Evaluating the Safety and Effectiveness of the InnAVasc Graft for Dialysis Access in Patients With Kidney Failure: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluating the Safety and Effectiveness of the InnAVasc Graft for Dialysis Access in Patients With Kidney Failure (NCT03645681), a na na study. The primary outcome is Secondary Patency of InnAVasc AVG at 6 Months.

2. Clinical Question

3. Trial Design

This was a single-group device study of the InnAVasc arteriovenous graft for hemodialysis access. The registry lists allocation as NA and masking as none. With no separate control arm, the study description does not establish a randomized comparison against another access graft or standard care. The record identifies W.L.Gore & Associates as sponsor and lists the study as terminated.

The registry reports enrollment of 26. The study began on 2019-01-02, and primary completion is listed as 2019-09-28. These dates describe the recorded study timeline; they do not establish how long each participant was followed or whether all participants reached the primary endpoint assessment. The registry record does not report why the study was terminated.

Participants were to receive a surgical implant in the forearm or upper arm. The arm description specifies a straight, soft C configuration in the upper arm, or a looped configuration in the forearm or upper arm. The registry says standard vascular surgical techniques would be used. It does not report whether all enrolled participants received the implant or whether procedures differed from the planned approach.

The primary outcome was a count of participants meeting the definition of secondary patency at 6 months. A further outcome measure is listed, but its details are not available in the registry record described for this analysis. The record does not report the protocol, the statistical analysis plan, the reason for choosing the study size, or whether interim analyses were planned. No conclusions about a comparator or causal treatment effect can be drawn from the single-group design alone.

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: Intraoperative enrollment criteria: Both vessels have been exposed and are deemed appropriate for implantation (i.e. based on the surgeon's opinion, artery is of adequate size, has adequate pulse to support AV access flow and is safely clampable (i.e. artery has lack of significant calcification); and the vein is of adequate size, free of localized sclerosis, and is free of immediate outflow obstruction).

Overall Study

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 Secondary Patency of InnAVasc AVG at 6 Months, measured over at 6 months.

The primary endpoint is titled secondary patency of the InnAVasc graft at 6 months and is measured as a count of participants. The registry defines secondary patency as being free from abandonment, including surgical or endovascular interventions designed to reestablish graft patency, at the 6-month timepoint. The definition therefore captures more than whether the graft remains open without any intervention: a participant is not counted as meeting the endpoint if the graft was abandoned or an intervention to restore patency was performed.

This kind of endpoint can describe whether access remains usable over a specified follow-up period under the study’s definition. It may be relevant to evaluating a dialysis access device because it incorporates both continued use and the need for procedures intended to restore patency. The endpoint’s interpretation depends on consistent assessment of abandonment and patency-restoring interventions, as well as adequate follow-up to the assessment timepoint.

The registry record does not report how many participants met this definition, how many were assessed at 6 months, or how missing endpoint observations were handled. It also does not provide a comparison group. Consequently, the endpoint definition can be explained, but the record does not support a numerical conclusion about the observed secondary-patency outcome or a comparative estimate.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The endpoint is a binary participant-level outcome: each participant either meets the registry’s secondary-patency definition at the specified timepoint or does not. The reported endpoint parameter is a count of participants, rather than a continuous measurement such as a laboratory value. A count is straightforward to describe, but its interpretation requires knowing the population assessed and how participants without an observed assessment were handled. Those details are not reported in the registry record.

What does a single-group result estimate?

In a single-group study, an outcome count describes the experience of participants who received the intervention. It does not directly estimate a difference between treatments. A comparative effect requires outcomes under a comparator, measured in a way that supports a fair comparison. Here, the allocation is listed as NA and the study model is single-group. The registry record does not identify a concurrent control group, so it does not support a randomized treatment contrast.

General statistical interpretation also distinguishes an observed estimate from its uncertainty. A confidence interval is a range of values compatible with the data and a specified statistical procedure; it helps communicate how precisely an outcome has been estimated. A narrow interval generally indicates greater precision than a wide interval, but neither an interval nor a precision estimate is reported for the primary outcome in the registry record. A point estimate alone, if it were reported, would not show how much uncertainty surrounds it.

Why does the endpoint definition matter?

Secondary patency is not simply a statement that the graft was open at one examination. The definition excludes participants whose graft was abandoned and those who had a surgical or endovascular intervention designed to reestablish patency by the assessment timepoint. Endpoint classification therefore depends on procedure and abandonment information over follow-up, as well as the status at the timepoint. Consistent definitions and complete ascertainment are important because differences in how these events are recorded could change who is classified as meeting the endpoint.

