The GORE® VIABAHN® FORTEGRA Venous Stent IVC Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The GORE® VIABAHN® FORTEGRA Venous Stent IVC Study (NCT05409976), a na na study. The primary outcome is Initial Subject Analysis Population: Percentage of Subjects With Freedom From the Composite Endpoint of Effectiveness and Safety Events.

2. Clinical Question

The study concerns adults with symptomatic inferior vena cava obstruction, with or without combined iliofemoral obstruction. The registry describes evaluation of the GORE® VIAFORT Vascular Stent, formerly known as the GORE® VIABAHN® FORTEGRA Venous Stent, in this population. The clinical question is whether participants meet a composite measure of effectiveness and safety during follow-up after treatment with the device.

This is a study of performance, safety, and efficacy in participants receiving the device, not a randomized estimate of how outcomes differ between treatments. The registry lists 136 as planned enrollment, while its primary endpoint description says 89 participants were treated and 79 were evaluable for that endpoint. Those figures describe different stages or populations in the record; the reason for the difference is not reported in the registry record.

3. Trial Design

The registry describes a prospective, multicenter, non-randomized, single-arm study sponsored by W.L.Gore & Associates. Its listed intervention is the GORE® VIAFORT Vascular Stent. The study is marked as having no masking, with allocation and phase listed as NA. These design features mean the listed study does not provide a randomized device-versus-control comparison.

The record lists enrollment of 136. The primary endpoint population description states that 89 participants were treated and that 79 were evaluable for the primary composite endpoint. It also states that the Per Protocol and Intent to Treat populations were identical. How participants were selected for the evaluable group, and why treated and evaluable counts differ, are not reported in the registry record.

The primary endpoint timeframe is 12 months, although several component events are assessed through 30 days. The registry also lists secondary outcomes concerning patency, clinically driven target lesion revascularization, device fracture, stent embolization, device- or procedure-related death, pulmonary embolism, and vascular injury. It records 19 outcome measures and 0 analyses.

The study began on 2022-10-25. The listed primary completion date is 2026-05-09, and the current status is active, not recruiting. The date and status describe the registry record, not a completed analysis. No numerical primary endpoint estimate is reported in the registry record, so the design and endpoint can be described but the planned outcome cannot be judged from the posted record.

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 Initial Subject Analysis Population reflects the initial 89 subjects treated, as well as 15 screen failures, for a total of 104 subjects. The Supplemental Global Analysis Population subjects represent an additional 32 subjects consented (including 23 treated subjects) as part of a Global Analysis Population of 136 subjects (112 treated).

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The Per Protocol population and the Intent to Treat population were identical in this study. Of the 89 treated subjects, 79 were evaluable for the primary composite endpoint.

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 Initial Subject Analysis Population: Percentage of Subjects With Freedom From the Composite Endpoint of Effectiveness and Safety Events, measured over 12 months.

The primary endpoint is the percentage of subjects free from a composite of effectiveness and safety events at 12 months. The composite includes loss of primary patency through 12-month follow-up and stent embolization through 12-month follow-up. It also includes device- or procedure-related death through 30 days, clinically significant pulmonary embolism confirmed via Computed Tomography Angiography through 30 days, device- or procedure-related vascular injury through 30 days requiring surgical or endovascular intervention, and device- or procedure-related major bleeding events through 30 days.

A composite endpoint combines several outcomes into a single summary measure. In general, this can capture more than one way a procedure or device may fall short of its intended performance or raise a safety concern. It can also make interpretation less straightforward: the composite percentage does not by itself show which component occurred, how often each component occurred, or whether the components have similar clinical importance. Component-level results are needed for that detail.

The registry identifies the endpoint population as 79 evaluable participants among 89 treated participants. It specifies a 90% confidence interval, but does not report the primary endpoint percentage or interval estimate. Consequently, the endpoint definition is available, while its observed result and precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a binary percentage endpoint: the proportion of participants meeting the definition of freedom from the composite event. The endpoint is evaluated at 12 months, with individual components having their own stated observation windows. The primary result and its confidence interval are not reported in the registry record, so the method can be explained conceptually but not checked against a numerical estimate.

What does a percentage endpoint represent?

In general, a percentage for a binary endpoint is a count of participants classified in a specified way divided by the relevant analysis population. The definition of the numerator and the population used as the denominator matter. Here, the record names 79 participants as evaluable for the primary composite endpoint and reports 89 treated participants. It does not state the numerator of participants free from the composite, so no percentage can be recovered from the registry description.

The endpoint combines the absence of specified events: loss of primary patency and stent embolization through 12-month follow-up, plus several safety events through 30 days. In general, a participant is classified according to whether the composite definition is met. A composite can provide a concise summary across multiple event types, but it can conceal variation among components. Without component-level primary endpoint counts, readers cannot identify which part of the composite contributed most to the result.

