change over time (from 13% in 1999 to 19% in 2003, then remaining stable thereafter). Older persons were less likely to be treated with home therapies compared with younger people. Older persons were mostly Caucasians; had higher socioeconomic position, more cardiovascular comorbidities and higher eGFR at baseline; and resided in major cities. Higher proportions of older persons per centre were noted in privately funded facilities.

CONCLUSION

Wide variations were noted in the proportions of older persons initiating dialysis across centres and states/country, which were associated with different case-mix across regions, particularly in terms of ethnicity, remoteness and socioeconomic advantage.

Characteristics of the gastrointestinal microbiota in paired live kidney donors and recipients

BACKGROUND

There are few studies that have examined whether dysbiosis occurs in kidney donors and transplant recipients following kidney transplant surgery.

AIM

To ascertain whether changes occur in the gastrointestinal microbiota of the kidney donor and recipient following kidney transplantation.

METHODS

Kidney transplant recipients and their donors were prospectively enrolled in a pilot study to collect one faecal sample prior to, and another faecal sample between four to eight weeks following surgery. Gastrointestinal microbiota richness, Shannon diversity measures and functional assessments of kidney donors and recipients were analysed via metagenomic sequencing.

RESULTS

The study included 12 donors (median age 56 years, 6 females) and 12 recipients (median age 51 years, 3 females). Donor microbiota showed no significant changes in gastrointestinal microbiota richness, Shannon diversity, or functional assessments before and after nephrectomy. Recipient microbiota was altered post-transplant, reflected in reductions of the mean (±SD) richness values (156 ± 46.5 to 116 ± 38.6, p = 0.002), and Shannon diversity (3.57 ± 0.49 to 3.14 ± 0.52, p = 0.007), and a dramatic increase in Roseburia spp. abundance post-transplant (26-fold increase from 0.16 ± 0.0091 to 4.6 ± 0.3; p = 0.006; FDR = 0.12). Functionally, the post-transplant microbial community shifted towards those taxa using the glycolysis pathway (1.2-fold increase; p = 0.02; FDR = 0.26) for energy metabolism, while those functions involved with reactive oxygen species degradation decreased (2.6-fold; p = 0.006; FDR = 0.14).

CONCLUSION

Live donor kidney transplantation and standard care post-transplant result in significant alterations in gut microbiota richness, diversity, composition and functional parameters in kidney transplant recipients but not in their kidney donors.

Rate of decline in residual kidney function pre and post peritoneal dialysis initiation: A post hoc analysis of the IDEAL study

Background

Residual kidney function (RKF) is associated with improved survival and quality of life in dialysis patients. Previous studies have suggested that initiation of peritoneal dialysis (PD) may slow RKF decline compared to the pre-dialysis period. We sought to evaluate the association between PD initiation and RKF decline in the Initiating Dialysis Early And Late (IDEAL) trial.

Methods

In this post hoc analysis of the IDEAL randomized controlled trial, PD participants were included if results from 24-hour urine collections had been recorded within 30 days of dialysis initiation, and at least one value pre- and one value post-dialysis commencement were available. The primary outcome was slope of RKF decline, calculated as mean of urinary creatinine and urea clearances. Secondary outcomes included slope of urine volume decline and time from PD initiation to anuria.

Results

The study included 151 participants (79 early start, 72 late start). The slope of RKF decline was slower after PD initiation (-2.69±0.18mL/min/1.73m²/yr) compared to before PD (-4.09±0.33mL/min/1.73m²/yr; change in slope +1.19 mL/min/1.73m²/yr, 95%CI 0.48–1.90, p<0.001). In contrast, urine volume decline was faster after PD commencement (-0.74±0.05 L/yr) compared to beforehand (-0.57±0.06L/yr; change in slope -0.18L/yr, 95%CI -0.34—-0.01, p = 0.04). No differences were observed between the early- and late-start groups with respect to RKF decline, urine volume decline or time to anuria.

Conclusions

Initiation of PD was associated with a slower decline of RKF compared to the pre-dialysis period.

Variability and trends over time and across centres in haemodialysis weekly duration in Australia and New Zealand

AIM

Haemodialysis treatment prescription varies widely internationally. This study explored patient- and centre-level characteristics associated with weekly haemodialysis hours.

METHODS

Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry data were analysed. Characteristics associated with weekly duration were evaluated using mixed-effects linear regression models with patient- and centre-level covariates as fixed effects, and dialysis centre and state as random effects using the 2017 prevalent in-centre haemodialysis (ICHD) and home haemodialysis (HHD) cohorts. Evaluation of patterns of weekly duration over time analysed the 2000 to 2017 incident ICHD and HHD cohorts.

RESULTS

Overall, 12 494 ICHD and 1493 HHD prevalent patients in 2017 were included. Median weekly treatment duration was 13.5 (interquartile range [IQR] 12-15) hours for ICHD and 16 (IQR 15-20) hours for HHD. Male sex, younger age, higher body mass index, arteriovenous fistula/graft use, Aboriginal and Torres Strait Islander ethnicity and longer dialysis vintage were associated with longer weekly duration for both ICHD and HHD. No centre characteristics were associated with duration. Variability in duration across centres was very limited in ICHD compared with HHD, with variation in HHD being associated with state. Duration did not vary significantly over time for ICHD, whereas longer weekly HHD treatments were reported between 2006 and 2012 compared with before and after this period.

CONCLUSION

This study in the Australian and New Zealand haemodialysis population showed that weekly duration was primarily associated with patient characteristics. No centre effect was demonstrated. Practice patterns seemed to differ across states/countries, with more variability in HHD than ICHD.

