Major Outcomes With Personalized Dialysate TEMPerature (MyTEMP): Rationale and Design of a Pragmatic, Registry-Based, Cluster Randomized Controlled Trial

Navigating the consent river: questions to consider before waiving consent requirements in pragmatic cluster randomised trials

The robust design and conduct of pragmatic cluster randomised trials may be in tension with the ethical requirement to obtain written informed consent from prospective research participants. In our experience, researchers tend to focus on whether a waiver of consent is appropriate for their studies. However, pragmatic cluster randomised trials raise other important questions that have direct implications for determining when an alteration or waiver of consent is permissible. To assist those involved in the design, conduct and review of pragmatic cluster randomised trials, we outline four critical questions to consider: (1) What is the nature of the intervention being evaluated? (2) Is the choice to use cluster randomisation justified? (3) Can the risk of recruitment bias be addressed? and (4) Is an alteration or waiver of consent appropriately justified? We recommend that researchers and research ethics committees conduct a stepwise analysis of a planned cluster randomised trial using these questions. To illustrate the application of this stepwise analysis, we use three pragmatic cluster randomised trials in the haemodialysis setting as case studies.

Centre-level fluid management practices in the BISTRO trial and their lack of association with participant fluid status and blood pressure in non-anuric haemodialysis patients

INTRODUCTION

Fluid assessment and management is a key aspect of good dialysis care and is affected by patient-level characteristics and potentially centre-level practices. In this secondary analysis of the BISTRO trial we wished to establish whether centre-level practices with the potential to affect fluid status were stable over the course of the trial and explore if they had any residual associations with participant's fluid status.

METHODS

Two surveys (S) of fluid management practices were conducted in 32 participating centres during the trial, (S1: 2017-18 and S2: 2021-22). Domains interrogated included: dialysate sodium concentration, (D-[Na+]), fluid and salt intake, residual kidney function, use of diuretics, incremental start, approaches to fluid assessment, management and dialysate temperature, (D-oC). Associations of these practices with the closeness of the participant's post-dialysis target weight to their normally hydrated weight, pre- and post-dialysis systolic (SBP) and diastolic blood pressure, (DBP), were analysed using intra-class correlations and multilevel modelling with adjustment for visit, age, sex and comorbidity burden.

RESULTS

Variations in centre practices were reported but did not change during the trial, apart from some relaxation in salt and fluid restriction in S2. For our measures of fluid status, measured 2501 times in 439 non-anuric incident haemodialysis patients, centre-level intraclass correlations were extremely low, whereas patient-level correlations ranged between 0.12 and 0.47, strongest for pre- and post-dialysis-SBP, less so for post-dialysis-DBP. Multi-level analysis found no associations between D-[Na+], or assessment methods of fluid status. In S2, one centre, routinely using a D-Co of 35°C had more divergence between the target and normally hydrated weight, but this was not observed in S1, and no other associations were found.

CONCLUSIONS

Centre-level fluid management practices were stable over the course of the BISTRO trial, and in contrast to patient-level factors, no centre-level associations were detected with fluid status or blood pressure. This may be because the trial imposed a standardised approach to fluid assessment in all trial participants who at least initially had residual kidney function, potentially over-riding the effects of other centre practices. Survey responses revealed substantial scope for developing and evaluating standardised protocols to optimise fluid management.

Use cases of registry-based randomized controlled trials-A review of the registries' contributions and constraints

Registry-based randomized controlled trials (RRCTs) can combine the advantages of registries with those of randomization. This review aimed to expand the current knowledge on RRCT utilization and implementation by providing a comprehensive overview of RRCT use cases. A targeted literature search was conducted through July 2023 to identify articles on RRCTs. Information regarding the RRCT characteristics, their utilization, and the registries' contributions and the constraints faced was extracted. Descriptive statistics were used. We identified 102 RRCTs in 110 publications. RRCTs were mostly performed for the assessment of medical devices or surgical/clinical procedures (n = 45), followed by drugs (n = 30). More than half of the RRCTs were conducted in the Nordic countries (n = 58) and the most used registry types were health service registries/administrative health data (n = 63), followed by disease registries (n = 46). Approximately half of the RRCTs (n = 53) utilized additional data sources aside from registry data. The contribution of a registry to the RRCT was mostly for data collection and study follow-up (n = 90-92), followed by patient recruitment (n = 56-61), and randomization (n = 28-38), with varying levels of transparency in reporting. We collated author-reported constraints related to the used registries into four overarching themes, that is, data availability and completeness, data quality, representativeness, and registry infrastructure and accessibility. This review shows that RRCTs are already used in different domains and geographic regions. Guidelines on structured and transparent reporting of RRCT methods and the optimal use are, however, needed to inform decision-making by health authorities and to reach their full potential.

