This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Application of Impedance Threshold Device Technologies to Treat and Prevent Hypotension During Dialysis (NCT00576524), a randomized phase 2 study. The primary outcome is Fluid Removal.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00576524 |
| Phase | Phase 2 |
| Condition | Intradialytic Hypotension, End Stage Renal Disease, Low Blood Pressure |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | Triple |
| Enrollment | 2 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Children's Hospital of Philadelphia |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned children undergoing hemodialysis. Its stated clinical context was intradialytic hypotension, with end stage renal disease and low blood pressure also listed among the conditions. The registry record does not report further eligibility criteria or describe the characteristics of enrolled participants.
Intervention
The intervention was an impedance threshold device, identified as ITD. The study purpose was to evaluate its application during hemodialysis in relation to fluid removal, complications such as cramps, vomiting and hypotension, and device tolerance. The registry record does not report analyzed findings for these questions.
Comparator
The comparator was a sham device. Participants were assigned to a treatment sequence: sham followed by ITD, or ITD followed by sham. The sequence descriptions specify a washout of 7 days. The registry record does not report whether participants completed both parts of an assigned sequence.
Primary question
The primary outcome was fluid removed as a percentage of dry body weight over 6 weeks. The clinical question was whether fluid removal differed with the ITD compared with the sham device during hemodialysis. The registry states that the data were not analyzed because the study closed due to lack of recruitment, so it does not establish an estimated difference or its precision.
3. Trial Design
The registry describes a phase 2, randomized, triple-masked crossover study. In a crossover design, participants are assigned to treatment sequences and may receive each study condition at different times. The registered sequences were sham device first and ITD next, or ITD first and sham device next, with a washout of 7 days between them. The record does not identify which people or roles were masked, or explain how the crossover analysis was intended to account for sequence or period effects.
The sponsor was Children's Hospital of Philadelphia. The recorded study start was 2008-09, and primary completion was recorded as 2011-02. The status is terminated, with lack of recruitment given as the reason the study closed. Registered enrollment was 2. This enrollment figure does not establish how many participants completed treatment periods or contributed outcome data; the registry does not report those details.
The ITD and sham were both listed as device interventions. The primary outcome was fluid removed as a percentage of dry body weight, with a timeframe of 6 weeks. Secondary outcomes were extra days to achieve target dry weight and changes in heart rate and blood pressure measured by a non-invasive cuff. The registry lists 3 outcome measures and 0 analyses. It does not report completed treatment sequences, a participant flow, or an analysis population.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: The study design will consist of a "run-in phase", followed by a randomized, cross-over, clinical "intervention phase" with application of the ITD (sham or -7 cm H2O) in 20 pediatric subjects undergoing regular hemodialysis.
Overall Study
| Stage | ITD First, Sham Device Next | Sham Device First, ITD Next |
|---|---|---|
| STARTED | 2 | 0 |
| COMPLETED | 2 | 0 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Data not analyzed - study closed due to lack of recruitment
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Sham Device | ITD Device | Total |
|---|---|---|---|---|
| Participants analysed | 2 | 0 | 2 | |
| Age Categorical: <=18 years | participants | 2 | — | 2 |
| Age Categorical: Between 18 and 65 years | participants | 0 | — | 0 |
| Age Categorical: >=65 years | participants | 0 | — | 0 |
| Sex: Female, Male: Female | Participants | NA | — | 0 |
| Sex: Female, Male: Male | Participants | NA | — | 0 |
| Region of Enrollment: United States | participants | 2 | — | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Fluid Removal, measured over 6 weeks.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was fluid removed as a percentage of dry body weight, assessed over 6 weeks. It expresses fluid removal relative to a measure of body weight used as a target in dialysis care. Using a percentage rather than a raw volume can make fluid removal interpretable in relation to the participant’s dry body weight. This is a general explanation of the endpoint’s scale, not evidence that the measure was collected or analyzed in this study.
The registry identifies fluid removal as the primary outcome but gives no unit beyond the percentage description and no numerical result. It explicitly states that the data were not analyzed because the study closed due to lack of recruitment. Consequently, no treatment contrast, uncertainty interval, or statistical test for this endpoint is reported. The timeframe is registered as 6 weeks, but the record does not clarify the timing or aggregation of measurements within that interval. It also does not report how dry body weight was determined or how repeated measurements, if any, were to be summarized.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive fact is that the primary outcome was not analyzed. The record therefore does not provide an estimate of fluid removed as a percentage of dry body weight under ITD compared with sham, nor a measure of the precision of such an estimate. There is no basis in the registry record for describing the direction or magnitude of a treatment difference. Lack of an analysis is not evidence that the treatments produced the same outcome.
Recruitment ended with the study terminated for lack of recruitment, and the registry records enrollment of 2. That small recorded enrollment is important context for understanding why the registry offers no analyzed primary result, but it does not by itself establish how many participants completed either treatment condition or had usable outcome measurements. Those details are not reported in the registry record.
