Evaluation of FUSION™ Vascular Graft for Above Knee Targets: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of FUSION™ Vascular Graft for Above Knee Targets (NCT01601496), a na na study. The primary outcome is Participants With Primary Graft Patency at 12 Months.

2. Clinical Question

This is a descriptive question about outcomes observed in a group receiving the device, rather than a randomized estimate of the difference between treatment options. The registry lists secondary outcomes concerning secondary graft patency at 12 months; mean ankle-brachial index and Rutherford category at 30 days, 6 months and 12 months; and major adverse limb events and periprocedural death. Those outcomes broaden the planned description of graft performance and clinical events, but their numerical results are not reported in the registry record. The record lists 117 participants enrolled. That enrollment count should not be assumed to be the number included in every endpoint analysis: the primary analysis population is defined by availability of a documented failure or a 12-month patency assessment, and the number meeting that definition is not reported in the registry record.

3. Trial Design

This was a prospective, single-group post-market device study, according to its official title and registry description. The intervention was the FUSION Vascular Graft, and the arm description includes subjects who received the graft at the baseline implant procedure. The registry lists PAOD as the condition and describes the study purpose as evaluating safety and performance. The title identifies above-knee targets.

The registry records enrollment of 117 and status as terminated. The listed start date is 2009-10-26, and the primary completion date is 2013-07-24. The phase is recorded as NA. Allocation is also recorded as NA, masking as none, and the model as single group. No separate control arm is described, so the study design does not support a direct randomized comparison between the graft and another intervention.

The primary outcome is the number of participants with primary graft patency at 12 months. Patency was assessed by duplex ultrasound imaging, and the endpoint definition excludes a graft that required an intervention after implantation. The registry also lists secondary outcomes covering secondary graft patency, ankle-brachial index, Rutherford category, major adverse limb events and periprocedural death. The numerical results for these outcomes are not reported in the registry record.

The record does not report a sample-size justification, detailed statistical analysis plan, interim-analysis plan, or the reasons for termination. It also does not state how many enrolled participants completed follow-up or contributed data to each outcome. These omissions limit assessment of how the study was planned and how fully each endpoint was observed. The registry lists zero analysis entries; that does not establish whether analyses were conducted outside the registry 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: Patients were enrolled if they had peripheral artery occlusive disease (PAOD), signed informed consent forms, received subject numbers, and were screened for inclusion in the study. One subject failed to meet all eligibility criteria, prior to implantation of a FUSION vascular graft, and was not included in the efficacy or safety analyses.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Analysis limited to participants who were known primary patency failures (i.e. interventions were documented) or had a patency assessment at 12 months.

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.

Population: Patients with peripheral vascular disease who underwent femoral-to-above-knee popliteal bypass with a FUSION Vascular Graft.

6. Primary Endpoint

The registry lists the primary outcome as Participants With Primary Graft Patency at 12 Months, measured over 12 Months.

The primary endpoint is the count of participants with primary graft patency at 12 months. A graft qualifies as patent under the registry definition if it remains continuously patent from implantation, with uninterrupted blood flow and no intervening procedures. Patency was assessed using duplex ultrasound imaging. The endpoint is therefore a participant count based on a defined status at a specified follow-up time, not a measurement of the degree of blood flow or a comparison between groups.

Patency is used as a measure of graft performance: it records whether the implanted graft has remained open without an intervention that would interrupt the endpoint definition. The distinction between primary and secondary patency matters because the primary definition requires uninterrupted patency without interventions. The registry lists secondary graft patency as a separate outcome, but its detailed definition and result are not reported in the registry record.

The endpoint population is defined as participants known to have had a primary patency failure, where interventions were documented, or participants with a patency assessment at 12 months. This means the endpoint description does not establish that every enrolled participant was included in the primary analysis. The count of participants with patency, the number contributing to this endpoint, and any estimate of uncertainty are not reported in the registry record. Without those values, the endpoint definition can be described, but the observed level of patency and its precision cannot be assessed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods can help distinguish what an outcome measures from how confidently it has been estimated. In this study, the primary endpoint is a count of participants meeting a binary definition of primary graft patency at 12 months. Each participant either meets that definition or does not, based on continuous patency without intervention from implantation and assessment by duplex ultrasound imaging. The registry does not report the observed count, denominator, confidence interval or other uncertainty estimate, so the size and precision of the endpoint result cannot be evaluated from the registry record.