The Ottawa Statement implementation guidance document for cluster randomized trials in the hemodialysis setting

Research teams are increasingly interested in using cluster randomized trial (CRT) designs to generate practice-guiding evidence for in-center maintenance hemodialysis. However, CRTs raise complex ethical issues. The Ottawa Statement on the Ethical Design and Conduct of Cluster Randomized Trials, published in 2012, provides 15 recommendations to address ethical issues arising within 7 domains: justifying the CRT design, research ethics committee review, identifying research participants, obtaining informed consent, gatekeepers, assessing benefits and harms, and protecting vulnerable participants. But applying the Ottawa Statement recommendations to CRTs in the hemodialysis setting is complicated by the unique features of the setting and population. Here, with the help of content experts and patient partners, we co-developed this implementation guidance document to provide research teams, research ethics committees, and other stakeholders with detailed guidance on how to apply the Ottawa Statement recommendations to CRTs in the hemodialysis setting, the result of a 4-year research project. Thus, our work demonstrates how the voices of patients, caregivers, and all stakeholders may be included in the development of research ethics guidance.

Update on Hemodialysis-Induced Multiorgan Ischemia: Brains and Beyond

Hemodialysis is a life-saving treatment for patients with kidney failure. However, patients requiring hemodialysis have a 10-20 times higher risk of cardiovascular morbidity and mortality than that of the general population. Patients encounter complications such as episodic intradialytic hypotension, abnormal perfusion to critical organs (heart, brain, liver, and kidney), and damage to vulnerable vascular beds. Recurrent conventional hemodialysis exposes patients to multiple episodes of circulatory stress, exacerbating and being aggravated by microvascular endothelial dysfunction. This promulgates progressive injury that leads to irreversible multiorgan injury and the well-documented higher incidence of cardiovascular disease and premature death. This review aims to examine the underlying pathophysiology of hemodialysis-related vascular injury and consider a range of therapeutic approaches to improving outcomes set within this evolved rubric.‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬.

Hyperhydration to Improve Kidney Outcomes in Children with Shiga Toxin-Producing E. coli Infection: a multinational embedded cluster crossover randomized trial (the HIKO STEC trial)

BACKGROUND

Shiga toxin-producing E. coli (STEC) infections affect children and adults worldwide, and treatment remain solely supportive. Up to 15-20% of children infected by high-risk STEC (i.e., E. coli that produce Shiga toxin 2) develop hemolytic anemia, thrombocytopenia, and kidney failure (i.e., hemolytic uremic syndrome (HUS)), over half of whom require acute dialysis and 3% die. Although no therapy is widely accepted as being able to prevent the development of HUS and its complications, several observational studies suggest that intravascular volume expansion (hyperhydration) may prevent end organ damage. A randomized trial is needed to confirm or refute this hypothesis.

METHODS

We will conduct a pragmatic, embedded, cluster-randomized, crossover trial in 26 pediatric institutions to determine if hyperhydration, compared to conservative fluid management, improves outcomes in 1040 children with high-risk STEC infections. The primary outcome is major adverse kidney events within 30 days (MAKE30), a composite measure that includes death, initiation of new renal replacement therapy, or persistent kidney dysfunction. Secondary outcomes include life-threatening, extrarenal complications, and development of HUS. Pathway eligible children will be treated per institutional allocation to each pathway. In the hyperhydration pathway, all eligible children are hospitalized and administered 200% maintenance balanced crystalloid fluids up to targets of 10% weight gain and 20% reduction in hematocrit. Sites in the conservative fluid management pathway manage children as in- or outpatients, based on clinician preference, with the pathway focused on close laboratory monitoring, and maintenance of euvolemia. Based on historical data, we estimate that 10% of children in our conservative fluid management pathway will experience the primary outcome. With 26 clusters enrolling a mean of 40 patients each with an intraclass correlation coefficient of 0.11, we will have 90% power to detect a 5% absolute risk reduction.

