Predicting the risks of kidney failure and death in adults with moderate to severe chronic kidney disease: multinational, longitudinal, population based, cohort study

OBJECTIVE

To train and test a super learner strategy for risk prediction of kidney failure and mortality in people with incident moderate to severe chronic kidney disease (stage G3b to G4).

DESIGN

Multinational, longitudinal, population based, cohort study.

SETTINGS

Linked population health data from Canada (training and temporal testing), and Denmark and Scotland (geographical testing).

PARTICIPANTS

People with newly recorded chronic kidney disease at stage G3b-G4, estimated glomerular filtration rate (eGFR) 15-44 mL/min/1.73 m2.

MODELLING

The super learner algorithm selected the best performing regression models or machine learning algorithms (learners) based on their ability to predict kidney failure and mortality with minimised cross-validated prediction error (Brier score, the lower the better). Prespecified learners included age, sex, eGFR, albuminuria, with or without diabetes, and cardiovascular disease. The index of prediction accuracy, a measure of calibration and discrimination calculated from the Brier score (the higher the better) was used to compare KDpredict with the benchmark, kidney failure risk equation, which does not account for the competing risk of death, and to evaluate the performance of KDpredict mortality models.

RESULTS

67 942 Canadians, 17 528 Danish, and 7740 Scottish residents with chronic kidney disease at stage G3b to G4 were included (median age 77-80 years; median eGFR 39 mL/min/1.73 m2). Median follow-up times were five to six years in all cohorts. Rates were 0.8-1.1 per 100 person years for kidney failure and 10-12 per 100 person years for death. KDpredict was more accurate than kidney failure risk equation in prediction of kidney failure risk: five year index of prediction accuracy 27.8% (95% confidence interval 25.2% to 30.6%) versus 18.1% (15.7% to 20.4%) in Denmark and 30.5% (27.8% to 33.5%) versus 14.2% (12.0% to 16.5%) in Scotland. Predictions from kidney failure risk equation and KDpredict differed substantially, potentially leading to diverging treatment decisions. An 80-year-old man with an eGFR of 30 mL/min/1.73 m2 and an albumin-to-creatinine ratio of 100 mg/g (11 mg/mmol) would receive a five year kidney failure risk prediction of 10% from kidney failure risk equation (above the current nephrology referral threshold of 5%). The same man would receive five year risk predictions of 2% for kidney failure and 57% for mortality from KDpredict. Individual risk predictions from KDpredict with four or six variables were accurate for both outcomes. The KDpredict models retrained using older data provided accurate predictions when tested in temporally distinct, more recent data.

CONCLUSIONS

KDpredict could be incorporated into electronic medical records or accessed online to accurately predict the risks of kidney failure and death in people with moderate to severe CKD. The KDpredict learning strategy is designed to be adapted to local needs and regularly revised over time to account for changes in the underlying health system and care processes.

Sensing Dying Cells in Health and Disease: The Importance of Kidney Injury Molecule-1

Kidney injury molecule-1 (KIM-1), also known as T-cell Ig and mucin domain-1 (TIM-1), is a widely recognized biomarker for AKI, but its biological function is less appreciated. KIM-1/TIM-1 belongs to the T-cell Ig and mucin domain family of conserved transmembrane proteins, which bear the characteristic six-cysteine Ig-like variable domain. The latter enables binding of KIM-1/TIM-1 to its natural ligand, phosphatidylserine, expressed on the surface of apoptotic cells and necrotic cells. KIM-1/TIM-1 is expressed in a variety of tissues and plays fundamental roles in regulating sterile inflammation and adaptive immune responses. In the kidney, KIM-1 is upregulated on injured renal proximal tubule cells, which transforms them into phagocytes for clearance of dying cells and helps to dampen sterile inflammation. TIM-1, expressed in T cells, B cells, and natural killer T cells, is essential for cell activation and immune regulatory functions in the host. Functional polymorphisms in the gene for KIM-1/TIM-1, HAVCR1 , have been associated with susceptibility to immunoinflammatory conditions and hepatitis A virus-induced liver failure, which is thought to be due to a differential ability of KIM-1/TIM-1 variants to bind phosphatidylserine. This review will summarize the role of KIM-1/TIM-1 in health and disease and its potential clinical applications as a biomarker and therapeutic target in humans.

Self-reported MeasUrement of Physical and PsychosOcial Symptoms Response Tool (SUPPORT-dialysis): systematic symptom assessment and management in patients on in-centre haemodialysis - a parallel arm, non-randomised feasibility pilot study protocol

INTRODUCTION

Patients with kidney failure experience symptoms that are often under-recognised and undermanaged. These symptoms negatively impact health-related quality of life and are associated with adverse clinical outcomes. Regular symptom assessment, using electronic patient reported outcomes measure (ePROMs) linked to systematic symptom management, could improve such outcomes. Clinical implementation of ePROMs have been successful in routine oncology care, but not used for patients on dialysis. In this study, we describe a pilot study of ePROM-based systematic symptom monitoring and management intervention in patients treated with in-centre haemodialysis.

METHODS AND ANALYSIS

This is a parallel-arm, controlled pilot of adult patients receiving in-centre maintenance haemodialysis. Participants in the intervention arm will complete ePROMs once a month for 6 months. ePROMs will be scored real time and the results will be shared with participants and with the clinical team. Moderate-severe symptoms will be flagged using established cut-off scores. Referral options for those symptoms will be shared with the clinical team, and additional symptom management resources will also be provided for both participants and clinicians. Participants in the control arm will be recruited at a different dialysis unit, to prevent contamination. They will receive usual care, except that they will complete ePROMs without the presentation of results to participants of the clinical team. The primary objectives of the pilot are to assess (1) the feasibility of a larger, randomised clinical effectiveness trial and (2) the acceptability of the intervention. Interviews conducted with participants and staff will be assessed using a content analysis approach.

ETHICS AND DISSEMINATION

Ethical approval for this study was obtained from the University Health Network (REB#21-5199) and the William Osler Health System (#23-0005). All study procedures will be conducted in accordance with the standards of University Health Network research ethics board and with the 1964 Helsinki declaration and its later amendments. Results of this study will be shared with participants, patients on dialysis and other stakeholders using lay language summaries, oral presentations to patients and nephrology professionals. We will also be publishing the results in a peer-reviewed journal and at scientific meetings.

PROTOCOL VERSION

4 (16 November 2022).

TRIAL REGISTRATION NUMBER

NCT05515991.

