Clinical Study of Asahi ViE Dialyzer in Canada: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Study of Asahi ViE Dialyzer in Canada (NCT02292212), a na na study. The primary outcome is Removal Rate of Urea.

2. Clinical Question

The study was designed to obtain performance data on the ViE-21 dialyzer. For the primary measure, blood samples were collected before and after dialysis. The removal rate was calculated from the pre-dialysis and post-dialysis urea concentrations. A session in the first week with the control dialyzer provided the pre-ViE measurement; one session at each of weeks 7 and 13 provided measurements during the ViE phase.

The clinical question is therefore about measured urea removal across study phases, not about a randomized comparison of separate treatment groups. Because the intervention followed the conventional-dialyzer phase for all participants, any phase difference would also occur alongside the passage of time and the sequence of treatment. The registry record does not report numerical primary-outcome estimates, so the direction and precision of any observed change cannot be assessed from the record.

3. Trial Design

This was a completed, single-group device study of the ViE-21 dialyzer in Canada. The registry lists 17 enrolled participants and identifies chronic kidney failure as the condition under study. It describes a planned sequence in which the dialyzer was changed from a conventional one to ViE-21 for 36 sessions for all enrolled subjects. The study purpose was to obtain performance data on ViE-21.

The primary endpoint was assessed in a pre-ViE phase and a ViE phase. The pre-ViE measurement was taken during one session in the first week with the control dialyzer. Measurements during the ViE phase were taken at one session in week 7 and one session in week 13. These are repeated phase measurements within a single-group design; the registry does not describe a parallel group assigned to continue the conventional dialyzer.

The registry lists allocation as NA and masking as none. It lists the model as single group and the phase as NA. Accordingly, the design does not provide a randomized, masked comparison between independent groups. A pre-intervention phase offers a within-study reference, but it cannot by itself separate a dialyzer-related difference from other changes that occur over time or in the order of study phases.

The primary-outcome description identifies an ITT population of 14 patients who received at least 30 treatments with ViE-21. The record does not explain the reason for this population definition or describe further analysis populations. Although the study is marked completed, the registry record does not report the numerical primary endpoint results or analysis entries.

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.

Pre-ViE Phase

ViE Phase

Reasons for not completing this period:

Post-ViE Phase

Analysis population for the primary outcome, as defined in the registry: The Intent To Treat (ITT) was based on 14 patients that received at least 30 treatments with ViE-21.

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.

6. Primary Endpoint

The registry lists the primary outcome as Removal Rate of Urea, measured over Week 1 (Pre-ViE phase), 7, 13 (ViE phase).

The primary endpoint is the removal rate of urea, expressed as a percentage of urea removal. It is a continuous measure: each session’s rate is calculated from the urea concentration before dialysis (Cpre) and after dialysis (Cpost), using the stated equation: (Cpre - Cpost) / Cpre × 100. The measure captures the within-session change in urea concentration relative to its pre-dialysis level.

The registry describes sampling at one session in the first week with the control dialyzer, followed by one session in each of weeks 7 and 13 with ViE-21. The stated summary parameter is the mean, with standard deviation as the dispersion measure. A mean conveys the average measured removal rate in the analyzed population; a standard deviation describes how spread out individual measurements are around that mean. Neither statistic, by itself, describes every participant’s result.

Urea removal is used as a performance measure for the dialyzer, consistent with the stated study purpose of obtaining performance data on ViE-21. The registry record does not report the mean or standard deviation at the specified time points, nor does it report a numerical comparison between phases. Consequently, the endpoint definition and measurement schedule are available, but the size and precision of the observed results are not.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous because it is measured on a numerical scale rather than as a yes-or-no event. The registry specifies the mean as its summary parameter and the standard deviation as its measure of dispersion. In general, the mean describes the central level of a set of measurements, while the standard deviation describes how variable those measurements are around the mean. Both are useful for characterizing a continuous outcome, but neither gives a complete picture of individual observations.

How is the endpoint calculated?

For each sampled dialysis session, the registry defines removal rate as the difference between pre-dialysis and post-dialysis urea concentration, divided by the pre-dialysis concentration and multiplied by 100. Cpre is the pre-dialysis concentration; Cpost is the post-dialysis concentration. Expressing the result as a percentage relates the change during the session to the concentration before dialysis. This definition describes the measurement; it does not provide the study’s observed rates.

The planned sampling schedule includes one session in the first week with the control dialyzer and one session at each of weeks 7 and 13 with ViE-21. The endpoint is therefore based on selected sessions at specified phases, rather than a registry-reported summary of every treatment session. The record does not report how the selected sessions or missing samples were handled in the analysis.

What does a phase comparison represent?