Beyond Polydimethylsiloxane: Alternative Materials for Fabrication of Organ-on-a-Chip Devices and Microphysiological Systems

Polydimethylsiloxane (PDMS) is the predominant material used for organ-on-a-chip devices and microphysiological systems (MPSs) due to its ease-of-use, elasticity, optical transparency, and inexpensive microfabrication. However, the absorption of small hydrophobic molecules by PDMS and the limited capacity for high-throughput manufacturing of PDMS-laden devices severely limit the application of these systems in personalized medicine, drug discovery, in vitro pharmacokinetic/pharmacodynamic (PK/PD) modeling, and the investigation of cellular responses to drugs. Consequently, the relatively young field of organ-on-a-chip devices and MPSs is gradually beginning to make the transition to alternative, nonabsorptive materials for these crucial applications. This review examines some of the first steps that have been made in the development of organ-on-a-chip devices and MPSs composed of such alternative materials, including elastomers, hydrogels, thermoplastic polymers, and inorganic materials. It also provides an outlook on where PDMS-alternative devices are trending and the obstacles that must be overcome in the development of versatile devices based on alternative materials to PDMS.

Perioperative antibiotics for preventing post-surgical site infections in solid organ transplant recipients

BACKGROUND

Solid organ transplant recipients are at high risk for infections due to the complexity of surgical procedures combined with the impact of immunosuppression. No consensus exists on the role of antibiotics for surgical site infections in solid organ transplant recipients.

OBJECTIVES

To assess the benefits and harms of prophylactic antimicrobial agents for preventing surgical site infections in solid organ transplant recipients.

SEARCH METHODS

The Cochrane Kidney and Transplant Register of Studies was searched up to 21 April 2020 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs in any language assessing prophylactic antibiotics in preventing surgical site infections in solid organ transplant recipients at any time point after transplantation.

DATA COLLECTION AND ANALYSIS

Two authors independently determined study eligibility, assessed quality, and extracted data. Primary outcomes were surgical site infections and antimicrobial resistance. Other outcomes included urinary tract infections, pneumonias and septicaemia, death (any cause), graft loss, graft rejection, graft function, adverse reactions to antimicrobial agents, and outcomes identified by the Standardised Outcomes of Nephrology Group (SONG), specifically graft health, cardiovascular disease, cancer and life participation. Summary effect estimates were obtained using a random-effects model and results were expressed as risk ratios (RR) and 95% confidence intervals (CI). The quality of the evidence was assessed using the risk of bias and the GRADE approach.

MAIN RESULTS

We identified eight eligible studies (718 randomised participants). Overall, five studies (248 randomised participants) compared antibiotics versus no antibiotics, and three studies (470 randomised participants) compared extended duration versus short duration antibiotics. Risk of bias was assessed as high for performance bias (eight studies), detection bias (eight studies) and attrition bias (two studies). It is uncertain whether antibiotics reduce the incidence of surgical site infections as the certainty of the evidence has been assessed as very low (RR 0.42, 95% CI 0.21 to 0.85; 5 studies, 226 participants; I² = 25%). The certainty of the evidence was very low for all other reported outcomes (death, graft loss, and other infections). It is uncertain whether extended duration antibiotics reduces the incidence of surgical site infections in either solid organ transplant recipients (RR 1.19, 95% CI 0.58 to 2.48; 2 studies, 302 participants; I² = 0%) or kidney-only transplant recipients (RR 0.50, 95% CI 0.05 to 5.48; 1 study, 205 participants) as the certainty of the evidence has been assessed as very low. The certainty of the evidence was very low for all other reported outcomes (death, graft loss, and other infections). None of the eight included studies evaluated antimicrobial agent adverse reactions, graft health, cardiovascular disease, cancer, life participation, biochemical and haematological parameters, intervention cost, hospitalisation length, or overall hospitalisation costs.

AUTHORS' CONCLUSIONS

Due to methodological limitations, risk of bias and significant heterogeneity, the current evidence for the use of prophylactic perioperative antibiotics in transplantation is of very low quality. Further high quality, adequately powered RCTs would help better inform clinical practice.

Patient and center characteristics associated with kidney transplant outcomes: a binational registry analysis

This registry-based study evaluated the contribution of center characteristics to kidney transplant outcomes in adult first kidney transplant recipients in Australia and New Zealand between 2004 and 2014. Primary outcomes were mortality and graft failure, and secondary outcomes were transplant complications. Overall, 6970 transplants from 17 centers were included. For deceased donor transplants, 5-year patient and graft survival rates varied considerably (81.0-93.9% and 72.2-88.3%, respectively). Variations in mortality and graft failure were partially reduced after adjustment for patient characteristics (1% and 20% reductions) and more markedly reduced after adjustment for center characteristics (41% and 55% reductions). For living donor transplants, 5-year patient and graft survival rates varied (89.7-100% and 79.2-96.9%, respectively). Centers with high average total ischemic times (>14 h) were associated with higher mortality for both deceased (adjusted hazard ratio [(AHR] 2.24, 95% CI 1.21-4.13) and living donor transplants (AHR 1.76, 95% CI 1.02-3.04). Small center size (<35 new kidney transplants/year) was associated with a lower hazard of mortality for living donor kidney transplants (AHR 0.48, 95% CI 0.28-0.81). No center characteristic was associated with graft failure. The appreciable variations in deceased donor kidney transplant recipient and graft survival outcomes across centers were attributable to center effects.

Oral versus Intravenous Iron Supplementation in Peritoneal Dialysis Patients

The vast majority of erythropoietin (EPO)–treated peritoneal dialysis (PD) patients require iron supplementation. Most authors and clinical practice guidelines recommend primary oral iron supplementation in PD patients because it is more practical and less expensive. However, numerous studies have clearly demonstrated that oral iron therapy is unable to maintain EPO-treated PD patients in positive iron balance. Once patients become iron-deficient, intravenous iron administration has been found to more effectively augment iron stores and hematologic response than does oral therapy.

We recently performed a prospective, cross-over trial in 28 iron-replete PD patients and showed that twice-monthly outpatient iron polymaltose infusions (200 mg) were a practical and safe alternative to oral iron. That treatment produced significant increases in hemoglobin concentration and body iron stores. The additional expense of intravenous iron therapy was completely offset by reductions in EPO dosage.