Periconceptional Serum Creatinine and Risk of Childhood Autism Spectrum Disorder: A Research Letter

Background

Autism spectrum disorder (ASD) is a neurodevelopmental condition that manifests in early childhood, in which the maternal metabolic syndrome may be a risk factor. The kidney is a barometer of maternal metabolic syndrome duration and severity.

Objective

The main objective of this study is to determine whether periconceptional kidney function is associated with ASD in early childhood.

Design Setting and Participants

This retrospective population-based cohort study was completed in Ontario, Canada. Included were singleton children born in an Ontario hospital between April 2007 and March 2021, who were alive at age 48 months and whose mother had a recorded prepregnancy body mass index (BMI) and a measured serum creatinine (SCr) between 120 days preconception and 28 days postconception.

Measurement

The main study outcome was a diagnosis of ASD between ages 24 and 48 months.

Methods

Relative risks (RRs) of ASD in association with periconceptional SCr were generated using modified Poisson regression and adjusted for several confounders.

Results

The cohort comprised 86 054 women, who had 89 677 liveborn children surviving to at least 48 months of age. There was no significant association between periconceptional SCr and ASD (RR: 0.86; 95 % confidence interval: [0.67, 1.10]).

Limitations

Selection bias may have arisen had SCr been ordered on clinical grounds.

Conclusions

Further study is warranted to determine whether prepregnancy glomerular hyperfiltration is a marker of ASD and other behavioral conditions in childhood. To do so, a more accurate measure of hyperfiltration is needed than SCr.

The Good and the Bad of SHROOM3 in Kidney Development and Disease: A Narrative Review

Purpose of review

Multiple large-scale genome-wide association meta-analyses studies have reliably identified an association between genetic variants within the SHROOM3 gene and chronic kidney disease. This association extends to alterations in known markers of kidney disease including baseline estimated glomerular filtration rate, urinary albumin-to-creatinine ratio, and blood urea nitrogen. Yet, an understanding of the molecular mechanisms behind the association of SHROOM3 and kidney disease remains poorly communicated. We conducted a narrative review to summarize the current state of literature regarding the genetic and molecular relationships between SHROOM3 and kidney development and disease.

Sources of information

PubMed, PubMed Central, SCOPUS, and Web of Science databases, as well as review of references from relevant studies and independent Google Scholar searches to fill gaps in knowledge.

Methods

A comprehensive narrative review was conducted to explore the molecular mechanisms underlying SHROOM3 and kidney development, function, and disease.

Key findings

SHROOM3 is a unique protein, as it is the only member of the SHROOM group of proteins that regulates actin dynamics through apical constriction and apicobasal cell elongation. It holds a dichotomous role in the kidney, as subtle alterations in SHROOM3 expression and function can be both pathological and protective toward kidney disease. Genome-wide association studies have identified genetic variants near the transcription start site of the SHROOM3 gene associated with chronic kidney disease. SHROOM3 also appears to protect the glomerular structure and function in conditions such as focal segmental glomerulosclerosis. However, little is known about the exact mechanisms by which this protection occurs, which is why SHROOM3 binding partners remain an opportunity for further investigation.

Limitations

Our search was limited to English articles. No structured assessment of study quality was performed, and selection bias of included articles may have occurred. As we discuss future directions and opportunities, this narrative review reflects the academic views of the authors.

Alignment Among Patient, Caregiver, and Health Care Provider Perspectives on Hemodialysis Vascular Access Decision-Making: A Qualitative Study

Background

Updates to the Kidney Disease Outcomes Quality Initiative Clinical Practice Guideline for Vascular Access emphasize the "right access, in the right patient, at the right time, for the right reasons." Although this implies a collaborative approach, little is known about how patients, their caregivers, and health care providers engage in vascular access (VA) decision-making.

Objective

To explore how the perspectives of patients receiving hemodialysis, their caregivers, and hemodialysis care team align and diverge in relation to VA selection.

Design

Qualitative descriptive study.

Setting

Five outpatient hemodialysis centers in Calgary, Alberta.

Participants

Our purposive sample included 19 patients receiving maintenance hemodialysis, 2 caregivers, and 21 health care providers (7 hemodialysis nurses, 6 VA nurses, and 8 nephrologists).

Methods

We conducted semi-structured interviews with consenting participants. Using an inductive thematic analysis approach, we coded transcripts in duplicate and characterized themes addressing our research objective.

Results

While participants across roles shared some perspectives related to VA decision-making, we identified areas where views diverged. Areas of alignment included (1) optimizing patient preparedness-acknowledging decisional readiness and timing, and (2) value placed on trusting relationships with the kidney care team-respecting decisional autonomy with guidance. Perspectives diverged in the following aspects: (1) differing VA priorities and preferences-patients' emphasis on minimizing disruptions to normalcy contrasted with providers' preferences for fistulas and optimizing biomedical parameters of dialysis; (2) influence of personal and peer experience-patients preferred pragmatic, experiential knowledge, whereas providers emphasized informational credibility; and (3) endpoints for VA review-reassessment of VA decisions was prompted by access dissatisfaction for patients and a medical imperative to achieve a functioning access for health care providers.

Limitations

Participation was limited to individuals comfortable communicating in English and from urban, in-center hemodialysis units. Few informal caregivers of people receiving hemodialysis and younger patients participated in this study.

Conclusions

Although patients, caregivers, and healthcare providers share perspectives on important aspects of VA decisions, conflicting priorities and preferences may impact the decisional outcome. Findings highlight opportunities to bridge knowledge and readiness gaps and integrate shared decision-making in the VA selection process.

Dietary potassium liberalization with fruit and vegetables versus potassium restriction in people with chronic kidney disease (DK-Lib CKD): a clinical trial protocol

BACKGROUND

Potassium regulation in the body is primarily done in the kidney. In addition to this, hyperkalemia, occurs in approximately 10% of individuals with chronic kidney disease (CKD) and is associated with elevated all-cause mortality. Individuals with CKD are often told to restrict dietary potassium (K), however, this recommendation is based on low quality evidence. Reduced quality of life, limited dietary choices and nutritional deficiencies are all potential negative outcomes that may occur when restricting dietary K in CKD patients. There is a need for randomized controlled trials investigating the impact of dietary K modification on serum K concentrations in people with CKD.

METHODS

A randomized 2-period crossover design comparing a liberalized K fruit and vegetable diet where participants will be required to consume ~ 3500 mg of dietary K daily, to a standard K restricted diet where participants will be required to consume < 2000 mg of dietary K daily. All participants will begin on a liberalized K run-in period for 2 weeks where they will receive fruit and vegetables home deliveries and for safety will have clinical chemistry, including serum potassium measurements taken after 1 week. Participants will then be randomized into either liberalized K or standard K diet for six weeks and then crossover to the other intervention for another 6 weeks after a 2-week washout period.