The study is single group, with participants changing from the conventional dialyzer to ViE-21. In general, repeated measurements can help describe how an outcome changes within a group over time. However, when the phases occur in a fixed sequence, an observed difference cannot automatically be attributed to the device. Time, phase order, or other changes during the study may coincide with the intervention. A randomized concurrent comparator can help address some of these concerns, but this registry describes no such group.

The registry lists allocation as NA and masking as none. It does not report a statistical model or an adjusted analysis for the primary outcome. In the absence of those details and numerical results, readers cannot assess whether the reported comparison, if any, accounted for repeated measurements or other sources of variation.

Why does variability matter?

In general, participants’ measurements may vary, even when collected using the same endpoint definition. The mean summarizes the average, while the standard deviation indicates the spread around it. Greater variability makes an average less representative of any one participant and can make a group estimate less precise. A confidence interval, when reported, describes a range of values compatible with the data under the analysis assumptions and conveys uncertainty around an estimate. The registry record does not report confidence intervals for the primary endpoint.

Some continuous outcomes can show more variability than a simple model assumes. In general, over-dispersion means the observed variability exceeds what the statistical model expects. When relevant, it can make standard errors too small if not addressed. The registry record does not identify an over-dispersion assessment or report a model for the primary endpoint, so it is not possible to determine whether this issue arose or how it was handled.

What can the planning calculations say?

In general, sample-size illustrations based on an observed effect are planning tools: they describe the sample size that might be needed under specified assumptions to detect an effect of a stated size. They are not observed power and do not show that the completed study had a particular probability of detecting an effect. The stated illustration assumptions include a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a fraction of the observed effect. The study itself is single group, so such an illustration does not change its design into a two-arm trial.

The record does not report the numerical primary effect estimate or the sample-size illustration values in the registry record for this analysis. It also does not report the trial’s own sample-size justification, an interim analysis plan, a statistical analysis plan, a hypothesis test, or a p-value for the primary endpoint. Each of those items is not reported in the registry record. Without an observed estimate and its uncertainty, no recalculated comparison or precision assessment can be made.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Pre-ViE Phase", "ViE Phase (1)", "ViE Phase (2)")
n   <- c(14, 14, 14)
m   <- c(76.1, 74.4, 73.5)
sp  <- c(5.4, 8.8, 4.5)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Pre-ViE Phase  14  76.100  5.400  72.982  79.218
CARM  ViE Phase (1)  14  74.400  8.800  69.319  79.481
CARM  ViE Phase (2)  14  73.500  4.500  70.902  76.098

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 9 outcome measures and identifies device malfunctions as a secondary outcome. It does not report analysis entries. The record does not describe how many endpoints were tested, which were designated for formal hypothesis testing, or how the analysis handled the possibility of multiple comparisons. A multiplicity adjustment or testing hierarchy is not reported in the registry record.

In general, examining multiple outcomes or time points can increase the chance of finding an apparently notable result by chance if each is tested separately. A prespecified analysis plan can clarify which outcomes are primary, how comparisons are organized, and whether adjustments are needed. The registry defines removal of urea as the primary outcome and specifies measurements at the pre-ViE phase and during weeks 7 and 13, but it does not provide enough analysis detail to assess the treatment of multiple comparisons.

The primary-outcome population is described as 14 patients who received at least 30 treatments with ViE-21, while enrollment is listed as 17. The record does not explain why the primary population is defined this way, say how many measurements were available at each time point, or describe exclusions and missing-data methods. Although the outcome description calls the population ITT, the stated treatment threshold is part of that definition; the record does not provide further clarification about how it was applied.

In general, missing-data methods matter because results can be affected if participants with unavailable measurements differ from those with observed measurements. The registry does not report imputation, complete-case methods, sensitivity analyses, or reasons for missing primary-outcome measurements. These details, along with the statistical analysis plan, are not reported in the registry record.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: vertigo (7.1%).

The registry reports serious adverse events separately for the Pre-ViE, ViE, and Post-ViE phases. No participants are listed as affected by a serious adverse event in the Pre-ViE or ViE phase; one participant is listed as affected in the Post-ViE phase. The corresponding numbers at risk are 17 in each of the first two phases and 14 in the Post-ViE phase. No deaths are listed in any phase.

The record lists vertigo at 7.1% among the top serious adverse-event terms. That term listing should be read alongside the phase-level counts, not as a causal conclusion. The registry does not report a randomized safety comparison, and the phases occur in sequence. The counts are descriptive and do not establish whether the device caused an event or whether event risk differed between phases.

Other adverse events are also listed by phase: 16 affected participants in the Pre-ViE phase, 17 in the ViE phase, and 11 in the Post-ViE phase, with the at-risk counts given for each phase. These figures describe the registry’s phase entries; they should not be interpreted as independent parallel-group estimates. The record does not report further information about event timing, severity beyond the serious-event classification, or statistical comparisons.