The crossover structure could, in principle, allow comparisons within participants, because each sequence assigns the study devices at different times. That design description alone does not establish that a within-participant comparison was completed or that it would be reliable. The registry does not report completion, carryover assessment, period effects, or an analysis method for the crossover. The registered washout was 7 days, but the record does not provide evidence about whether that interval was sufficient for the measured outcomes.
Secondary outcomes include extra days to achieve target dry weight and changes in heart rate and blood pressure measured by a non-invasive cuff. No analyzed findings for these outcomes are reported. The posted record should therefore be read as a description of the study’s intent and design rather than as a source of comparative outcome evidence. Numerical planning illustrations, if consulted, are not observed study effects and cannot substitute for the missing analysis.
9. Statistical Methods Explained
The registry provides a design description but does not report a statistical analysis of the outcome data. The distinctions below explain what the registered design would ordinarily imply and what can, and cannot, be concluded from this record.
What does randomization contribute?
Randomization assigns treatment sequences by a chance-based process. In general, this can reduce systematic differences between groups at assignment, although it cannot guarantee balance in a small study. Here the registered sequences were sham followed by ITD and ITD followed by sham. The record does not describe the randomization procedure, allocation concealment, or whether sequence assignment was implemented as planned. Because outcome data were not analyzed, randomization does not yield a reported treatment-effect estimate.
How does a crossover comparison work?
In general, a crossover study compares treatment conditions across periods within participants, rather than relying only on comparisons between separate groups. This can account for stable participant characteristics when within-person outcomes are available. It also requires attention to changes over time, treatment order, and possible carryover from an earlier condition. The registered washout was 7 days. The registry does not report an analysis that accounts for period or sequence, an assessment of carryover, or whether participants completed both conditions. Thus, the crossover label describes the planned structure, not a completed or verified comparison.
What does masking mean in this record?
The study is listed as triple-masked. Masking can reduce the influence of treatment knowledge on participant experience, clinical decisions, outcome assessment, or analysis, depending on who is masked. The registry record does not specify which roles were masked or how masking was maintained. It also does not report whether masking was assessed. No further claims about the practical success of masking can be drawn from the label alone.
What can an estimate and confidence interval show?
In general, a treatment-effect estimate describes the observed contrast between conditions, while a confidence interval describes the statistical uncertainty around that estimate under the analysis assumptions. A narrow interval indicates greater precision than a wide interval, but neither an estimate nor an interval alone establishes clinical importance. This record gives no analyzed primary estimate or confidence interval. Accordingly, there is no reported precision measure to interpret and no statistical basis for describing the size of a primary treatment contrast.
Why can over-dispersion matter?
For outcomes such as counts, the observed variability can exceed what a simple statistical model assumes. This is called over-dispersion. In general, failing to account for it can make standard errors too small and uncertainty appear less than it is. The registry does not report a count-model analysis or indicate that over-dispersion was assessed. This concept is relevant only as a general statistical consideration; it is not a finding about this study.
How should planning calculations be understood?
The recorded planning assumptions describe a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. They also describe the effect for planning as a stated fraction of an observed effect. Such calculations are planning illustrations, not observed power and not evidence that a study detected an effect. The registry does not report an analyzed primary effect from this trial, so a planning illustration cannot be treated as a trial result. The record also does not report the trial’s own sample-size justification or a protocol-based power target.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 3 outcome measures: fluid removed as a percentage of dry body weight, extra days to achieve target dry weight, and changes in heart rate and blood pressure measured by a non-invasive cuff. The primary outcome is identified, but the record does not report a statistical analysis for it or for the secondary outcomes. It lists 0 analyses.
When a study examines multiple outcomes, time points, or comparisons, the chance of finding an apparently notable result by chance can increase. Statistical methods for handling this issue are commonly called multiplicity adjustments or multiplicity strategies. The registry record does not report whether a multiplicity strategy was planned or used. It also does not give enough detail about outcome time points or planned comparisons to reconstruct a testing family. No conclusion about adjusted or unadjusted statistical significance is possible from the record.
The primary outcome description says the data were not analyzed because the study closed due to lack of recruitment. Missing outcome values, reasons for missingness, and the handling of missing data are not reported in the registry record. The analysis population is also not reported: there is no description of whether analyses were intended to include all randomized participants, participants who received a device, or participants who completed both treatment periods. Without these details and without an analysis, the record cannot establish whether missingness or exclusions would have affected a treatment comparison.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Sham Device | 0 | 2 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Sham Device | 0 of 2 |
| ITD Device | 0 of 0 |
The registry reports serious and other adverse-event figures separately for the sham and ITD device groups. For sham, 2 were listed at risk for serious adverse events and 0 were affected; 2 were listed at risk for other adverse events and 0 were affected. For ITD, 0 were listed at risk for either category, and 0 were affected in each category. Death figures are not reported in the registry record.