Time-to-event methods can be useful when participants have different follow-up durations or when an event occurs before a planned assessment. Such methods require details about event dates, censoring, and follow-up. The primary outcome listed in this record is a participant count at 6 months, and the registry entries do not describe a time-to-event analysis. It would be inappropriate to infer that such an analysis was performed.

How should adverse-event counts be read?

Adverse-event counts describe the reported experience in the study group. They are not, by themselves, estimates of excess risk attributable to a device. A causal safety comparison needs an appropriate comparator and clear definitions of how events are collected, classified, and attributed. Event counts can also differ from counts of participants: one participant may experience more than one event, and an event term may occur more than once. The registry entries do not specify whether listed term percentages represent participants or event episodes, so they should be read as the registry’s reported term frequencies rather than converted into other measures.

Over-dispersion is a general concern when event counts vary more than a simple statistical model expects. If a model assumes that events occur with a particular degree of regularity but the real data are more variable, standard errors and intervals may be misleading. The registry record does not describe a count model or report repeated-event analysis, so there is no basis to say whether over-dispersion was assessed. For the participant-level binary primary endpoint, the more immediate requirements are a clear denominator, outcome ascertainment, and a stated method for handling missing observations.

What can planning calculations tell readers?

Sample-size calculations are planning illustrations, not observed results and not evidence that a study had a particular probability of success. The assumptions described for planning illustrations include a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. Those assumptions do not match the described single-group design without a comparator. The registry record does not report the study’s own sample-size justification, and no numerical planning estimate is available in the registry record. Such illustrations cannot replace a reported outcome analysis.

In general, a statistical test addresses whether data are compatible with a specified null hypothesis under its assumptions. A p-value does not measure the size or clinical importance of an effect, and it does not establish that a treatment works or does not work. No primary-outcome test result is reported in the registry record. Accordingly, there is no reported p-value to interpret, and no inferential conclusion should be imputed from the enrollment count or adverse-event figures.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("InnAVasc AVG Treatment")
n      <- c(26)
events <- c(7)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  InnAVasc AVG Treatment  26  7  26.9  11.6  47.8  13.7  46.1  13.8  46.3

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures, but the analysis details for the additional measure are not reported in the registry record. It does not state which outcomes were designated primary in a protocol version, whether there were additional planned comparisons, or how multiplicity was addressed. When several outcomes or tests are considered, the chance of at least one apparently unusual result can increase; methods for controlling that risk depend on the analysis plan. No such plan is reported, so the handling of multiplicity cannot be assessed.

Missing-data methods are also not reported. For the primary endpoint, interpretation requires knowing how many participants had an assessment at 6 months, whether any participants withdrew or were lost to follow-up, and how those without an observed endpoint were classified or handled. The enrollment figure alone does not establish the number with complete endpoint data. The registry record does not report an analysis population, a missing-data assumption, or sensitivity analyses.

The record does not describe whether analyses followed an intention-to-treat principle, included only participants who received the implant, or used another population definition. In a single-group device study, the distinction can affect the estimand: an analysis of everyone enrolled and one limited to participants who received or completed treatment may answer different questions. These definitions and their implications are not reported in the registry record.

Because the outcome result, analysis population, and missing-data handling are absent, readers cannot judge whether the reported endpoint—if analyzed—represents all enrolled participants or a selected subset. These are reporting limitations, not evidence that missing data or multiplicity necessarily biased the results.

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: infection of av graft (11.5%), bacteremia (11.5%), hematoma (3.8%), cerebral infraction with left hemiparesis (3.8%), post thrombectomy hematoma (3.8%).

The registry lists 12 participants with serious adverse events among 26 at risk in the InnAVasc treatment group. It lists other adverse events for 24 among 26 at risk, and reports 3 deaths. These are descriptive counts for the study group, not comparisons with an untreated or alternative-device group. They cannot establish how much risk is attributable to the graft, the procedure, the underlying condition, or other causes.

The serious adverse-event terms listed include Infection of AV Graft and Bacteremia, each at 11.5%, as well as Hematoma, Cerebral Infraction with Left Hemiparesis, Post Thrombectomy Hematoma, and Endocarditis, each at 3.8%. The registry record does not report the timing of these events, whether terms could overlap within participants, or whether the percentages refer to participants or event episodes. They should therefore be understood as reported term frequencies, not added together or treated as mutually exclusive categories.

The death count is stated separately. The record does not explain whether deaths were considered serious adverse events, whether they were related to the device or procedure, or when they occurred. It also does not provide comparative safety estimates or detailed event narratives. The counts are useful context about what was recorded, but they do not establish causality or permit a comparative safety conclusion.