13. What the Result Does, and Does Not, Mean

The record establishes that the study was completed and that its primary question concerned urea removal during dialysis with ViE-21, measured against a pre-ViE phase. It also specifies how removal rate was defined and when the sessions were sampled. This is useful information about the intended measurement and the context in which it was collected.

However, the record does not report the numerical primary endpoint results. It therefore does not show the mean removal rate, its variability, or the size and precision of any phase difference. The outcome definition alone cannot establish what the observed measurements were. Nor can it support a conclusion about the magnitude of a change attributable to ViE-21.

The design also sets limits on interpretation. Participants changed dialyzers in sequence within a single group, rather than being allocated to concurrent randomized groups. In general, a sequential comparison may reflect time or other changes along with the intervention. The registry does not report an analysis that addresses these possibilities.

The safety entries provide descriptive counts by phase, including one participant with a serious adverse event in the Post-ViE phase and no deaths listed. These figures do not establish causation or comparative risk. More detailed event-level information and a statistical safety comparison are not reported in the registry record.

Thus, the registry supports a description of the study design, endpoint, and reported safety counts, but it does not allow an assessment of the primary outcome’s observed value or uncertainty. The absence of numerical results in the record should not be mistaken for evidence that the endpoint showed no difference or that no events occurred.

14. Why This Trial Matters Statistically

This study is statistically notable because it illustrates the distinction between a clearly defined outcome and a reported outcome result. The registry explains how urea removal was calculated, identifies a mean and standard deviation as the intended summaries, and specifies sampling during the pre-ViE and ViE phases. Yet the numerical results are not reported in the registry record. A precise endpoint definition is important, but it cannot replace estimates and uncertainty measures when readers need to understand what the data showed.

The single-group sequence also highlights a core design issue. A within-participant reference can provide context for later measurements, but a fixed before-and-after sequence does not offer the same protection against time-related differences as a randomized concurrent comparison. The study design should therefore shape the strength and scope of any interpretation, even if numerical results become available elsewhere.

The difference between enrollment and the primary-outcome population is another important reporting feature. The registry lists 17 enrolled participants and describes the primary population as 14 patients meeting a treatment threshold. Clear reporting of eligibility for analysis, outcome availability, and missing-data handling helps readers judge how results relate to the enrolled group. Those details are not reported in the registry record.

Finally, safety counts and the primary performance endpoint answer different questions. Phase-level adverse-event counts are descriptive and do not establish a comparative safety effect, while urea removal is a continuous performance measure. Reading each in light of the design and available analysis details avoids treating registry counts as stronger evidence than they provide.

15. 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 limitation for interpreting this study from the registry is the absence of numerical primary-outcome results. Means, standard deviations, estimates of phase differences, and confidence intervals are not reported in the registry record. The record lists no analysis entries, so statistical tests and adjusted results cannot be assessed.

The single-group, sequential design limits causal interpretation. All enrolled subjects changed from a conventional dialyzer to ViE-21; the record does not describe random allocation to a concurrent comparison group. A phase difference, if reported, could coincide with changes over time or the sequence of study phases. The registry does not report methods to address such factors.

The primary endpoint was sampled during selected sessions: one in the first week with the control dialyzer and one each at weeks 7 and 13 with ViE-21. The record does not report whether these measurements were available for every participant in the stated endpoint population or how unavailable measurements were handled. It also does not explain the primary population definition of 14 patients who received at least 30 ViE-21 treatments, despite listing 17 enrolled participants.

The registry reports no statistical analysis plan, multiplicity approach, interim-analysis information, or sample-size justification. Further details about the conduct of outcome analyses, the timing and handling of adverse events, and reasons for missing measurements are not reported in the registry record. These limitations constrain both assessment of precision and interpretation of the phase-based safety counts.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Clinical Study of Asahi ViE Dialyzer in Canada — NCT02292212.
• Registry record last updated 2019-12-11; status last verified 2019-11.
• Results first posted 2017-08-17.
• 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.

19. Record Summary

NCT02292212 is a completed, single-group device study titled “Clinical Study of Asahi ViE Dialyzer in Canada.” It concerns chronic kidney failure and was sponsored by Asahi Kasei Medical Co., Ltd. The registry lists 17 enrolled participants and describes a change from a conventional dialyzer to ViE-21 for 36 sessions for all enrolled subjects.

The primary endpoint is the mean removal rate of urea, expressed as a percentage and summarized with a standard deviation. Sampling was described for one pre-ViE session in the first week and ViE-21 sessions at weeks 7 and 13. The primary-outcome population is described as 14 patients who received at least 30 ViE-21 treatments.

The numerical primary endpoint results and analysis entries are not reported in the registry record. Safety counts are listed by phase, with one serious adverse event affected participant in the Post-ViE phase and no deaths listed. The sequential, nonrandomized design supports descriptive phase reporting but does not provide a concurrent randomized comparison.