Careful monitoring of iron stores is important in patients receiving intravenous iron supplementation in view of epidemiologic links with infection and cardiovascular disease. Nevertheless, a growing body of evidence suggests that, as has been found for hemodialysis patients, intravenous iron therapy is superior to oral iron supplementation in EPO-treated PD patients.

Predictors of Decline of Residual Renal Function in New Peritoneal Dialysis Patients

♦ Objective

The aim of this study was to prospectively evaluate the risk factors for decline of residual renal function (RRF) in an incident peritoneal dialysis (PD) population.

♦ Design

Prospective observational study of an incident PD cohort at a single center.

♦ Setting

Tertiary-care institutional dialysis center.

♦ Participants

The study included 146 consecutive patients commencing PD at the Princess Alexandra Hospital between 1 August 1995 and 1 July 2001 (mean age 54.8 ± 1.4 years, 42% male, 34% diabetic). Patients with failed renal transplants ( n = 26) were excluded.

♦ Main Measurements

Timed urine collections ( n = 642) were performed initially and at 6-month intervals thereafter to measure RRF. The development of anuria was also prospectively recorded.

♦ Results

The mean (±SD) follow-up period was 20.5 ± 14.8 months. The median slope of RRF decline was –0.05 mL/minute/month/1.73 m2. Using binary logistic regression, it was shown that the 50% of patients with more rapid RRF loss (< –0.05 mL/min/month/1.73 m2) were more likely to have had a higher initial RRF at commencement of PD [adjusted odds ratio (AOR) 1.83, 95% confidence interval (CI) 1.39 – 2.40] and a higher baseline dialysate/plasma creatinine ratio at 4 hours (D/P creat; AOR 44.6, 95% CI 1.05 – 1900). On multivariate Cox proportional hazards model analysis, time from commencement of PD to development of anuria was independently predicted by baseline RRF [adjusted hazard ratio (HR) 0.81, 95% CI 0.60 – 0.81], D/P creat (HR 2.87, 95% CI 2.06 – 82.3), body surface area (HR 6.23, 95% CI 1.53 – 25.5), dietary protein intake (HR 2.87, 95% CI 1.06 – 7.78), and diabetes mellitus (HR 1.65, 95% CI 1.00 – 2.72). Decline of RRF was independent of age, gender, dialysis modality, urgency of initiation of dialysis, smoking, vascular disease, blood pressure, medications (including angiotensin-converting enzyme inhibitors), duration of follow-up, and peritonitis rate.

♦ Conclusions

The results of this study suggest that high baseline RRF and high D/P creat ratio are risk factors for rapid loss of RRF. Moreover, a shorter time to the onset of anuria is independently predicted by low baseline RRF, increased body surface area, high dietary protein intake, and diabetes mellitus. Such at-risk patients should be closely monitored for early signs of inadequate dialysis.

Is Obesity a Favorable Prognostic Factor in Peritoneal Dialysis Patients?

Objective

To determine the influence of an elevated body mass index (BMI) on cardiovascular outcomes and survival in peritoneal dialysis (PD) patients.

Design

Prospective, observational study of a prevalent PD cohort at a single center.

Setting

Tertiary care institutional dialysis center.

Patients

The study included all patients with a BMI of at least 20 who had been receiving PD for at least 1 month as of 31 January 1996 ( n = 43). Patients were classified as overweight [BMI > 27.5; mean ± standard error of mean (SEM): 32.1 ± 1.1; n = 14] or normal weight (BMI 20 – 27.5; mean ± SEM: 23.8 ± 0.4; n = 29).

Outcome Measures

Patient survival and adverse cardiovascular events (myocardial infarction, congestive cardiac failure, cerebrovascular accident, and symptomatic peripheral vascular disease) were recorded over a 3-year period.

Results

At baseline, no significant differences were seen between the groups in clinical, biochemical, nutritional, or echocardiographic parameters, except for a lower dietary protein intake (0.97 ± 0.10 g/kg/day vs 1.44 ± 0.10 g/ kg/day, p = 0.004) and a higher proportion of well-nourished patients by subjective global assessment (100% vs 72%, p < 0.05) in the overweight group. After 3 years of follow-up, 29% of overweight patients and 69% of normal-weight patients had died ( p < 0.05). Using a Cox proportional hazards model, a BMI greater than 27.5 was shown to be an independent positive predictor of patient survival, with an adjusted hazard ratio (HR) of 0.09 [95% confidence interval (CI): 0.01 – 0.85; p < 0.05]. However, being overweight did not significantly influence myocardial infarction-free survival (adjusted HR: 0.33; 95% CI: 0.07 – 1.48; p = 0.15) or combined adverse cardiovascular event-free survival (adjusted HR: 0.67; 95% CI: 0.23 – 1.93; p = 0.46).

Conclusions

Obesity conferred a significant survival advantage in our PD population. Obese patients should therefore not be discouraged from receiving PD purely on the basis of BMI. Moreover, maintaining a higher-than-average BMI to preserve “nutritional reserve” may help to reduce the mortality and morbidity rates associated with PD.

Peritoneal Homocysteine Clearance is Inefficient in Peritoneal Dialysis Patients

Objectives

To investigate the degree and the determinants of peritoneal homocysteine (Hcy) clearance and to compare measured Hcy clearance with the Hcy clearance predicted based on molecular weight (MW).

Design

Cross-sectional observational analysis.

Setting

Tertiary care institutional dialysis center.

Patients

Sixty-five stable peritoneal dialysis (PD) patients.

Outcome Measures

Fasting blood and 24-hour pooled dialysate effluents were collected for determination of peritoneal clearances of Hcy (CpHcy), urea (CpUr), and creatinine (CpCr). The dialysate-to-plasma creatinine ratio at 4 hours (D/P Cr 4 h) and levels of red cell folate, B12, ferritin, and C-reactive protein (CRP) were measured concurrently. Observed CpHcy was compared with predicted clearance, based on Hcy plasma protein binding and the relative molecular weights of Hcy, urea, and creatinine.