DISCUSSION

HUS is a devastating illness with no treatment options. This pragmatic study will determine if hyperhydration can reduce morbidity associated with HUS in children with high-risk STEC infection.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05219110 . Registered on February 1, 2022.

Health Services Use and Outcomes for Hospital Admissions With a Major Cardiovascular Event Recorded in Health Care Administrative Data in Patients Receiving Maintenance Hemodialysis: A Retrospective Cohort Study

Background

Administrative data are used in studies of hemodialysis care to report cardiovascular-related hospitalizations. Showing recorded events are associated with significant health care resource use and poor outcomes would confirm that administrative data algorithms identify clinically meaningful events.

Objective

The objective of this study was to describe the 30-day health service use and outcomes when a hospital admission with myocardial infarction, congestive heart failure, or ischemic stroke is recorded in administrative databases.

Design

This is a retrospective review of linked administrative data.

Patients and Setting

Patients receiving maintenance in-center hemodialysis in Ontario, Canada, between April 1, 2013, and March 31, 2017, were included.

Measurements

Records from linked health care databases at ICES in Ontario, Canada were considered. We identified hospital admission with the most responsible diagnosis recorded as myocardial infarction, congestive heart failure, or ischemic stroke. We then assessed the frequency of common tests, procedures, consultations, post-discharge outpatient drug prescriptions, and outcomes within 30 days following the hospital admission.

Methods

We used descriptive statistics to summarize results using counts and percentages for categorical variables and means with standard deviations or medians with quartile ranges for continuous variables.

Results

There were 14 368 patients who received maintenance hemodialysis between April 1, 2013, and March 31, 2017. The number of events per 1000 person-years was 33.5 for hospital admissions with myocardial infarction, 34.2 for congestive heart failure, and 12.9 for ischemic stroke. The median (25th, 75th percentile) duration of hospital stay was 5 (3-10) days for myocardial infarction, 4 (2-8) days for congestive heart failure, and 9 (4-18) days for ischemic stroke. The chance of death within 30 days was 21% for myocardial infarction, 11% for congestive heart failure, and 19% for ischemic stroke.

Limitations

Events, procedures, and tests recorded in administrative data can be misclassified compared with medical charts.

Conclusions

In patients receiving maintenance hemodialysis, hospital admissions of major cardiovascular events routinely recorded in health administrative databases are associated with significant use of health service resources and poor health outcomes.

Personalised cooler dialysate for patients receiving maintenance haemodialysis (MyTEMP): a pragmatic, cluster-randomised trial

BACKGROUND

Haemodialysis centres have conventionally provided maintenance haemodialysis using a standard dialysate temperature (eg, 36·5°C) for all patients. Many centres now use cooler dialysate (eg, 36·0°C or lower) for potential cardiovascular benefits. We aimed to assess whether personalised cooler dialysate, implemented as centre-wide policy, reduced the risk of cardiovascular-related death or hospital admission compared with standard temperature dialysate.

METHODS

MyTEMP was a pragmatic, two-arm, parallel-group, registry-based, open-label, cluster-randomised, superiority trial done at haemodialysis centres in Ontario, Canada. Eligible centres provided maintenance haemodialysis to at least 15 patients a week, and the medical director of each centre had to confirm that their centre would deliver the assigned intervention. Using covariate-constrained randomisation, we allocated 84 centres (1:1) to use either personalised cooler dialysate (nurses set the dialysate temperature 0·5-0·9°C below each patient's measured pre-dialysis body temperature, with a lowest recommended dialysate temperature of 35·5°C), or standard temperature dialysate (36·5°C for all patients and treatments). Patients and health-care providers were not masked to the group assignment; however, the primary outcome was recorded in provincial databases by medical coders who were unaware of the trial or the centres' group assignment. The primary composite outcome was cardiovascular-related death or hospital admission with myocardial infarction, ischaemic stroke, or congestive heart failure during the 4-year trial period. Analysis was by intention to treat. The study is registered at ClinicalTrials.gov, NCT02628366.