What does the confidence interval add?

The registry specifies a 90% confidence interval for the primary endpoint. In general, a confidence interval expresses the statistical uncertainty around an estimated quantity under the method used to calculate it. It is not a range of outcomes for individual participants, and it does not show whether the estimate is clinically important. Its width is influenced by the amount of information and by the variability of the data. Since neither the endpoint estimate nor interval limits are reported, the precision of the study's primary estimate cannot be evaluated.

The registry record does not report the interval construction method, the analysis procedure, or other details of the primary statistical plan. Those details should not be inferred from the endpoint type or the stated confidence level. The record also lists 0 analyses, so it does not present a corresponding numerical analysis result.

Why does the design affect interpretation?

In general, a single-group study estimates outcomes in the group receiving the intervention. It does not create a like-for-like untreated or alternative-treatment group through randomization. Consequently, an outcome percentage from such a study would be descriptive of the analyzed participants; it would not directly estimate a difference between treatment groups. The registry explicitly describes this study as prospective, multicenter, non-randomized, and single-arm.

Prospective follow-up means the study is described as following participants forward for assessment. Multicenter means it takes place across multiple centers. These features describe the study structure but do not, by themselves, establish how outcome assessment was conducted or how potential differences among centers were handled. Those analytic details are not reported in the registry record.

How should planning illustrations be understood?

General sample-size planning uses assumptions about the effect to detect, the significance level, allocation, and the statistical approximation. The planning description associated with this study states 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. It distinguishes total event counts for time-to-event planning from participants per arm for other planning settings.

These are planning assumptions, not observed trial results. They do not change the fact that the registered study is single-group, and they should not be read as evidence of a randomized comparison in the clinical study. Planning sample sizes are not observed power. The record does not report a numerical primary endpoint estimate from which to assess an observed result, nor does it report the study's own sample-size justification. No numerical planning estimate is stated in the registry record.

In general, over-dispersion is a concern when variation in outcomes is greater than a model assumes; ignoring it can make uncertainty appear smaller than it is. The registry information does not state that over-dispersion was assessed or that a particular model was used. It is therefore a general statistical consideration, not a description of the study's analysis.

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("Initial Subject Analysis Population")
n      <- c(79)
events <- c(59)
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  Initial Subject Analysis Population  79  59  74.7  63.6  83.8  64.1  83.0  64.1  83.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 19 outcome measures and 0 analyses. It describes one primary composite endpoint and a range of secondary outcomes, including patency, revascularization, device fracture, embolization, pulmonary embolism, vascular injury, and death. Testing or estimating many outcomes can raise multiplicity concerns. In general, multiplicity means that interpreting numerous statistical tests as if each were the only test can increase the chance of chance findings. The registry record does not report a multiplicity adjustment, a hierarchy for secondary outcomes, or an analysis plan that would clarify how multiple outcomes were to be interpreted.

The primary endpoint population description states that 89 participants were treated and 79 were evaluable. It also says the Per Protocol and Intent to Treat populations were identical. The reason that the evaluable count differs from the treated count is not reported in the registry record. The registry does not report how missing endpoint data were handled, whether participants with incomplete follow-up were included in any particular analysis, or how censoring was treated.

In general, missing data can affect an estimate if the participants without outcome information differ from those with complete information. The direction and size of any effect depend on circumstances that are not described. The difference between treated and evaluable counts should therefore be noted, but it is not a basis for calculating a missing-data rate or assuming why observations were unavailable.

Because the primary estimate is not reported, neither its sensitivity to analysis-population choices nor the influence of incomplete follow-up can be assessed from 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: thrombosis in device (8.7%), in-stent venous restenosis (6.7%), cardiac tamponade (3.1%), pericardial effusion (3.1%), gastrointestinal ulcer bleeding (3.1%).

The registry reports serious adverse-event information for two named populations. For the Initial Subject Analysis Population, 104 participants were at risk, 45 were affected by serious adverse events, 25 were affected by other adverse events, and 2 deaths were reported. For the Supplemental Global Analysis Population Subjects group, 32 participants were at risk, 6 were affected by serious adverse events, 0 were affected by other adverse events, and 0 deaths were reported. The record does not explain in detail how the two populations relate to each other, so their counts should not be combined.

The listed serious event terms include Thrombosis in device at 8.7%, In-stent venous restenosis at 6.7%, Cardiac tamponade at 3.1%, Pericardial effusion at 3.1%, Gastrointestinal ulcer bleeding at 3.1%, and Upper gastrointestinal bleeding at 3.1%. These percentages are registry-reported event-term figures. The record does not provide further detail about whether participants could contribute to more than one term or the denominator used for each percentage; the values should not be summed or treated as mutually exclusive categories.

In general, adverse-event counts describe events observed or recorded in a study population and do not alone establish causation. The registry labels deaths and other events in its safety data, but the listed figures should not be read as proof that the device or procedure caused them. The relationship between the serious-event populations and the primary endpoint population is not reported in the registry record.