Results

Plasma concentrations of Hcy averaged 24.6 ± 1.1 μmol/L and were elevated above the upper limit of normal in 59 (91%) patients. The mean dialysate concentration of Hcy was 2.9 ± 0.3 μmol/L, equating to a daily peritoneal elimination of 34.6 ± 3.6 μmol. Observed CpHcy was closely approximated by predicted CpHcy (8.7 ± 0.6 L/week/1.73 m2vs 9.0 ± 0.3 L/week/1.73 m2respectively, p = 0.55). Patients maintained on automated PD ( n = 5) had a CpHcy similar to that of patients treated with continuous ambulatory peritoneal dialysis (8.9 ± 1.0 L/week/1.73 m2vs 8.7 ± 0.6 L/week/1.73 m2, p = 0.92). The CpHcy was significantly correlated with C-reactive protein (CRP), D/P creatinine, CpUr, CpCr, and peritoneal protein loss, but not with plasma Hcy, albumin, B12, ferritin, age, dialysis duration, peritonitis episodes, or daily dialysate effluent volume. By multivariate analysis, the only variables that remained significant independent predictors of CpHcy were CRP and D/P Cr 4 h. High and high-average transporters had a higher CpHcy than low and low-average transporters (9.7 ± 0.8 L/week/1.73 m2vs 7.0 ± 0.7 L/week/1.73 m2, p < 0.05), despite comparably elevated plasma Hcy concentrations [25.2 ± 1.5 μmol/L vs 23.4 ± 1.6 μmol/L, p = nonsignificant (NS)].

Conclusions

Elevated plasma concentrations of Hcy are not efficiently reduced by PD. The relatively low peritoneal clearance of Hcy is largely accounted for by a high degree of plasma protein binding and is significantly influenced by peritoneal membrane permeability.

Transplant associated infections-The role of the gastrointestinal microbiota and potential therapeutic options

Infectious complications are common following kidney transplantation and rank in the top five causes of death in patients with allograft function. Over the last 5 years, there has been emerging evidence that changes in the gastrointestinal microbiota following kidney transplantation may play a key role in the pathogenesis of transplant-associated infections. Different factors have emerged which may disrupt the interaction between the gastrointestinal microbiota and the immune system, which may lead to infective complications in kidney transplant recipients. Over the last 5 years, there has been emerging evidence that changes in the gastrointestinal microbiota following kidney transplantation may play a key role in the pathogenesis of transplant-associated infections. This review will discuss the structure and function of the gastrointestinal microbiota, the changes that occur in the gastrointestinal microbiota following kidney transplantation and the factors underpinning these changes, how these changes may lead to transplant-associated infectious complications and potential treatments which may be instituted to mitigate this risk.

Infectious Complications Following Kidney Transplantation-A Focus on Hepatitis C Infection, Cytomegalovirus Infection and Novel Developments in the Gut Microbiota

The incidence of infectious complications, compared with the general population and the pre-transplant status of the recipient, increases substantially following kidney transplantation, causing significant morbidity and mortality. The potent immunosuppressive therapy given to prevent graft rejection in kidney transplant recipients results in an increased susceptibility to a wide range of opportunistic infections including bacterial, viral and fungal infections. Over the last five years, several advances have occurred that may have changed the burden of infectious complications in kidney transplant recipients. Due to the availability of direct-acting antivirals to manage donor-derived hepatitis C infection, this has opened the way for donors with hepatitis C infection to be considered in the donation process. In addition, there have been the development of medications targeting the growing burden of resistant cytomegalovirus, as well as the discovery of the potentially important role of the gastrointestinal microbiota in the pathogenesis of post-transplant infection. In this narrative review, we will discuss these three advances and their potential implications for clinical practice.

Infection-Related Mortality in Recipients of a Kidney Transplant in Australia and New Zealand

BACKGROUND AND OBJECTIVES

The burden of infectious disease is high among kidney transplant recipients because of concomitant immunosuppression. In this study the incidence of infectious-related mortality and associated factors were evaluated.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this registry-based retrospective, longitudinal cohort study, recipients of a first kidney transplant in Australia and New Zealand between 1997 and 2015 were included. Cumulative incidence of infectious-related mortality was estimated using competing risk regression (using noninfectious mortality as a competing risk event), and compared with age-matched, populated-based data using standardized incidence ratios.

RESULTS

Among 12,519 patients, (median age 46 years, 63% men, 15% diabetic, 6% Indigenous ethnicity), 2197 (18%) died, of whom 416 (19%) died from infection. The incidence of infection-related mortality during the study period (1997-2015) was 45.8 (95% confidence interval [95% CI], 41.6 to 50.4) per 10,000 patient-years. The incidence of infection-related mortality reduced from 53.1 (95% CI, 45.0 to 62.5) per 10,000 person-years in 1997-2000 to 43.9 (95% CI, 32.5 to 59.1) per 10,000 person-years in 2011-2015 (P<0.001) Compared with the age-matched general population, kidney transplant recipients had a markedly higher risk of infectious-related death (standardized incidence ratio, 7.8; 95% CI, 7.1 to 8.6). Infectious mortality was associated with older age (≥60 years adjusted subdistribution hazard ratio [SHR], 4.16; 95% CI, 2.15 to 8.05; reference 20-30 years), female sex (SHR, 1.62; 95% CI, 1.19 to 2.29), Indigenous ethnicity (SHR, 2.87; 95% CI, 1.84 to 4.46; reference white), earlier transplant era (2011-2015: SHR, 0.39; 95% CI, 0.20 to 0.76; reference 1997-2000), and use of T cell-depleting therapy (SHR, 2.43; 95% CI, 1.36 to 4.33). Live donor transplantation was associated with lower risk of infection-related mortality (SHR, 0.53; 95% CI, 0.37 to 0.76).