DISCUSSION

30 male and female CKD outpatients, ≥ 18 years of age, who have an estimated glomerular filtration rate (eGFR) between 15 and 45 ml/min/1.73m2 and serum K between 4.5 and 5.5 mEq/L. This design would have greater than 80% power to detect a difference of 0.35 mEq/L serum K between groups. Anthropometric measurements, clinical chemistry, dietary recalls, physical function assessments, as well as a quality of life assessments will also be measured in this trial. These findings will provide high quality evidence for, or against, recommendations for dietary K restriction in individuals living with CKD. The removal of K restriction could provide individuals living with CKD more dietary choice leading to improved dietary status and quality of life.

TRIAL REGISTRATION

This trial has received approval from the University of Manitoba Research Ethics board (HS25191 (B2021:104)).

The effect of micro-particle curcumin on chronic kidney disease progression: the MPAC-CKD randomized clinical trial

BACKGROUND

Curcumin is a commonly used herbal supplement with anti-inflammatory and anti-fibrotic properties. Animal studies and small human trials suggest that curcumin reduces albuminuria in patients with chronic kidney disease (CKD). Micro-particle curcumin is a new, more bioavailable formulation of curcumin.

METHODS

To determine whether micro-particle curcumin versus placebo slows the progression of albuminuric CKD we conducted a randomized, double-blind, placebo-controlled trial with 6-month follow-up. We included adults with albuminuria [a random urine albumin-to-creatinine ratio >30 mg/mmol (265 mg/g) or a 24-h urine collection with more than 300 mg of protein] and an estimated glomerular filtration rate (eGFR) between 15 and 60 mL/min/1.73 m2 within the 3 months before randomization. We randomly allocated participants 1:1 to receive micro-particle curcumin capsules (90 mg/day) or matching placebo for 6 months. After randomization, the co-primary outcomes were the changes in albuminuria and the eGFR.

RESULTS

We enrolled 533 participants, but 4/265 participants in the curcumin group and 15/268 in the placebo group withdrew consent or became ineligible. The 6-month change in albuminuria did not differ significantly between the curcumin and placebo groups [geometric mean ratio 0.94, 97.5% confidence interval (CI) 0.82 to 1.08, P = .32]. Similarly, the 6-month change in eGFR did not differ between groups (mean between-group difference -0.22 mL/min/1.73 m2, 97.5% CI -1.38 to 0.95, P = .68).

CONCLUSIONS

Ninety milligrams of micro-particle curcumin daily did not slow the progression of albuminuric CKD over 6 months.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02369549.

Altered expression, but small contribution, of the histone demethylase KDM6A in obstructive uropathy in mice

Epigenetic processes have emerged as important modulators of kidney health and disease. Here, we studied the role of KDM6A (a histone demethylase that escapes X-chromosome inactivation) in kidney tubule epithelial cells. We initially observed an increase in tubule cell Kdm6a mRNA in male mice with unilateral ureteral obstruction (UUO). However, tubule cell knockout of KDM6A had relatively minor consequences, characterized by a small reduction in apoptosis, increase in inflammation and downregulation of the peroxisome proliferator-activated receptor (PPAR) signaling pathway. In proximal tubule lineage HK-2 cells, KDM6A knockdown decreased PPARγ coactivator-1α (PGC-1α) protein levels and mRNA levels of the encoding gene, PPARGC1A. Tubule cell Kdm6a mRNA levels were approximately 2-fold higher in female mice than in male mice, both under sham and UUO conditions. However, kidney fibrosis after UUO was similar in both sexes. The findings demonstrate Kdm6a to be a dynamically regulated gene in the kidney tubule, varying in expression levels by sex and in response to injury. Despite the context-dependent variation in Kdm6a expression, knockout of tubule cell KDM6A has subtle (albeit non-negligible) effects in the adult kidney, at least in males.

Regulatory T-cell dysfunction and its implication for cell therapy

Regulatory T cells (Tregs) are a subtype of CD4+ T cells that can mediate immune tolerance by a multitude of immunomodulatory mechanisms. Treg-based adoptive immunotherapy is currently being tested in multiple phases I and II clinical trials in transplantation and autoimmune diseases. We have learned from the work done on conventional T cells that distinct mechanistic states can define their dysfunctions, such as exhaustion, senescence, and anergy. All three can negatively impact the therapeutic effectiveness of T-cell-based therapies. However, whether Tregs are susceptible to such dysfunctional states is not well studied, and results are sometimes found to be controversial. In addition, Treg instability and loss of FOXP3 expression is another Treg-specific dysfunction that can decreasein their suppressive potential. A better understanding of Treg biology and pathological states will be needed to compare and interpret the results of the different clinical and preclinical trials. We will review herein Tregs' mechanisms of action, describe different T-cell dysfunction subtypes and how and if they apply to Tregs (exhaustion, senescence, anergy, and instability), and finally how this knowledge should be taken into consideration when designing and interpreting Treg adoptive immunotherapy trials.

Screening for Primary Aldosteronism Among Hypertensive Adults with Obstructive Sleep Apnea: A Retrospective Population-Based Study

BACKGROUND

Hypertension plus obstructive sleep apnea (OSA) is recommended in some guidelines as an indication to screen for primary aldosteronism (PA), yet prior data has brought the validity of this recommendation into question. Given this context, it remains unknown whether this screening recommendation is being implemented into clinical practice.

METHODS

We conducted a population-based retrospective cohort study of all adult Ontario (Canada) residents with hypertension plus OSA from 2009 to 2020 with follow-up through 2021 utilizing provincial health administrative data. We measured the proportion of individuals who underwent PA screening via the aldosterone-to-renin ratio by year. We further examined screening rates among patients with hypertension plus OSA by the presence of concurrent hypokalemia and resistant hypertension. Clinical predictors associated with screening were assessed via Cox regression modeling.

RESULTS

The study cohort included 53,130 adults with both hypertension and OSA, of which only 634 (1.2%) underwent PA screening. Among patients with hypertension, OSA, and hypokalemia, the proportion of eligible patients screened increased to 2.8%. Among patients ≥65 years with hypertension, OSA, and prescription of ≥4 antihypertensive medications, the proportion of eligible patients screened was 1.8%. Older age was associated with a decreased likelihood of screening while hypokalemia and subspecialty care with internal medicine, cardiology, endocrinology, or nephrology were associated with an increased likelihood of screening. No associations with screening were identified with sex, rural residence, cardiovascular disease, diabetes, or respirology subspecialty care.