These fields are counts, not comparative rates. In particular, the ITD group has 0 listed at risk in the adverse-event fields, so its zero affected count should not be interpreted as evidence that no adverse events occurred among people exposed to ITD. The record does not explain the group denominators, exposure, observation time, or whether these figures reflect a complete safety assessment. The numbers therefore do not support a reliable comparison of safety between devices. They should be read alongside the trial’s terminated status and the absence of analyzed outcome data, without treating an affected count of 0 as proof of absence of risk.
12. What the Result Does, and Does Not, Mean
This registry record documents an intended randomized, triple-masked crossover comparison of an ITD with a sham device during hemodialysis in children. It identifies a primary endpoint and secondary outcomes, and describes the treatment sequences and washout. It also records enrollment of 2 and states that the study closed because of lack of recruitment. Most importantly for interpreting results, the primary outcome data were not analyzed.
The record does not show whether the ITD changed fluid removal, how large any difference might have been, or how precisely such a difference could be estimated. It likewise does not provide analyzed results for the secondary outcomes. The absence of reported results should not be interpreted as a finding of no effect, equivalence, or safety. It means that the registry does not provide an analyzed comparison with which to answer those questions.
The design can still be informative about the intended scientific question: the study planned to compare two device conditions using treatment sequences and a washout of 7 days. But design intent is different from evidence obtained from analyzed data. The registry does not report the actual completion of sequences, the analysis population, or methods for handling missing data and crossover effects. Those gaps limit what can be inferred about both efficacy and safety.
Any planning calculation is a statistical illustration rather than observed power or a clinical result. The record does not report an analyzed effect that could support a substantive interpretation. The appropriate conclusion is therefore narrow: the trial was registered with a comparative objective, but its posted record does not establish an outcome difference between ITD and sham.
13. Why This Trial Matters Statistically
This study matters statistically because its design and outcome question are clearly registered, while its record also illustrates the limits imposed by recruitment and the absence of analysis. The crossover approach was intended to compare ITD and sham across treatment sequences in children undergoing hemodialysis. That structure could support within-participant comparisons in a completed study, but it depends on collected outcomes and an analysis that addresses period, sequence, and potential carryover. The registry does not report such an analysis.
The primary endpoint—fluid removed as a percentage of dry body weight—connects the statistical comparison to a clinically relevant process measure identified by the study. Yet a well-defined endpoint is not itself a result. Without analyzed values and an estimate of uncertainty, readers cannot determine whether observed differences were small or large, or whether the data were sufficiently precise to distinguish among plausible effects.
The record also demonstrates why denominators matter in safety interpretation. The sham group has participants listed at risk, while the ITD group has none listed at risk in these adverse-event fields. Consequently, the zero affected count for ITD cannot support a like-for-like safety comparison. Clear reporting of exposure and analysis populations would be needed for that interpretation.
More broadly, termination for lack of recruitment can leave a study unable to answer its intended question. Statistical planning illustrations cannot replace observed outcomes, and a design label cannot establish that the planned comparison occurred. The record is useful for understanding the intended trial, but it does not provide comparative evidence about the registered outcomes.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The main trial-specific limitation is that recruitment was insufficient for the study to proceed to analysis, and the registry explicitly says the primary outcome data were not analyzed. Although enrollment is recorded as 2, the record does not describe participant flow, treatment exposure, completion of the crossover sequences, or the availability of endpoint measurements. The registry therefore does not show what data, if any, were collected for each outcome.
The outcome definition is limited: fluid removed is described as a percentage of dry body weight over 6 weeks, but measurement timing, aggregation, and handling of repeated measurements are not reported. The registry also does not state how target dry weight was determined. For the crossover, it gives the sequence options and a washout of 7 days, but does not report an assessment of carryover or a plan for period and sequence effects.
Other important details are not reported in the registry record, including the randomization procedure, the roles covered by triple masking, a statistical analysis plan, missing-data methods, the analysis population, and a sample-size justification. The listed adverse-event figures do not clarify exposure or observation time, and death figures are not reported. Together, these limitations prevent a reliable treatment-effect or safety comparison from being reconstructed from the registry entry.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Application of Impedance Threshold Device Technologies to Treat and Prevent Hypotension During Dialysis — NCT00576524.
- Registry record last updated 2013-02-26; status last verified 2013-01.
- Results first posted 2013-02-26.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT00576524 is a phase 2 randomized, triple-masked crossover study of an ITD device compared with a sham device during hemodialysis in children. The registered sequences place sham or ITD first, followed by the other device after a washout of 7 days. The primary outcome is fluid removed as a percentage of dry body weight over 6 weeks; registered secondary outcomes concern days to target dry weight and heart rate and blood pressure.
The record lists enrollment of 2, a terminated status, and lack of recruitment as the reason for closure. It states that the primary outcome data were not analyzed and lists 0 analyses. Thus, the registry describes the intended comparison but reports no analyzed treatment effect or precision estimate. The adverse-event fields do not provide a balanced basis for comparing devices, and death figures are not reported in the registry record.