FINDINGS

We assessed all of Ontario's 97 centres for inclusion into the study. Nine centres had less than 15 patients and one director requested that four of their seven centres not participate. 84 centres were recruited and on Feb 1, 2017, these centres were randomly assigned to administer personalised cooler dialysate (42 centres) or standard temperature dialysate (42 centres). The intervention period was from April 3, 2017, to March 31, 2021, and during this time the trial centres provided outpatient maintenance haemodialysis to 15 413 patients (about 4·3 million haemodialysis treatments). The mean dialysate temperature was 35·8°C in the cooler dialysate group and 36·4°C in the standard temperature group. The primary outcome occurred in 1711 (21·4%) of 8000 patients in the cooler dialysate group versus 1658 (22·4%) of 7413 patients in the standard temperature group (adjusted hazard ratio 1·00, 96% CI 0·89 to 1·11; p=0·93). The mean drop in intradialytic systolic blood pressure was 26·6 mm Hg in the cooler dialysate group and 27·1 mm Hg in the standard temperature group (mean difference -0·5 mm Hg, 99% CI -1·4 to 0·4; p=0·14).

INTERPRETATION

Centre-wide delivery of personalised cooler dialysate did not significantly reduce the risk of major cardiovascular events compared with standard temperature dialysate. The rising popularity of cooler dialysate is called into question by this study, and the risks and benefits of cooler dialysate in some patient populations should be clarified in future trials.

FUNDING

Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Ontario Renal Network, Ontario Strategy for Patient-Oriented Research Support Unit, Dialysis Clinic, Inc., ICES (formerly known as the Institute for Clinical Evaluative Sciences), Lawson Health Research Institute, and Western University.

Using a Human Circulation Mathematical Model to Simulate the Effects of Hemodialysis and Therapeutic Hypothermia

Background: We developed a hemodynamic mathematical model of human circulation coupled to a virtual hemodialyzer. The model was used to explore mechanisms underlying our clinical observations involving hemodialysis. Methods: The model consists of whole body human circulation, baroreflex feedback control, and a hemodialyzer. Four model populations encompassing baseline, dialysed, therapeutic hypothermia treated, and simultaneous dialysed with hypothermia were generated. In all populations atrial fibrillation and renal failure as co-morbidities, and exercise as a treatment were simulated. Clinically relevant measurables were used to quantify the effects of each in silico experiment. Sensitivity analysis was used to uncover the most relevant parameters. Results: Relative to baseline, the modelled dialysis increased the population mean diastolic blood pressure by 5%, large vessel wall shear stress by 6%, and heart rate by 20%. Therapeutic hypothermia increased systolic blood pressure by 3%, reduced large vessel shear stress by 15%, and did not affect heart rate. Therapeutic hypothermia reduced wall shear stress by 15% in the aorta and 6% in the kidneys, suggesting a potential anti-inflammatory benefit. Therapeutic hypothermia reduced cardiac output under atrial fibrillation by 12% and under renal failure by 20%. Therapeutic hypothermia and exercise did not affect dialyser function, but increased water removal by approximately 40%. Conclusions: This study illuminates some mechanisms of the action of therapeutic hypothermia. It also suggests clinical measurables that may be used as surrogates to diagnose underlying diseases such as atrial fibrillation.

"Is It Removed During Dialysis?"-Cognitive Dysfunction in Advanced Kidney Failure-A Review Article