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

The registry record defines a clinically focused study question: the percentage of treated participants free from a combination of patency failure and specified safety events. It also identifies the primary endpoint timeframe, the event windows, the treated and evaluable population counts, and a 90% confidence interval as the intended expression of uncertainty. These details make the endpoint's intended scope understandable.

However, the primary endpoint estimate and interval are not reported in the registry record. No statement about the observed frequency of freedom from the composite, or the precision of that frequency, can therefore be made. The study's stated purpose is to evaluate performance, safety, and efficacy; that purpose is not itself evidence of an outcome. The listed design and endpoint should not be mistaken for results.

If an outcome percentage were reported, it would describe the analyzed participants under the endpoint definition. In general, a single-group study cannot directly show how that percentage compares with what would have happened under another treatment or no treatment. Differences in participant characteristics, follow-up, and other influences cannot be separated through randomization in this design.

The reported serious adverse-event counts and terms offer safety information for the named registry populations, but they do not answer the primary endpoint question. They also do not identify causal relationships or explain how the two safety populations relate to the primary analysis group. Reading these figures alongside the design requires keeping the population and outcome definitions distinct.

The appropriate conclusion is limited: the record describes a prospective, multicenter, non-randomized, single-arm device study and specifies a composite primary endpoint, but does not report the primary result. The absence of that result is not evidence that the endpoint was met or not met; it means the registry record does not allow that judgment.

14. Why This Trial Matters Statistically

This study illustrates a central issue in clinical biostatistics: a clearly stated endpoint does not by itself convey the outcome. The registry defines a composite that includes both effectiveness and safety events, sets different observation windows for its components, identifies an evaluable population, and specifies a confidence interval level. Yet the primary percentage and interval are not reported in the registry record. Without the estimate, readers cannot assess either the observed outcome or its precision.

The single-group design also matters for statistical interpretation. It can describe outcomes among participants treated with a device, but it does not supply a randomized comparator for estimating a treatment difference. This distinction is important when reading claims framed around performance, safety, or efficacy: those broad aims must be interpreted in light of the design and the actual results available.

The record also highlights why analysis populations and missing data need transparent reporting. It identifies 89 treated participants and 79 evaluable for the primary endpoint, while saying the Per Protocol and Intent to Treat populations were identical. The reason for the count difference and the handling of incomplete outcome information are not reported. Those details are relevant to understanding which participants contribute to an estimate and how representative it may be.

Finally, the registry lists multiple secondary outcomes and separate serious adverse-event summaries. Statistical interpretation depends on knowing which outcomes were analyzed, how multiple findings were handled, and how safety populations were defined. The registry record does not report those analysis details. The study is therefore a useful example of the difference between a protocol-level question, a defined endpoint, and a reported statistical result.

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 principal limitation for statistical interpretation is that the numerical primary endpoint result is not reported in the registry record. Although the endpoint definition and 90% confidence interval level are specified, the estimate and interval limits are absent. The observed frequency and precision of the primary outcome cannot be evaluated.

The study is non-randomized and single-group. It therefore has no concurrent randomized comparison in the registry description, limiting interpretation to outcomes in the treated study population rather than a direct estimate of relative effect. No control group outcome is reported.

The record lists 136 as enrollment, 89 treated participants, and 79 evaluable participants for the primary endpoint. It states that the Per Protocol and Intent to Treat populations were identical, but does not explain the difference between treated and evaluable counts or report the handling of missing endpoint information. That restricts assessment of analysis-population selection and potential missing-data effects.

The registry lists 19 outcome measures and 0 analyses. It does not report a statistical analysis plan, multiplicity approach, interim analysis information, or sample-size justification. These items should not be inferred. The serious adverse-event summaries use two named populations, but the record does not explain their relationship in detail. The listed event terms also do not, by themselves, establish causation.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The GORE® VIABAHN® FORTEGRA Venous Stent IVC Study — NCT05409976.
• Registry record last updated 2026-08-27; status last verified 2026-08.
• Results first posted 2026-04-29.
• 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

NCT05409976 is a prospective, multicenter, non-randomized, single-group study of the GORE® VIAFORT Vascular Stent for adults with symptomatic inferior vena cava obstruction, with or without combined iliofemoral obstruction. The record lists enrollment of 136, a study start date of 2022-10-25, a primary completion date of 2026-05-09, and status active, not recruiting.

The primary endpoint is the percentage of participants free from a composite of effectiveness and safety events at 12 months. The record says 89 participants were treated and 79 were evaluable; it specifies a 90% confidence interval but does not report the primary estimate or interval. Serious adverse-event counts and selected event-term percentages are reported for two named populations. The registry lists 19 outcome measures and 0 analyses, and does not report the analysis details needed to assess the primary result.