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

The study record matters as a description of a device evaluation focused on hemodialysis access and a defined six-month secondary-patency outcome. The outcome definition includes graft abandonment and interventions intended to restore patency, making clear that the endpoint reflects more than a single observation of graft status. The record also reports adverse-event counts that provide descriptive safety context.

However, the registry entry does not report the primary endpoint count or an analysis of that endpoint. Readers therefore cannot determine from this record how many participants met the secondary-patency definition, how precisely the outcome was estimated, or whether follow-up was complete. The absence of a reported result is not equivalent to a poor result, a favorable result, or evidence that no analysis occurred outside the registry record.

The single-group design is another important boundary. Without a concurrent comparator, observed outcomes cannot establish how the graft compares with another access device or with standard care. The background statement that implantation and use are similar to other standard grafts does not supply comparative outcome data. Nor does the registry record provide a basis for attributing adverse events or deaths to the graft.

The status is terminated, but the reason for termination is not reported in the registry record. Termination alone does not reveal whether the decision was driven by safety, recruitment, feasibility, funding, or another issue. Similarly, enrollment and study dates do not establish that every participant completed follow-up.

The defensible interpretation is limited: the registry describes the intended population, intervention, single-group design, endpoint definition, and adverse-event counts, while leaving key outcome and analysis details unreported. It supports neither a claim that the graft works nor a claim that it does not work. A complete clinical assessment would require reported endpoint results, follow-up and missing-data details, and appropriately interpreted evidence beyond this single-group record.

14. Why This Trial Matters Statistically

This trial is statistically instructive because it separates an outcome definition from an outcome result. A registry can specify exactly what an endpoint means—in this case, secondary patency at 6 months—without reporting how many participants met it. Statistical interpretation requires both the definition and the observed data, along with enough information to understand the denominator and uncertainty.

The single-group structure also clarifies the difference between describing an outcome and estimating a treatment effect. Counts in one treated group can describe what was recorded among those participants. They cannot by themselves show what would have happened under another graft or access strategy. That distinction is central when interpreting device studies and when considering whether findings support comparative claims.

The adverse-event figures illustrate a related issue: descriptive safety counts are not automatically causal estimates. Without a comparison group, event attribution and detailed timing, the reported counts provide context but do not quantify an excess risk due to the device. Event terms may also overlap, so term frequencies should not be combined as if they represented separate groups of people.

Finally, the termination status and absence of reported analyses highlight the importance of transparent reporting. Readers need to know whether the primary endpoint was assessed, who was included, how missing observations were handled, and what uncertainty surrounds the estimate. Those details are not reported in the registry record. The appropriate statistical conclusion is therefore not a verdict on the device, but recognition of what the record describes and what it leaves unresolved.

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 is that the registry record does not report the primary endpoint result. Although secondary patency at 6 months is defined, there is no reported count of participants meeting the definition, no estimate of uncertainty, and no description of endpoint completeness. This prevents assessment of the primary outcome.

The single-group design limits comparative interpretation. There is no concurrent control arm, and allocation is listed as NA. Outcomes cannot establish a relative benefit or harm versus another access strategy. The registry’s description of standard graft use is not comparative evidence.

The record reports enrollment of 26, serious adverse events among 12 participants at risk of 26, other adverse events among 24 at risk of 26, and 3 deaths. It does not report event timing, attribution, narratives, or the relationship between deaths and adverse-event categories. The listed event-term percentages do not clarify whether terms overlap within participants or whether they refer to participants or event episodes.

Important design and analysis details are not reported in the registry record, including eligibility criteria beyond the stated clinical population, the reason for termination, the study’s own sample-size justification, the analysis population, missing-data procedures, and any interim analyses. The record also does not state whether all enrolled participants received the implant or completed the 6-month assessment. These gaps limit judgments about selection, follow-up, precision, and completeness. They do not, on their own, establish that the results are biased, but they constrain what can responsibly be concluded from the registry entry.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Evaluating the Safety and Effectiveness of the InnAVasc Graft for Dialysis Access in Patients With Kidney Failure — NCT03645681.
• Registry record last updated 2025-05-09; status last verified 2024-05.
• Results first posted 2023-06-15.
• 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

The registry describes a terminated, single-group study of the InnAVasc arteriovenous graft for hemodialysis access, sponsored by W.L.Gore & Associates. Enrollment was 26. The study began on 2019-01-02, with primary completion listed as 2019-09-28; allocation is NA and masking is none.

The primary outcome is secondary patency at 6 months, defined as being free from graft abandonment or an intervention intended to reestablish patency. The registry record does not report the primary outcome result or its analysis. It reports serious adverse events for 12 participants among 26 at risk, other adverse events for 24 among 26 at risk, and 3 deaths. The reason for termination, analysis population, missing-data handling, and comparative outcomes are not reported in the registry record.