Cognitive impairment is independently associated with kidney disease and increases in prevalence with declining kidney function. At the stage where kidney replacement therapy is required, with dialysis or transplantation, cognitive impairment is up to three times more common, and can present at a younger age. This is not a new phenomenon. The cognitive interactions of kidney disease are long recognized from historical accounts of uremic encephalopathy and so-called "dialysis dementia" to the more recent recognition of cognitive impairment in those undergoing kidney replacement therapy (KRT). The understanding of cognitive impairment as an extra-renal complication of kidney failure and effect of its treatments is a rapidly developing area of renal medicine. Multiple proposed mechanisms contribute to this burden. Advanced vascular aging, significant multi-morbidity, mood disorders, and sleep dysregulation are common in addition to the disease-specific effects of uremic toxins, chronic inflammation, and the effect of dialysis itself. The impact of cognitive impairment on people living with kidney disease is vast ranging from increased hospitalization and mortality to decreased quality of life and altered decision making. Assessment of cognition in patients attending for renal care could have benefits. However, in the context of a busy clinical service, a pragmatic approach to assessing cognitive function is necessary and requires consideration of the purpose of testing and resources available. Limited evidence exists to support treatments to mitigate the degree of cognitive impairment observed, but promising interventions include physical or cognitive exercise, alteration to the dialysis treatment and kidney transplantation. In this review we present the history of cognitive impairment in those with kidney failure, and the current understanding of the mechanisms, effects, and implications of impaired cognition. We provide a practical approach to clinical assessment and discuss evidence-supported treatments and future directions in this ever-expanding area which is pivotal to our patients' quality and quantity of life.

Cardiovascular Safety of Metoclopramide Compared to Domperidone: A Population-Based Cohort Study

BACKGROUND

Metoclopramide and domperidone are common prokinetics used to alleviate gastrointestinal symptoms. However, both drugs may trigger ventricular arrhythmias.

AIM

We conducted this population-based study to compare the 30-day cardiovascular safety of metoclopramide versus domperidone in outpatient care.

METHODS

We used health care databases to identify a cohort of patients in Ontario, Canada newly dispensed metoclopramide or domperidone. Inverse probability of treatment weighting based on propensity scores was used to balance the baseline characteristics of the two groups. All outcomes were assessed in the 30 days following drug dispensing. The primary outcome was hospital encounter with ventricular arrhythmia. The secondary outcomes were hospital encounter with cardiac arrest, all-cause mortality and cardiovascular mortality.

RESULTS

We identified 196,544 patients, 19% of whom were prescribed metoclopramide. There was no difference in the risk of a hospital encounter with ventricular arrythmia (0.02% in both groups), or cardiac arrest (0.10% with metoclopramide and 0.08% with domperidone). However, 1.34% of patients died after starting metoclopramide compared to 0.52% of patients starting domperidone; weighted risk ratio 2.50 (95% confidence interval [CI] 2.13 to 3.03). Similarly, 0.42% of patients died of cardiovascular causes after starting metoclopramide compared to 0.19 % of patients starting domperidone; weighted risk ratio 2.00 (95% CI 1.44 to 2.77).

CONCLUSION

The 30-day risk for a hospital encounter with ventricular arrhythmia was low for both metoclopramide and domperidone, with no significant difference in the rate between the two drugs. The higher 30-day risk of death observed with metoclopramide compared with domperidone in this study has also been observed in other studies and warrants further investigation.

Simple compared to covariate-constrained randomization methods in balancing baseline characteristics: a case study of randomly allocating 72 hemodialysis centers in a cluster trial

Background and aim

Some parallel-group cluster-randomized trials use covariate-constrained rather than simple randomization. This is done to increase the chance of balancing the groups on cluster- and patient-level baseline characteristics. This study assessed how well two covariate-constrained randomization methods balanced baseline characteristics compared with simple randomization.

Methods

We conducted a mock 3-year cluster-randomized trial, with no active intervention, that started April 1, 2014, and ended March 31, 2017. We included a total of 11,832 patients from 72 hemodialysis centers (clusters) in Ontario, Canada. We randomly allocated the 72 clusters into two groups in a 1:1 ratio on a single date using individual- and cluster-level data available until April 1, 2013. Initially, we generated 1000 allocation schemes using simple randomization. Then, as an alternative, we performed covariate-constrained randomization based on historical data from these centers. In one analysis, we restricted on a set of 11 individual-level prognostic variables; in the other, we restricted on principal components generated using 29 baseline historical variables.

We created 300,000 different allocations for the covariate-constrained randomizations, and we restricted our analysis to the 30,000 best allocations based on the smallest sum of the penalized standardized differences. We then randomly sampled 1000 schemes from the 30,000 best allocations. We summarized our results with each randomization approach as the median (25th and 75th percentile) number of balanced baseline characteristics. There were 156 baseline characteristics, and a variable was balanced when the between-group standardized difference was ≤ 10%.