CONCLUSIONS

Infection-related mortality in kidney transplant recipients is significantly higher than the general population, but has reduced over time. Risk factors include older age, female sex, Indigenous ethnicity, T cell-depleting therapy, and deceased donor transplantation.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2019_08_27_CJN03200319.mp3.

Characterizing the pharmacokinetics and pharmacodynamics of immunosuppressant medicines and patient outcomes in elderly renal transplant patients

This review examines what is currently known about the pharmacokinetics and pharmacodynamics of commonly prescribed immunosuppressant medicines, tacrolimus, cyclosporine, mycophenolate and prednisolone, in elderly renal transplant recipients, and reported patient outcomes in this cohort. Renal transplantation is increasing rapidly in the elderly, however, currently, long-term patient outcomes are relatively poor compared to younger adults. Some studies have suggested that elderly recipients may have higher dose-adjusted exposure and/or lower clearance of the calcineurin inhibitors tacrolimus and cyclosporine; with one study reporting up to 50% reduction in tacrolimus exposure in the elderly. Elderly transplant recipients do not appear to have higher dosage-adjusted exposure to mycophenolic acid (MPA). The effects of ageing on the pharmacokinetics of prednisolone are unknown. Only one study has examined how aging effects drug target enzymes, reporting no difference in baseline inosine 5'-monophosphate dehydrogenase (IMPDH) activity and MPA-induced IMPDH activity in elderly compared to younger adult renal transplant recipients. In elderly transplant recipients, immunosenescence likely lowers the risk of acute rejection, but increases the risk of drug-related adverse effects. Currently, the three main causes of death in elderly renal transplant recipients are cardiovascular disease, infection and malignancy. One study has showed that renal transplant recipients aged over 65 years are seven times more likely to die with a functioning graft compared with young adults (aged 18-29 years). This suggests that an optimal balance between immunosuppressant medicine efficacy and toxicity is not achieved in elderly recipients, and further studies are needed to foster long-term graft and patient survival. Lower maintenance immunosuppressant targets in elderly recipients may decrease patient susceptibility to drug side effects, however, further studies are required and appropriate targets need to be established.

End-Stage Kidney Disease following Surgical Management of Kidney Cancer

BACKGROUND AND OBJECTIVES

We investigated the incidence of ESKD after surgical management of kidney cancer in the Australian state of Queensland, and described patterns in the initiation of kidney replacement therapy resulting from kidney cancer across Australia.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

All newly diagnosed cases of kidney cancer in the Australian state of Queensland between January of 2009 and December of 2014 were ascertained through the Queensland Cancer Registry. There were 2739 patients included in our analysis. Patients who developed ESKD were identified using international classification of disease-10-coded hospital administrative data. Incidence rate and 3-year cumulative incidence were calculated, and multivariable Cox proportional hazards models were used to identify factors associated with ESKD. Additional descriptive analysis was undertaken of Australian population data.

RESULTS

The incidence rate of ESKD in all patients was 4.9 (95% confidence interval [95% CI], 3.9 to 6.2) per 1000 patient-years. The 3-year cumulative incidence was 1.7%, 1.9%, and 1.0% for all patients, and patients managed with radical or partial nephrectomy, respectively. Apart from preoperative kidney disease, exposures associated with increased ESKD risk were age≥65 years (adjusted hazard ratio [aHR], 2.0; 95% CI, 1.2 to 3.2), male sex (aHR, 2.3; 95% CI, 1.3 to 4.3), preoperative diabetes (aHR, 1.8; 95% CI, 1.0 to 3.3), American Society of Anesthesiologists classification ≥3 (aHR, 4.0; 95% CI, 2.2 to 7.4), socioeconomic disadvantage (aHR, 1.6; 95% CI, 0.9 to 2.7), and postoperative length of hospitalization ≥6 days (aHR, 2.1; 95% CI, 1.4 to 3.0). Australia-wide trends indicate that the rate of kidney replacement therapy after oncologic nephrectomy doubled between 1995 and 2015, from 0.3 to 0.6 per 100,000 per year.

CONCLUSIONS

In Queensland between 2009 and 2014, one in 53 patients managed with radical nephrectomy and one in 100 patients managed with partial nephrectomy developed ESKD within 3 years of surgery.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2018_09_28_CJASNPodcast_18_1_.mp3.

Fabricating Degradable Thermoresponsive Hydrogels on Multiple Length Scales via Reactive Extrusion, Microfluidics, Self-assembly, and Electrospinning

While various smart materials have been explored for a variety of biomedical applications (e.g., drug delivery, tissue engineering, bioimaging, etc.), their ultimate clinical use has been hampered by the lack of biologically-relevant degradation observed for most smart materials. This is particularly true for temperature-responsive hydrogels, which are almost uniformly based on polymers that are functionally non-degradable (e.g., poly(N-isopropylacrylamide) (PNIPAM) or poly(oligoethylene glycol methacrylate) (POEGMA)). As such, to effectively translate the potential of thermoresponsive hydrogels to the challenges of remote-controlled or metabolism-regulated drug delivery, cell scaffolds with tunable cell-material interactions, theranostic materials with the potential for both imaging and drug delivery, and other such applications, a method is required to render the hydrogels (if not fully degradable) at least capable of renal clearance following the required lifetime of the material. To that end, this protocol describes the preparation of hydrolytically-degradable hydrazone-crosslinked hydrogels on multiple length scales based on the reaction between hydrazide and aldehyde-functionalized PNIPAM or POEGMA oligomers with molecular weights below the renal filtration limit. Specifically, methods to fabricate degradable thermoresponsive bulk hydrogels (using a double barrel syringe technique), hydrogel particles (on both the microscale through the use of a microfluidics platform facilitating simultaneous mixing and emulsification of the precursor polymers and the nanoscale through the use of a thermally-driven self-assembly and cross-linking method), and hydrogel nanofibers (using a reactive electrospinning strategy) are described. In each case, hydrogels with temperature-responsive properties similar to those achieved via conventional free radical cross-linking processes can be achieved, but the hydrazone cross-linked network can be degraded over time to re-form the oligomeric precursor polymers and enable clearance. As such, we anticipate these methods (which may be generically applied to any synthetic water-soluble polymer, not just smart materials) will enable easier translation of synthetic smart materials to clinical applications.