CONCLUSIONS

The population-level uptake of the guideline recommendation to screen all patients with hypertension plus OSA for PA is exceedingly low.

Minimal Kidney Disease Phenotype in Shroom3 Heterozygous Null Mice

Background

Shroom family member 3 (SHROOM3) encodes an actin-associated protein that regulates epithelial morphology during development. Several genome-wide association studies (GWAS) have identified genetic variances primarily in the 5' region of SHROOM3, associated with chronic kidney disease (CKD) and poor transplant outcomes. These genetic variants are associated with alterations in Shroom3 expression.

Objective

Characterize the phenotypic abnormalities associated with reduced Shroom3 expression in postnatal day 3-, 1-month and 3-month-old mice.

Methods

The Shroom3 protein expression pattern was determined by immunofluorescence. We generated Shroom3 heterozygous null mice (Shroom3Gt/+) and performed comparative analyses with wild type littermates based on somatic and kidney growth, gross renal anatomy, renal histology, renal function at postnatal day 3, 1 month, and 3 months.

Results

The Shroom3 protein expression localized to the apical regions of medullary and cortical tubular epithelium in postnatal wild type kidneys. Co-immunofluorescence studies confirmed protein expression localized to the apical side of the tubular epithelium in proximal convoluted tubules, distal convoluted tubules, and collecting ducts. While Shroom3 heterozygous null mice exhibited reduced Shroom3 protein expression, no differences in somatic and kidney growth were observed when compared to wild type mice. Although, rare cases of unilateral hypoplasia of the right kidney were observed at postnatal 1 month in Shroom3 heterozygotes. Yet renal histological analysis did not reveal any overt abnormalities in overall kidney structure or in glomerular and tubular organization in Shroom3 heterozygous null mice when compared to wild type mice. Analysis of the apical-basolateral orientation of the tubule epithelium demonstrated alterations in the proximal convoluted tubules and modest disorganization in the distal convoluted tubules at 3 months in Shroom3 heterozygotes. Additionally, these modest abnormalities were not accompanied by tubular injury or physiological defects in renal and cardiovascular function.

Conclusion

Taken together, our results describe a mild kidney disease phenotype in adult Shroom3 heterozygous null mice, suggesting that Shroom3 expression and function may be required for proper structure and maintenance of the various tubular epithelial parenchyma of the kidney.

CENtral blood pressure Targeting: a pragmatic RAndomized triaL in advanced Chronic Kidney Disease (CENTRAL-CKD): A Clinical Research Protocol

Background

Emerging data favor central blood pressure (BP) over brachial cuff BP to predict cardiovascular and kidney events, as central BP more closely relates to the true aortic BP. Considering that patients with advanced chronic kidney disease (CKD) are at high cardiovascular risk and can have unreliable brachial cuff BP measurements (due to high arterial stiffness), this population could benefit the most from hypertension management using central BP measurements.

Objective

To assess the feasibility and efficacy of targeting central BP as opposed to brachial BP in patients with CKD G4-5.

Design

Pragmatic multicentre double-blinded randomized controlled pilot trial.

Setting

Seven large academic advanced kidney care clinics across Canada.

Patients

A total of 116 adults with CKD G4-5 (estimated glomerular filtration rate [eGFR] < 30 mL/min) and brachial cuff systolic BP between 120 and 160 mm Hg. The key exclusion criteria are 1) ≥ 5 BP drugs, 2) recent acute kidney injury, myocardial infarction, stroke, heart failure or injurious fall, 3) previous kidney replacement therapy.

Methods

Double-blind randomization to a central or a brachial cuff systolic BP target (both < 130 mm Hg) as measured by a validated central BP device. The study duration is 12 months with follow-up visits every 2 to 4 months, based on local practice. All other aspects of CKD management are at the discretion of the attending nephrologist.

Outcomes

Primary Feasibility: Feasibility of a large-scale trial based on predefined components. Primary Efficacy: Carotid-femoral pulse wave velocity at 12 months. Others: Efficacy (eGFR decline, albuminuria, BP drugs, and quality of life); Events (major adverse cardiovascular events, CKD progression, hospitalization, mortality); Safety (low BP events and acute kidney injury).

Limitations

May be challenging to distinguish whether central BP is truly different from brachial BP to the point of significantly influencing treatment decisions. Therapeutic inertia may be a barrier to successfully completing a randomized trial in a population of CKD G4-5. These 2 aspects will be evaluated in the feasibility assessment of the trial.

Conclusion

This is the first trial to evaluate the feasibility and efficacy of using central BP to manage hypertension in advanced CKD, paving the way to a future large-scale trial.

Trial registration

clinicaltrials.gov (NCT05163158).

Two-step screening for depressive symptoms in patients treated with kidney replacement therapies: a cross-sectional analysis

BACKGROUND

Systematic screening for depressive symptoms may identify patients who may benefit from clinical assessment and psychosocial support. Here we assess a two-step screening using ultrabrief pre-screeners [Edmonton Symptom Assessment Survey-revised Depression item (ESASr-D) or Patient Health Questionnaire-2 (PHQ-2)] followed by the Patient-Reported Outcomes Measurement Information System Depression questionnaire (PROMIS-D) to identify depressive symptoms in patients on kidney replacement therapies.

METHODS

We conducted a cross-sectional study of adults (kidney transplant recipients or treated with dialysis) in Toronto, ON, Canada. We simulated various two-step screening scenarios where only patients above a pre-screening cut-off score on the ESASr-D or PHQ-2 would move to step 2 (PROMIS-D). Screening performance was evaluated by sensitivity, specificity and positive and negative predictive values using the Patient Health Questionnaire-9 (PHQ-9) as the referent. The average number of items completed by patients in different scenarios was reported.

RESULTS

Of 480 participants, 60% were male with a mean age of 55 years. Based on PHQ-9, 19% of patients had moderate or severe depressive symptoms. Pre-screening with a PHQ-2 score ≥1 combined with a PROMIS-D score of ≥53 provided the best two-step results (sensitivity 0.81, specificity 0.84, NPV 0.95). Two-step screening also reduces question burden.

CONCLUSIONS

A two-step screening using a PHQ-2 score ≥1 followed by a PROMIS-D score ≥53 has good sensitivity and specificity for identifying potentially significant depressive symptoms among patients on kidney replacement therapies. This approach has lower question burden. Screened-in patients will need further clinical assessment to establish a diagnosis.