Results

The three randomization techniques had at least 125 of 156 balanced baseline characteristics in 90% of sampled allocations. The median number of balanced baseline characteristics using simple randomization was 147 (142, 150). The corresponding value for covariate-constrained randomization using 11 prognostic characteristics was 149 (146, 151), while for principal components, the value was 150 (147, 151).

Conclusion

In this setting with 72 clusters, constraining the randomization using historical information achieved better balance on baseline characteristics compared with simple randomization; however, the magnitude of benefit was modest.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05590-1.

MyTEMP: Statistical Analysis Plan of a Registry-Based, Cluster-Randomized Clinical Trial

Background:

Major Outcomes with Personalized Dialysate TEMPerature (MyTEMP) is a 4-year cluster-randomized clinical trial comparing the effect of using a personalized, temperature-reduced dialysate protocol versus a dialysate temperature of 36.5°C on cardiovascular-related death and hospitalization. Randomization was performed at the level of the dialysis center (“the cluster”).

Objective:

The objective is to outline the statistical analysis plan for the MyTEMP trial.

Design:

MyTEMP is a pragmatic, 2-arm, parallel-group, registry-based, open-label, cluster-randomized trial.

Setting:

A total of 84 dialysis centers in Ontario, Canada.

Patients:

Approximately 13 500 patients will have received in-center hemodialysis at the 84 participating dialysis centers during the trial period (April 3, 2017, to March 1, 2021, with a maximum follow-up to March 31, 2021).

Methods:

Patient identification, baseline characteristics, and study outcomes will be obtained primarily through Ontario administrative health care databases held at ICES. Covariate-constrained randomization was used to allocate the 84 dialysis centers (1:1) to the intervention group or the control group. Centers in the intervention group used a personalized, temperature-reduced dialysate protocol, and centers in the control group used a fixed dialysate temperature of 36.5°C.

Outcomes:

The primary outcome is a composite of cardiovascular-related death or major cardiovascular-related hospitalization (defined as a hospital admission with myocardial infarction, congestive heart failure, or ischemic stroke) recorded in administrative health care databases. The key secondary outcome is the mean drop in intradialytic systolic blood pressure, defined as the patients’ predialysis systolic blood pressure minus their nadir systolic blood pressure during the dialysis treatment. Anonymized data on patients’ predialysis and intradialytic systolic blood pressure were collected at monthly intervals from each dialysis center.

Analysis plan:

The primary analysis will follow an intent-to-treat approach. The primary outcome will be analyzed at the patient level as the hazard ratio of time-to-first event, estimated from a subdistribution hazards model. Within-center correlation will be accounted for using a robust sandwich estimator. In the primary analysis, patients’ observation time will end if they experience the primary outcome, emigrate from Ontario, or die of a noncardiovascular cause (which will be treated as a competing risk event). The between-group difference in the mean drop in intradialytic systolic blood pressure obtained during the dialysis sessions throughout the trial period will be analyzed at the center level using an unadjusted random-effects linear mixed model.

Trial status:

The MyTEMP trial period is April 3, 2017, to March 31, 2021. We expect to analyze and report results by 2023 once the updated data are available at ICES.

Trial registration:

MyTEMP is registered with the US National Institutes of Health at clincaltrials.gov (NCT02628366).

Statistical analytic plan:

Version 1.1 June 15, 2021.

Therapeutic Hypothermia Reduces Peritoneal Dialysis Induced Myocardial Blood Flow Heterogeneity and Arrhythmia