Mammalian Target of Rapamycin Inhibitors and Clinical Outcomes in Adult Kidney Transplant Recipients

BACKGROUND AND OBJECTIVES

Emerging evidence from recently published observational studies and an individual patient data meta-analysis shows that mammalian target of rapamycin inhibitor use in kidney transplantation is associated with increased mortality. Therefore, all-cause mortality and allograft loss were compared between use and nonuse of mammalian target of rapamycin inhibitors in patients from Australia and New Zealand, where mammalian target of rapamycin inhibitor use has been greater because of heightened skin cancer risk.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Our longitudinal cohort study included 9353 adult patients who underwent 9558 kidney transplants between January 1, 1996 and December 31, 2012 and had allograft survival ≥1 year. Risk factors for all-cause death and all-cause and death-censored allograft loss were analyzed by multivariable Cox regression using mammalian target of rapamycin inhibitor as a time-varying covariate. Additional analyses evaluated mammalian target of rapamycin inhibitor use at fixed time points of baseline and 1 year.

RESULTS

Patients using mammalian target of rapamycin inhibitors were more likely to be white and have a history of pretransplant cancer. Over a median follow-up of 7 years, 1416 (15%) patients died, and 2268 (24%) allografts were lost. There was a higher risk of all-cause mortality with time-varying mammalian target of rapamycin inhibitor use (hazard ratio, 1.47; 95% confidence interval, 1.23 to 1.76) as well as in the fixed time model analyses comparing mammalian target of rapamycin inhibitor use at baseline (hazard ratio, 1.54; 95% confidence interval, 1.22 to 1.93) and 1 year (hazard ratio, 1.63; 95% confidence interval, 1.32 to 2.01). Time-varying mammalian target of rapamycin inhibitor use was associated with higher risk of death because of malignancy (hazard ratio, 1.37; 95% confidence interval, 1.09 to 1.71). There were no statistically significant differences in the risk of all-cause (hazard ratio, 0.98; 95% confidence interval, 0.85 to 1.12) and death-censored (hazard ratio, 0.85; 95% confidence interval, 0.69 to 1.03) allograft loss between the mammalian target of rapamycin inhibitor use and nonuse groups in the time-varying model as well as the fixed time models.

CONCLUSIONS

Mammalian target of rapamycin inhibitor use was associated with a higher risk of all-cause mortality but not allograft loss.

Exploratory study of total and free prednisolone plasma exposure and cushingoid appearance, quality of life and biochemical toxicity in adult male kidney transplant recipients

BACKGROUND AND OBJECTIVE

Long-term adverse effects of oral glucocorticoids are frequent and serious. Large between-patient variability in the pharmacokinetics of prednisolone might explain why drug dose is a poor predictor of drug-related toxicity. The aim of the study was to investigate relationships between prednisolone exposure and adverse effects.

METHODS

Male kidney transplant recipients were recruited for serial blood sampling and assessment of glucocorticoid-related adverse effects including dyslipidaemia, abnormal body fat distribution, Cushingoid appearance and impaired quality of life. Total and free prednisolone plasma concentrations were determined using ultra-high-performance liquid chromatography with tandem mass spectrometric detection. Prednisolone exposure was estimated using a limited sampling strategy.

RESULTS

Fifty-six patients were recruited. Patients had a mean age of 54 years and median time post-transplantation of 75 months. Median prednisolone dose was 5 mg. Mean area under the plasma concentration-time curve was 2390 nmol h/L (±580) (SD) and 175 nmol h/L (±78) for total and free prednisolone, respectively. Waist to upper arm circumference ratio was positively associated with free prednisolone plasma exposure with a Spearman correlation coefficient of 0.30 (p value 0.02). The correlation coefficient was 0.24 (p value 0.08) for neck to upper arm circumference ratio and free prednisolone plasma exposure. The clinical Cushingoid phenotype as determined by the Visual Assessment of Cushing's Severity (VACS) score was associated with a reduced score relating to physical functioning on the SF-12, but there was no significant relationship between free prednisolone plasma exposure and quality-of-life scores. Lipid levels and haemoglobin A1c (HbA1c) were not associated with total or free prednisolone exposure.

CONCLUSIONS

There is a positive correlation between free prednisolone plasma exposure and waist to upper arm circumference ratio in adult male kidney transplant recipients on low maintenance prednisolone doses. There is no significant association between total or free prednisolone plasma exposure and plasma glucose and lipid levels in the low prednisolone dose range.

Controlling the resolution and duration of pulsatile release from injectable magnetic ‘plum-pudding’ nanocomposite hydrogels

Injectable hydrogel nanocomposites with entrapped SPIONs, thermosensitive microgels, and model drugs generate heat when an alternating magnetic field is applied, causing the microgels to deswell and create pore space to promote enhanced drug release.

End-Stage Kidney Disease Due to Fibrillary Glomerulonephritis and Immunotactoid Glomerulopathy - Outcomes in 66 Consecutive ANZDATA Registry Cases

BACKGROUND

Fibrillary glomerulonephritis (FGN) and immunotactoid glomerulopathy (IG) are uncommon and characterised by non-amyloid fibrillary glomerular deposits. The aim of this study was to investigate characteristics and outcomes of patients undergoing renal replacement therapy (RRT) for end-stage kidney disease (ESKD) secondary to FGN and IG.

METHODS

All ESKD patients who commenced RRT in Australia and New Zealand 1 January 1990 to 31 December 2010 were included. Outcomes were assessed by Kaplan-Meier, multivariate logistic-regression analysis and multivariable Cox proportional-hazards survival analysis.