Investigation of N,N,N-Trimethyl-L-alanyl-L-proline Betaine (TMAP) as a Biomarker of Kidney Function

Glomerular filtration rate (GFR) is the most widely used tool for the measurement of kidney function, but endogenous biomarkers such as cystatin C and creatinine have limitations. A previous metabolomic study revealed N,N,N-trimethyl-L-alanyl-L-proline betaine (TMAP) to be reflective of kidney function. In this study, we developed a quantitative LCMS assay for the measurement of TMAP and evaluated TMAP as a biomarker of GFR. An assay to measure TMAP was developed using liquid chromatography-mass spectrometry. After validation of the method, we applied it to plasma samples from three distinct kidney disease patient cohorts: nondialysis chronic kidney disease (CKD) patients, patients receiving peritoneal and hemodialysis, and living kidney donors. We investigated whether TMAP was conserved in other mammalian and nonmammalian species, by analyzing plasma samples from Wistar rats with diet-induced CKD and searching for putative matches to the m/z for TMAP and its known fragments in the raw sample data repository "Metabolomics Workbench". The assay can measure plasma TMAP at a lower limit of quantitation (100 ng/mL) with an interday precision and accuracy of 12.8 and 12.1%, respectively. In all three patient cohorts, TMAP concentrations are significantly higher in patients with CKD than in controls with a normal GFR. Further, TMAP concentrations are also elevated in rats with CKD and TMAP is present in the sap produced from Acer saccharum trees. TMAP concentration is inversely related to GFR suggesting that it is a marker of kidney function. TMAP is present in nonmammalian species suggesting that it is part of a biologically conserved process.

A Health Survey-Based Prediction Equation for Incident CKD

BACKGROUND

Prediction tools that incorporate self-reported health information could increase CKD awareness, identify modifiable lifestyle risk factors, and prevent disease. We developed and validated a survey-based prediction equation to identify individuals at risk for incident CKD (eGFR <60 ml/min per 1.73 m2), with and without a baseline eGFR.

METHODS

A cohort of adults with an eGFR ≥70 ml/min per 1.73 m2 from Ontario, Canada, who completed a comprehensive general population health survey between 2000 and 2015 were included (n=22,200). Prediction equations included demographics (age, sex), comorbidities, lifestyle factors, diet, and mood. Models with and without baseline eGFR were derived and externally validated in the UK Biobank (n=15,522). New-onset CKD (eGFR <60 ml/min per 1.73 m2) with ≤8 years of follow-up was the primary outcome.

RESULTS

Among Ontario individuals (mean age, 55 years; 58% women; baseline eGFR, 95 (SD 15) ml/min per 1.73 m2), new-onset CKD occurred in 1981 (9%) during a median follow-up time of 4.2 years. The final models included lifestyle factors (smoking, alcohol, physical activity) and comorbid illnesses (diabetes, hypertension, cancer). The model was discriminating in individuals with and without a baseline eGFR measure (5-year c-statistic with baseline eGFR: 83.5, 95% confidence interval [CI], 82.2 to 84.9; without: 81.0, 95% CI, 79.8 to 82.4) and well calibrated. In external validation, the 5-year c-statistic was 78.1 (95% CI, 74.2 to 82.0) and 66.0 (95% CI, 61.6 to 70.4), with and without baseline eGFR, respectively, and maintained calibration.

CONCLUSIONS

Self-reported lifestyle and health behavior information from health surveys may aid in predicting incident CKD.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast.aspx?p=CJASN&e=2023_01_10_CJN05650522.mp3.

Primary Aldosteronism: State-of-the-Art Review

We are witnessing a revolution in our understanding of primary aldosteronism (PA). In the past 2 decades, we have learned that PA is a highly prevalent syndrome that is largely attributable to pathogenic somatic mutations, that contributes to cardiovascular, metabolic, and kidney disease, and that when recognized, can be adequately treated with widely available mineralocorticoid receptor antagonists and/or surgical adrenalectomy. Unfortunately, PA is rarely diagnosed, or adequately treated, mainly because of a lack of awareness and education. Most clinicians still possess an outdated understanding of PA; from primary care physicians to hypertension specialists, there is an urgent need to redefine and reintroduce PA to clinicians with a modern and practical approach. In this state-of-the-art review, we provide readers with the most updated knowledge on the pathogenesis, prevalence, diagnosis, and treatment of PA. In particular, we underscore the public health importance of promptly recognizing and treating PA and provide pragmatic solutions to modify clinical practices to achieve this.

A Novel Mouse Model of Idiopathic Nephrotic Syndrome Induced by Immunization with the Podocyte Protein Crb2

BACKGROUND

The cause of podocyte injury in idiopathic nephrotic syndrome (INS) remains unknown. Although recent evidence points to the role of B cells and autoimmunity, the lack of animal models mediated by autoimmunity limits further research. We aimed to establish a mouse model mimicking human INS by immunizing mice with Crb2, a transmembrane protein expressed at the podocyte foot process.

METHODS

C3H/HeN mice were immunized with the recombinant extracellular domain of mouse Crb2. Serum anti-Crb2 antibody, urine protein-to-creatinine ratio, and kidney histology were studied. For signaling studies, a Crb2-expressing mouse podocyte line was incubated with anti-Crb2 antibody.

RESULTS

Serum anti-Crb2 autoantibodies and significant proteinuria were detected 4 weeks after the first immunization. The proteinuria reached nephrotic range at 9-13 weeks and persisted up to 29 weeks. Initial kidney histology resembled minimal change disease in humans, and immunofluorescence staining showed delicate punctate IgG staining in the glomerulus, which colocalized with Crb2 at the podocyte foot process. A subset of mice developed features resembling FSGS after 18 weeks. In glomeruli of immunized mice and in Crb2-expressing podocytes incubated with anti-Crb2 antibody, phosphorylation of ezrin, which connects Crb2 to the cytoskeleton, increased, accompanied by altered Crb2 localization and actin distribution.

CONCLUSION

The results highlight the causative role of anti-Crb2 autoantibody in podocyte injury in mice. Crb2 immunization could be a useful model to study the immunologic pathogenesis of human INS, and may support the role of autoimmunity against podocyte proteins in INS.

Association of Clonal Hematopoiesis of Indeterminate Potential with Worse Kidney Function and Anemia in Two Cohorts of Patients with Advanced Chronic Kidney Disease

BACKGROUND

Clonal hematopoiesis of indeterminate potential (CHIP) is an inflammatory premalignant disorder resulting from acquired genetic mutations in hematopoietic stem cells. This condition is common in aging populations and associated with cardiovascular morbidity and overall mortality, but its role in CKD is unknown.