Background: Moderate therapeutic hypothermia (TH) is a well-recognized cardio-protective strategy. The instillation of fluid into the peritoneum provides an opportunity to deliver moderate hypothermia as primary prevention against cardiovascular events. We aimed to to investigate both cardiac perfusion consequences (overall blood flow and detailed assessment of perfusion heterogeneity) and subsequently simulate the associated arrhythmic risk for patients undergoing peritoneal dialysis (PD) induced TH. Methods: Patients underwent high resolution myocardial perfusion scanning using high resolution 256 slice CT scanning, at rest and with adenosine stress. The first visit using the patient's usual PD regimen, on the second visit the same regime was utilized but with cooled peritoneal dialysate at 32°C. Myocardial blood flow (MBF) was quantified from generated perfusion maps, reconstructed in 3D. MBF heterogeneity was assessed by fractal dimension (FD) measurement on the 3D left ventricular reconstruction. Arrhythmogenicity was quantified from a sophisticated computational simulation using a multi-scale human 3D ventricle wedge electrophysiological computational model. Results: We studied 7 PD patients, mean age of 60 ± 7 and mean vintage dialysis of 23.6 ± 17.6 months. There were no significant different in overall segmental MBF between normothermic condition (NT) and TH. MBF heterogeneity was significantly decreased (-14%, p = 0.03) at rest and after stress (-14%, p = 0.03) when cooling was applied. Computational simulation showed that TH allowed a normalization of action potential, QT duration and T wave. Conclusion: TH-PD results in moderate hypothermia leading to a reduction in perfusion heterogeneity and simulated risk of non-terminating malignant ventricular arrhythmias.

A Review on the Application and Limitations of Administrative Health Care Data for the Study of Acute Kidney Injury Epidemiology and Outcomes in Children

Administrative health care databases contain valuable patient information generated by health care encounters. These "big data" repositories have been increasingly used in epidemiological health research internationally in recent years as they are easily accessible and cost-efficient and cover large populations for long periods. Despite these beneficial characteristics, it is also important to consider the limitations that administrative health research presents, such as issues related to data incompleteness and the limited sensitivity of the variables. These barriers potentially lead to unwanted biases and pose threats to the validity of the research being conducted. In this review, we discuss the effectiveness of health administrative data in understanding the epidemiology of and outcomes after acute kidney injury (AKI) among adults and children. In addition, we describe various validation studies of AKI diagnostic or procedural codes among adults and children. These studies reveal challenges of AKI research using administrative data and the lack of this type of research in children and other subpopulations. Additional pediatric-specific validation studies of administrative health data are needed to promote higher volume and increased validity of this type of research in pediatric AKI, to elucidate the large-scale epidemiology and patient and health systems impacts of AKI in children, and to devise and monitor programs to improve clinical outcomes and process of care.

Intradialytic Hypotension and Newly Recognized Peripheral Artery Disease in Patients Receiving Hemodialysis

RATIONALE & OBJECTIVE

Intradialytic hypotension (IDH) may decrease systemic circulation to the legs, exacerbating symptoms of peripheral artery disease (PAD). We sought to evaluate the relationship between IDH and newly recognized lower extremity PAD among hemodialysis patients.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Linking data from the US Renal Data System to the electronic health records of a large dialysis provider, we identified adult patients (≥18 years of age) with Medicare Parts A and B who initiated dialysis (2006-2011) without previously recognized PAD.

EXPOSURE

The time-varying proportion of hemodialysis sessions with IDH defined as the nadir intradialytic systolic blood pressure <90 mm Hg. We categorized the proportion of sessions with IDH within serial 30-day intervals as 0%, >0% to <15%, 15% to <30%, and ≥30%.

OUTCOMES

Newly recognized PAD was ascertained using PAD diagnostic and procedure codes for amputation or revascularization, in serial 30-day intervals subsequent to each 30-day exposure interval.

ANALYTICAL APPROACH

To account for the competing risks of death and kidney transplantation, we estimated unadjusted and adjusted subdistribution hazard ratios using the Kaplan-Meier multiple imputation method in combination with the extended Cox model to account for IDH as a time-varying exposure.

RESULTS

Among 45,591 patients, those with more frequent baseline IDH had a higher prevalence of cardiovascular diseases. During 61,725 person-years of follow-up, 7,886 patients had newly recognized PAD. We found a graded, direct association between IDH and newly recognized PAD. For example, having IDH in ≥30% of dialysis sessions during a given 30-day interval (vs 0%) was associated with a 24% (95% CI, 17%-32%) higher hazard than having newly recognized PAD in the subsequent 30 days.

LIMITATIONS

Unmeasured confounding; ascertainment of PAD from claims.

CONCLUSIONS

Patients receiving hemodialysis who had more frequent IDH had higher rates of newly recognized PAD. Patients with frequent IDH may warrant careful examination for PAD.