RESULTS

Of 45,216 individuals with ESKD, 55 (0.12%) had FGN and 11 (0.02%) had IG. The median survival of FGN patients on dialysis (5.63 years, 95% CI 3.31-7.96) was not significantly different from patients with other ESKD causes (median 4.01 years, 95% CI 4.34-4.47; log-rank 1.32, p = 0.25), but was significantly longer than that of IG patients (median 2.93 years, 95% CI 0.00-6.17; log-rank 4.8, p = 0.03). Thirteen (24%) FGN patients received 13 renal-allografts, 4 (36%) IG patients received 4 renal-allografts and 11,528 (26%) other ESKD patients received 12,278 renal-allografts. FGN patients experienced comparable outcomes to other ESKD patients for both 10-year patient survival (100 vs. 84%, p = 0.93) and renal-allograft survival (67 vs. 76%, p = 0.06). For IG, the median follow-up was 3.66 years with 75% patient survival and 100% renal-allograft survival. One (8%) FGN patient and 1 (25%) IG patient experienced recurrent FGN and IG respectively in their allograft.

CONCLUSION

Patients with FGN have comparable dialysis and renal transplant outcomes to patients with other causes of ESKD. IG patients have inferior survival on dialysis, although renal transplant outcomes are acceptable. Disease recurrence in renal-allografts was low for both FGN and IG.

Cessation of immunosuppression during chemotherapy for post-transplant lymphoproliferative disorders in renal transplant patients

BACKGROUND

The optimal reduction of immunosuppressive therapy (IST) in renal transplant patients with post-transplant lymphoproliferative disorders (PTLDs) is uncertain. As chemotherapy is immunosuppressive, IST may be stopped during this time without compromising graft function. Subsequent long-term reduction of IST reduces relapse risk, but may increase risk of graft rejection.

METHODS

We performed a retrospective, matched cohort study of adult renal transplant patients in whom IST was ceased during chemotherapy and resumed at lower dose (calcineurin inhibitor at 50%, prednisolone ≤10 mg daily, no third agent) approximately 6 weeks after chemotherapy. Outcomes were compared with those of renal transplant patients without PTLD, matched for creatinine at equivalent time post-transplant that PTLD was diagnosed in cases, as well as for age, gender and year of transplant.

RESULTS

Twenty-four cases of PTLD occurring at a median of 9.2 years post-transplant were compared with 83 matched controls. PTLD cases were followed for a median of 11.9 years. Using competing risks analysis, time to 25% increase in serum creatinine was not significantly different between the two groups [adjusted hazard ratio (HR) 1.8, 95% confidence interval (CI) 0.89-3.6]. Similar results were obtained using multivariable Cox regression analysis (HR 1.19, 95% CI 0.44-3.23). Only one PTLD case experienced a ≥25% increase in creatinine <6 months after IST cessation in the setting of progressive PTLD and death. Three cases recommenced dialysis, compared with three controls (HR 2.5, 95% CI 0.47-13.00). Five-year patient survival rates for cases and controls were 70 and 94%, respectively (P = 0.01).

CONCLUSIONS

IST can be safely ceased during chemotherapy for PTLD in renal transplant patients. Furthermore, long-term reduction in IST is not associated with a significant difference in renal function deterioration. Prospective trials are needed to address the optimal reduction of IST in PTLDs.

Expression of Bcl-xL and Mcl-1 in the nonmelanoma skin cancers of renal transplant recipients

OBJECTIVES

This study aims to investigate how immunosuppression influences the protein expression of antiapoptotic members of the Bcl-2 family-namely, Bcl-xL and Mcl-1-in nonmelanoma skin cancer (NMSC) and the peritumoral epidermis of renal transplant recipients.

METHODS

NMSC and peritumoral epidermis protein expression of Bcl-xL and Mcl-1 were assessed by immunohistochemistry in renal transplant recipients receiving tacrolimus or sirolimus and the general population not receiving immunosuppression.

RESULTS

NMSC from renal transplant recipients compared with patients not receiving immunosuppressant medications had a reduced Bcl-xL expression intensity (P = .042). Mcl-1 expression intensity in NMSC was decreased in tacrolimus-treated patients compared with sirolimus-treated patients and the nonimmunosuppressed population (P = .024). Bcl-xL expression intensity was increased in peritumoral epidermis compared with NMSC (P = .002).

CONCLUSIONS

It was shown for the first time that Bcl-xL and Mcl-1 expression are widespread in the peritumoral epidermis and NMSC of renal transplant recipients. Importantly in NMSC, Bcl-xL expression was reduced with immunosuppression exposure, and Mcl-1 expression was reduced in tacrolimus-treated compared with sirolimus-treated patients.

N-terminal pro-B-type natriuretic peptide variability in stable dialysis patients

BACKGROUND AND OBJECTIVES

Monitoring N-terminal pro-B-type natriuretic peptide (NT-proBNP) may be useful for assessing cardiovascular risk in dialysis patients. However, its biologic variation is unknown, hindering the accurate interpretation of serial concentrations. The aims of this prospective cohort study were to estimate the within- and between-person coefficients of variation of NT-proBNP in stable dialysis patients, and derive the critical difference between measurements needed to exclude biologic and analytic variation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Fifty-five prevalent hemodialysis and peritoneal dialysis patients attending two hospitals were assessed weekly for 5 weeks and then monthly for 4 months between October 2010 and April 2012. Assessments were conducted at the same time in the dialysis cycle and entailed NT-proBNP testing, clinical review, electrocardiography, and bioimpedance spectroscopy. Patients were excluded if they became unstable.

RESULTS

This study analyzed 136 weekly and 113 monthly NT-proBNP measurements from 40 and 41 stable patients, respectively. Results showed that 22% had ischemic heart disease; 9% and 87% had left ventricular systolic and diastolic dysfunction, respectively. Respective between- and within-person coefficients of variation were 153% and 27% for weekly measurements, and 148% and 35% for monthly measurements. Within-person variation was unaffected by dialysis modality, hydration status, inflammation, or cardiac comorbidity. NT-proBNP concentrations measured at weekly intervals needed to increase by at least 46% or decrease by 84% to exclude change due to biologic and analytic variation alone with 90% certainty, whereas monthly measurements needed to increase by at least 119% or decrease by 54%.