METHODS

We performed targeted sequencing to detect CHIP mutations in two independent cohorts of 87 and 85 adults with an eGFR<60 ml/min per 1.73m2. We also assessed kidney function, hematologic, and mineral bone disease parameters cross-sectionally at baseline, and collected creatinine measurements over the following 5-year period.

RESULTS

At baseline, CHIP was detected in 18 of 87 (21%) and 25 of 85 (29%) cohort participants. Participants with CHIP were at higher risk of kidney failure, as predicted by the Kidney Failure Risk Equation (KFRE), compared with those without CHIP. Individuals with CHIP manifested a 2.2-fold increased risk of a 50% decline in eGFR or ESKD over 5 years of follow-up (hazard ratio 2.2; 95% confidence interval, 1.2 to 3.8) in a Cox proportional hazard model adjusted for age, sex, and baseline eGFR. The addition of CHIP to 2-year and 5-year calibrated KFRE risk models improved ESKD predictions. Those with CHIP also had lower hemoglobin, higher ferritin, and higher red blood cell mean corpuscular volume versus those without CHIP.

CONCLUSIONS

In this exploratory analysis of individuals with preexisting CKD, CHIP was associated with higher baseline KFRE scores, greater progression of CKD, and anemia. Further research is needed to define the nature of the relationship between CHIP and kidney disease progression.

Meta-GWAS Reveals Novel Genetic Variants Associated with Urinary Excretion of Uromodulin

BACKGROUND

Uromodulin, the most abundant protein excreted in normal urine, plays major roles in kidney physiology and disease. The mechanisms regulating the urinary excretion of uromodulin remain essentially unknown.

METHODS

We conducted a meta-analysis of genome-wide association studies for raw (uUMOD) and indexed to creatinine (uUCR) urinary levels of uromodulin in 29,315 individuals of European ancestry from 13 cohorts. We tested the distribution of candidate genes in kidney segments and investigated the effects of keratin-40 (KRT40) on uromodulin processing.

RESULTS

Two genome-wide significant signals were identified for uUMOD: a novel locus (P 1.24E-08) over the KRT40 gene coding for KRT40, a type 1 keratin expressed in the kidney, and the UMOD-PDILT locus (P 2.17E-88), with two independent sets of single nucleotide polymorphisms spread over UMOD and PDILT. Two genome-wide significant signals for uUCR were identified at the UMOD-PDILT locus and at the novel WDR72 locus previously associated with kidney function. The effect sizes for rs8067385, the index single nucleotide polymorphism in the KRT40 locus, were similar for both uUMOD and uUCR. KRT40 colocalized with uromodulin and modulating its expression in thick ascending limb (TAL) cells affected uromodulin processing and excretion.

CONCLUSIONS

Common variants in KRT40, WDR72, UMOD, and PDILT associate with the levels of uromodulin in urine. The expression of KRT40 affects uromodulin processing in TAL cells. These results, although limited by lack of replication, provide insights into the biology of uromodulin, the role of keratins in the kidney, and the influence of the UMOD-PDILT locus on kidney function.

Dipeptidase-1 governs renal inflammation during ischemia reperfusion injury

The mechanisms that drive leukocyte recruitment to the kidney are incompletely understood. Dipeptidase-1 (DPEP1) is a major neutrophil adhesion receptor highly expressed on proximal tubular cells and peritubular capillaries of the kidney. Renal ischemia reperfusion injury (IRI) induces robust neutrophil and monocyte recruitment and causes acute kidney injury (AKI). Renal inflammation and the AKI phenotype were attenuated in Dpep1^-/- mice or mice pretreated with DPEP1 antagonists, including the LSALT peptide, a nonenzymatic DPEP1 inhibitor. DPEP1 deficiency or inhibition primarily blocked neutrophil adhesion to peritubular capillaries and reduced inflammatory monocyte recruitment to the kidney after IRI. CD44 but not ICAM-1 blockade also decreased neutrophil recruitment to the kidney during IRI and was additive to DPEP1 effects. DPEP1, CD44, and ICAM-1 all contributed to the recruitment of monocyte/macrophages to the kidney following IRI. These results identify DPEP1 as a major leukocyte adhesion receptor in the kidney and potential therapeutic target for AKI.

Increased Excess Pressure After Creation of an Arteriovenous Fistula in End-Stage Renal Disease

BACKGROUND

Reservoir-wave analysis (RWA) separates the arterial waveform into reservoir and excess pressure (XSP) components, where XSP is analogous to flow and related to left ventricular workload. RWA provides more detailed information about the arterial tree than traditional blood pressure (BP) parameters. In end-stage renal disease (ESRD), we have previously shown that XSP is associated with increased mortality and is higher in patients with arteriovenous fistula (AVF). In this study, we examined whether XSP increases after creation of an AVF in ESRD.

METHODS

Before and after a mean of 3.9 ± 1.2 months following creation of AVF, carotid pressure waves were recorded using arterial tonometry. XSP and its integral (XSPI) were derived using RWA through pressure wave analysis alone. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (CF-PWV).

RESURLTS

In 38 patients (63% male, age 59 ± 15 years), after AVF creation, brachial diastolic BP decreased (79 ± 10 vs. 72 ± 12 mm Hg, P = 0.002), but the reduction in systolic BP, was not statistically significant (133 ± 20 vs. 127 ± 26 mm Hg, P = 0.137). However, carotid XSP (14 [12-19] to 17 [12-22] mm Hg, P = 0.031) and XSPI increased significantly (275 [212-335] to 334 [241-439] kPa∙s, P = 0.015), despite a reduction in CF-PWV (13 ± 3.6 vs. 12 ± 3.5 m/s, P = 0.025).

CONCLUSIONS

Creation of an AVF resulted in increased XSP in this population, despite improvement in diastolic BP and aortic stiffness. These findings underline the complex hemodynamic impact of AVF on the cardiovascular system.