CONCLUSIONS

The between-person variation of NT-proBNP was large and markedly greater than within-person variation, indicating that NT-proBNP testing might better be applied in the dialysis population using a relative-change strategy. Serial NT-proBNP concentrations need to double or halve to confidently exclude change due to analytic and biologic variation alone.

Biological variation of high sensitivity cardiac troponin-T in stable dialysis patients: implications for clinical practice

Changes in high sensitivity cardiac troponin-T (hs-cTnT) concentrations may reflect either acute myocardial injury or biological variation. Distinguishing between these entities is essential to accurate diagnosis, however, the biological variation of hs-cTnT in dialysis population is currently unknown. We sought to estimate the within- and between-person coefficients of variation of hs-cTnT in stable dialysis patients, and derive the critical difference between measurements needed to exclude biological variation with 99% confidence.

Fifty-five prevalent haemo- and peritoneal-dialysis patients attending two metropolitan hospitals were assessed on 10 consecutive occasions; weekly for 5 weeks then monthly for 4 months. Assessments were conducted at the same dialysis cycle time-point and entailed hs-cTnT testing, clinical review, electrocardiography, and bioimpedance spectroscopy. Patients were excluded if they developed clinical or physiological instability.

In total 137 weekly and 114 monthly hs-cTnT measurements from 42 stable patients were analysed. Respective between- and within-person coefficients of variation were 83% and 7.9% for weekly measurements, and 79% and 12.6% for monthly measurements. Within-person variation was unaffected by dialysis modality or cardiac co-morbidity. The bidirectional 99% reference change value was –25% and +33% for weekly measurements, and –37% and +58% for monthly measurements.

The between-person variation of hs-cTnT in the dialysis population is markedly greater than within-person variation indicating that hs-cTnT testing is best applied in this population using a relative change strategy. An increase of 33% or a reduction of 25% in serial hs-cTnT concentrations measured at weekly intervals excludes change due to analytical and biological variation alone with 99% confidence.

Comparison of the influence of cyclosporine and tacrolimus on the pharmacokinetics of prednisolone in adult male kidney transplant recipients

BACKGROUND AND OBJECTIVE

Cyclosporine has been observed to precipitate cushingoid features in kidney transplant recipients already on prednisolone. Some pharmacokinetic studies have demonstrated increased prednisolone exposure in patients on cyclosporine therapy compared with azathioprine, whereas other studies have found no difference. The objective of this study was to determine whether cyclosporine impacts on prednisolone exposure as compared with tacrolimus.

METHODS

Adult male kidney transplant recipients treated with prednisolone and either cyclosporine or tacrolimus were recruited for pharmacokinetic blood sampling at the outpatient clinic at the Princess Alexandra Hospital, Brisbane, Australia. Prednisolone plasma concentrations were determined using ultra-high-performance liquid chromatography. Dose-adjusted area under the plasma concentration-time curve (AUC) of free and total prednisolone was estimated using a previously developed limited sampling strategy and non-compartmental analysis.

RESULTS

A total of 55 patients were eligible for analysis; 38 % received cyclosporine and 62 % received tacrolimus co-therapy. No significant difference in mean dose-adjusted total prednisolone AUC from 0 to 6 h post-dose or mean dose-adjusted free prednisolone AUC from 0 to 12 h was observed between the cyclosporine and tacrolimus groups (449 versus 428 nmol·h/L/mg, p = 0.43, and 32 versus 30 nmol·h/L/mg, p = 0.51, respectively).

CONCLUSION

Cyclosporine does not change the dose-adjusted exposure of prednisolone compared with tacrolimus. Adult kidney transplant recipients can therefore continue on their usual prednisolone dose when changing therapy between cyclosporine and tacrolimus.

The outcomes of patients with ESRD and ANCA-associated vasculitis in Australia and New Zealand

BACKGROUND AND OBJECTIVES

This study aimed to evaluate dialysis and transplant outcomes of patients with ESRD secondary to ANCA-associated vasculitis (AAV).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

All ESRD patients who commenced renal replacement therapy in Australia and New Zealand between 1996 and 2010 were included. Outcomes were assessed by Kaplan-Meier, multivariable Cox regression, and competing-risks regression survival analyses.

RESULTS

Of 36,884 ESRD patients, 228 had microscopic polyangiitis (MPA) and 221 had granulomatosis with polyangiitis (GPA). Using competing-risks regression, compared with other causes of ESRD, MPA patients (hazard ratio [HR], 0.89; 95% confidence interval [95% CI], 0.73-1.08; P=0.24) and GPA patients (HR, 0.94; 95% CI, 0.74-1.19; P=0.62) experienced comparable survival on dialysis. Forty-six MPA patients (21%) and 47 GPA (20%) patients received 98 renal allografts. Respective 10-year first graft survival rates in MPA, GPA, and non-AAV patients were 50%, 62%, 70%, whereas patient survival rates were 68%, 85% and 83%, respectively. Compared with non-AAV patients, MPA transplant recipients had higher risks of graft failure (HR, 1.87; 95% CI, 1.07-3.25; P=0.03) and death (HR, 1.94; 95% CI, 1.02-3.69; P=0.04), whereas GPA transplant recipients experienced comparable renal allograft survival (HR, 0.91; 95% CI, 0.43-1.93; P=0.81) and patient survival (HR, 0.58; 95% CI, 0.23-2.27; P=0.58). AAV recurrence was observed in two renal allografts (2%).

CONCLUSIONS

Compared with ESRD patients without AAV, those with GPA have comparable renal replacement therapy outcomes, whereas MPA patients have comparable dialysis survival but poorer renal transplant allograft and patient survival rates.