The Impact of Protein Type on Phosphorus Intake, Serum Phosphate Concentrations, and Nutrition Status in Adults with Chronic Kidney Disease: A Critical Review

Lower phosphorus intake to prevent hyperphosphatemia for those with chronic kidney disease (CKD) is often recommended. Plant proteins are frequently restricted for their high phosphorus content despite having lower bioavailability. To summarize the evidence on protein type and dietary phosphorus intake, serum phosphate concentrations, and nutritional adequacy in adults with CKD, a search in MEDLINE via Ovid was conducted. Citation lists were reviewed to identify any additional articles. Sixteen articles were included-7 intervention (n = 290) and 9 observational (n = 4933). All intervention trials reported high-plant-protein diets provided adequate protein and adhered to low phosphorus diet guidelines. All intervention trials reported higher plant-protein intake was associated with lower serum phosphate; however, only 2 achieved statistical significance. For observational studies, 2 reported that higher proportions of plant to animal protein resulted in lower phosphorus intake but equivalent serum phosphate concentrations. Two reported that plant protein and animal protein had equivalent correlation values to phosphorus intake and no correlation to serum phosphate concentrations. One trial reported lower total phosphorus and protein intake among those who consumed more plant proteins but did not examine serum concentrations. Four reported lower serum phosphate concentrations among those who consumed more plant proteins but did not report dietary phosphorus intake. Of the observational studies that reported on protein intake, all reported lower protein intake among those with higher versus lower plant-protein intake. BMI tended to be lower among those consuming more plant protein. There was not a consistent relation between protein type and albumin concentrations. Routine restriction of plant-protein foods to prevent hyperphosphatemia in CKD would likely benefit from re-evaluation, as evidence does not suggest that higher plant-protein intake leads to higher serum phosphate concentrations or worse nutritional status, although longer-duration intervention trials with larger sample sizes appear to be warranted.

Opportunities To Improve Diabetes Care in the Hemodialysis Unit: A Cohort Study in Ontario, Canada

Background

Patients with diabetes receiving chronic, in-center hemodialysis face healthcare challenges. We examined the prevalence of gaps in their diabetes care, explored regional differences, and determined predictors of care gaps.

Methods

We conducted a population-based, retrospective study between January 1, 2016 and January 1, 2018 in Ontario, Canada. We included adults with prevalent diabetes mellitus receiving in-center hemodialysis as of January 1, 2018 and examined the proportion with (1) insufficient or excessive glycemic monitoring, (2) suboptimal screening for diabetes-related complications (retinopathy and cardiovascular screening), (3) hospital encounters for hypo- or hyperglycemia, and (4) hospital encounters for hypertension in the 2 years prior (January 1, 2016 to January 1, 2018). We then identified patient, provider, and health-system factors associated with more than one care gap and used multivariable logistic regression to determine predictors. Further, we used geographic information systems to explore spatial variation in gaps.

Results

There were 4173 patients with diabetes receiving in-center hemodialysis; the mean age was 67 years, 39% were women, and the majority were of lower socioeconomic status. Approximately 42% of patients had more than one diabetes care gap, the most common being suboptimal retinopathy screening (53%). Significant predictors of more than one gap included younger age, female sex, shorter duration of diabetes, dementia, fewer specialist visits, and not seeing a physician for diabetes. There was evidence of spatial variation in care gaps across our region.

Conclusions

There are opportunities to improve diabetes care in patients receiving in-center hemodialysis, particularly screening for retinopathy. Focused efforts to bring diabetes support to high-risk individuals might improve their care and outcomes.

Recombinant apoptosis inhibitor of macrophage protein reduces delayed graft function in a murine model of kidney transplantation

Reperfusion injury following cold and warm ischemia (IRI) is unavoidable during kidney transplantation and contributes to delayed graft function (DGF) and premature graft loss. Death of tubular epithelial cells (TECs) by necrosis during IRI releases pro-inflammatory mediators (e.g. HMGB1), propagating further inflammation (necroinflammation) and tissue damage. Kidney Injury Molecule-1 (KIM-1) is a phagocytic receptor upregulated on proximal TECs during acute kidney injury. We have previously shown that renal KIM-1 protects the graft against transplant associated IRI by enabling TECs to clear apoptotic and necrotic cells, and that recognition of necrotic cells by KIM-1 is augmented in the presence of the opsonin, apoptosis inhibitor of macrophages (AIM). Here, we tested whether recombinant AIM (rAIM) could be used to mitigate transplant associated IRI. We administered rAIM or vehicle control to nephrectomised B6 mice transplanted with a single B6 donor kidney. Compared to grafts in vehicle-treated recipients, grafts from rAIM-treated mice exhibited significantly less renal dysfunction, tubular cell death, tissue damage, tubular obstruction, as well as local and systemic inflammation. Both mouse and human rAIM enhanced the clearance of necrotic cells by murine and human TECs, respectively in vitro. These data support testing of rAIM as a potential therapeutic agent to reduce DGF following kidney transplantation.

miR299a-5p promotes renal fibrosis by suppressing the antifibrotic actions of follistatin

Caveolin-1 (cav-1), an integral protein of the membrane microdomains caveolae, is required for synthesis of matrix proteins by glomerular mesangial cells (MC). Previously, we demonstrated that the antifibrotic protein follistatin (FST) is transcriptionally upregulated in cav-1 knockout MC and that its administration is protective against renal fibrosis. Here, we screened cav-1 wild-type and knockout MC for FST-targeting microRNAs in order to identity novel antifibrotic therapeutic targets. We identified that miR299a-5p was significantly suppressed in cav-1 knockout MC, and this was associated with stabilization of the FST 3'UTR. Overexpression and inhibition studies confirmed the role of miR299a-5p in regulating FST expression. Furthermore, the profibrotic cytokine TGFβ1 was found to stimulate the expression of miR299a-5p and, in turn, downregulate FST. Through inhibition of FST, miR299a-5p overexpression augmented, while miR299a-5p inhibition diminished TGFβ1 profibrotic responses, whereas miR299a-5p overexpression re-enabled cav-1 knockout MC to respond to TGFβ1. In vivo, miR299a-5p was upregulated in the kidneys of mice with chronic kidney disease (CKD). miR299a-5p inhibition protected these mice against renal fibrosis and CKD severity. Our data demonstrate that miR299a-5p is an important post-transcriptional regulator of FST, with its upregulation an important pathogenic contributor to renal fibrosis. Thus, miR299a-5p inhibition offers a potential novel therapeutic approach for CKD.

Characteristics and Effectiveness of Dedicated Care Programs for Patients Starting Dialysis: A Systematic Review

BACKGROUND

Dedicated care programs that provide increased support to patients starting dialysis are increasingly being used to reduce the risk of complications. The objectives of this systematic review were to determine the characteristics of existing programs and their effect on patient outcomes.

METHODS

We searched Embase, MEDLINE, Web of Science, Cochrane CENTRAL, and CINAHL from database inception to November 20, 2019 for English-language studies that evaluated dedicated care programs for adults starting maintenance dialysis in the inpatient or outpatient setting. Any study design was eligible, but we required the presence of a control group and prespecified patient outcomes. We extracted data describing the nature of the interventions, their components, and the reported benefits.

RESULTS

The literature search yielded 12,681 studies. We evaluated 66 full texts and included 11 studies (n=6812 intervention patients); eight of the studies evaluated hemodialysis programs. All studies were observational, and there were no randomized controlled trials. The most common interventions included patient education (n=11) and case management (n=5), with nurses involved in nine programs. The most common outcomes were mortality (n=8) and vascular access (n=4), with only three studies reporting on the uptake of home dialysis and none on transplantation. We identified four high-quality studies that combined patient education and case management; in these programs, the relative reduction in 90-day mortality ranged from 22% (95% CI, -3% to 41%) to 49% (95% CI, 33% to 61%). Pooled analysis was not possible due to study heterogeneity.

CONCLUSIONS

Few studies have evaluated dedicated care programs for patients starting dialysis, especially their effect on home dialysis and transplantation. Whereas multidisciplinary care models that combine patient education with case management appear to be promising, additional prospective studies that involve patients in their design and execution are needed before widespread implementation of these resource-intensive programs.

Strategies for incorporating patient-reported outcomes in the care of people with chronic kidney disease (PRO kidney): a protocol for a realist synthesis

BACKGROUND

Patient-reported outcomes and experience measures (jointly referred to here as PROs) are internationally recognized as a means for patients to provide information about their quality of life, symptoms, and experiences with care. Although increasingly recognized as key to improving the quality of healthcare at individual (e.g., patients, caregivers, and providers) and aggregate (e.g., government, policy/system-wide decision-making) levels, there are important knowledge gaps in our understanding of how PROs are, and can be, used across different settings, particularly in nephrology to enhance person-centered care. This knowledge is needed for developing strategies to guide optimal use of PROs in nephrology care. Currently, no strategies exist. The purpose of this review is to address this knowledge gap by answering the following realist question: How can PROs be used to enhance person-centered nephrology care, both at individual and aggregate levels?

METHODOLOGY

Realist synthesis is an explanatory approach to data synthesis that aims to explain how context and mechanisms influence the outcome of an intervention. An initial program theory will be developed through the systematic search of the published literature in bibliographic databases (Ovid MEDLINE, Ovid Embase, EBSCOhost CINAHL, Web of Science, and Scopus) on existing theories explaining how PROs are used in healthcare settings. This initial program theory will then be tested and refined through the process of realist synthesis, using context-mechanism-outcome configurations. A kidney-specific program theory will then be created to address the utilization of PROs in nephrology across individual and aggregate levels to augment person-centered care. Searching will be iterative and refined as data is extracted and analyzed using a pilot-tested context + mechanism = outcome heuristic. Throughout, we will consult methodological experts, research team practitioners, and the Patient Advisory Committee to help refine the theories. Last, we will develop and disseminate knowledge translation products widely to knowledge user groups.

DISCUSSION

The utilization of PROs remains a challenge in nephrology. The findings from this synthesis will provide a framework to guide both policy makers and practitioners on how to enhance person-centered care through successful utilization of PROs across individual and aggregate levels in nephrology.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017056063.

Heterogeneous Nuclear Ribonucleoprotein F Stimulates Sirtuin-1 Gene Expression and Attenuates Nephropathy Progression in Diabetic Mice

We investigated the mechanism of heterogeneous nuclear ribonucleoprotein F (hnRNP F) renoprotective action in a type 2 diabetes (T2D) mouse model (db/db). Immortalized rat renal proximal tubular cells (IRPTCs) and kidneys from humans with T2D were also studied. The db/db mice developed hyperglycemia, oxidative stress, and nephropathy at age 20 weeks compared with their db/m littermates. These abnormalities, with the exception of hyperglycemia, were attenuated in db/dbhnRNP F-transgenic (Tg) mice specifically overexpressing hnRNP F in their RPTCs. Sirtuin-1, Foxo3α, and catalase expression were significantly decreased in RPTCs from db/db mice and normalized in db/dbhnRNP F-Tg mice. In vitro, hnRNP F overexpression stimulated Sirtuin-1 and Foxo3α with downregulation of acetylated p53 expression and prevented downregulation of Sirtuin-1 and Foxo3α expression in IRPTCs by high glucose plus palmitate. Transfection of Sirtuin-1 small interfering RNA prevented hnRNP F stimulation of Foxo3α and downregulation of acetylated p53 expression. hnRNP F stimulated Sirtuin-1 transcription via hnRNP F-responsive element in the Sirtuin-1 promoter. Human T2D kidneys exhibited more RPTC apoptosis and lower expression of hnRNP F, SIRTUIN-1, and FOXO3α than nondiabetic kidneys. Our results demonstrate that hnRNP F protects kidneys against oxidative stress and nephropathy via stimulation of Sirtuin-1 expression and signaling in diabetes.

ACCESS HD pilot: A randomised feasibility trial Comparing Catheters with fistulas in Elderly patientS Starting haemodialysis

INTRODUCTION

The selection of the type of vascular access for haemodialysis is an important intervention question. However, only observational studies are available to inform decision-making in this area, and they are at high risk of selection bias. While a clinical trial comparing the effects of the 2 most frequently chosen strategies for haemodialysis access (fistulas and catheters) on patient important and 'hard' clinical end points is needed, the feasibility of such a trial is uncertain.

METHODS AND ANALYSIS

This open-label pilot randomised controlled trial will test the feasibility and safety of randomising elderly people (≥65 years) who start haemodialysis with a central venous catheter (the most common initial type of haemodialysis access), and are eligible to receive a fistula, to a catheter-based strategy (comparator) or to a fistula-based strategy (intervention). We will enrol 100 patients at 10 centres across Canada. Participants assigned to the catheter-strategy arm will continue to use catheters; participants assigned to the fistula-strategy arm will receive a surgical attempt at fistula creation. The inclusion criteria are designed to minimise the risk of protocol violation and attrition. The primary outcome is feasibility, which we will assess by measuring: (1) the proportion of participants deemed eligible for the trial who consent to randomisation; and (2) the proportion of participants randomised to the intervention who receive the fistula surgery within 90 days of randomisation. Secondary outcomes will include safety outcomes, the reasons people and healthcare providers may not accept randomisation, and the reasons sites may not adhere to the trial protocol.

ETHICS AND DISSEMINATION

The Conjoint Health Research Ethics Board at the University of Calgary approved the study protocol. We will submit the results of this feasibility study in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT02675569, Pre-results.