What does a participant count tell the reader?

A count is an absolute number of participants who meet an endpoint. It is not, by itself, a rate or a proportion. To interpret a count in relation to the participants assessed, the denominator and rules for inclusion must also be known. Here, the primary analysis population is described as participants with documented primary patency failures or a patency assessment at 12 months. The size of that population is not reported in the registry record. Enrollment of 117 should therefore not be substituted for an endpoint denominator.

In general, an interval estimate describes a range of values compatible with the data and the method used to calculate it. A narrower interval indicates greater precision under that method, while a wider interval indicates more uncertainty. The registry record does not report an interval for the primary endpoint. It is consequently not possible to characterize the precision of the 12-month patency result.

Why does the single-group design matter?

A single-group study can describe outcomes among participants receiving an intervention. It does not create a concurrent comparison group. Without such a group, differences that might have occurred under another treatment or without the device cannot be estimated directly from this design. This is a general limitation of interpretation, not a claim about whether the graft caused any specific event. The record lists no randomized comparison and describes one group receiving the FUSION Vascular Graft.

The absence of a comparator also means that the observed safety figures are not comparative risk estimates. They describe events recorded among participants in the study group; they do not show whether event frequency was higher or lower than it would have been with another device. The registry does not report event attribution or comparative safety analyses.

What can be inferred from the analysis entries?

The registry lists zero analysis entries. That indicates no analysis entries are reported in the registry record, but it does not establish that no statistical work was performed. The analysis methods, including any model, adjustment strategy, handling of censoring, or uncertainty calculations, are not reported in the registry record. No p-value or adjusted estimate is reported for the primary endpoint.

The sample-size assumptions associated with planning illustrations describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect set as a stated fraction of the observed effect. Those assumptions describe planning illustrations, not the design features of this single-group study. The record does not report the trial's own sample-size justification, and illustrations based on an observed effect are not observed power. No numerical illustration values are reported in the registry record.

How should the safety counts be read statistically?

Counts of participants affected by adverse events are descriptive. A person-level count is different from a count of all event episodes, because one participant can experience more than one event. The registry reports participant counts for serious and other adverse events, but does not explain event-level totals, overlap among categories, or attribution. The listed serious-event terms have percentages, but the registry record does not specify the denominator or fully describe how those terms were counted. They should be read as reported event descriptors, not as mutually exclusive groups or comparative estimates.

In general, over-dispersion matters when the observed variability in event counts is greater than a statistical model expects. A model that does not account for that extra variability may give uncertainty estimates that are too narrow. This is a general statistical consideration for count outcomes; the registry does not report a count model or indicate whether over-dispersion was assessed in this study.

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("FUSION Vascular Graft")
n      <- c(104)
events <- c(89)
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  FUSION Vascular Graft  104  89  85.6  77.3  91.7  77.6  91.1  77.5  91.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and several secondary outcomes: secondary graft patency at 12 months; mean ankle-brachial index at 30 days, 6 months and 12 months; Rutherford category at those same follow-up times; and major adverse limb events and periprocedural death. Testing or estimating several outcomes can raise multiplicity concerns. In general, multiplicity refers to the increased chance of a misleading positive finding when many statistical questions are evaluated. A prespecified hierarchy or adjustment can help address that concern, but the registry record does not report whether either was used.

The record does not provide an analysis plan describing how multiple outcomes or repeated follow-up times were handled. It does not report interim analyses, and the timing or rules for any such analyses are not reported in the registry record. The registry lists zero analysis entries; this does not establish whether outcome analyses were conducted elsewhere.

Missing outcome data also affect interpretation. The primary endpoint population includes participants with a documented primary patency failure or a 12-month patency assessment. The record does not report how many participants lacked an assessment, how missing observations were handled, or whether follow-up differed across participants. It also does not report the number contributing to each secondary outcome. Without these details, the extent and possible influence of missing data cannot be assessed.

General methods for missing data depend on why values are missing and on the assumptions used to address them. Those reasons and assumptions are not reported in the registry record. The participant count enrolled should not be treated as proof that all participants had outcome data. Nor does the absence of numerical endpoint results indicate that missingness was handled in any particular way.

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

Serious events with the highest arm-level rate: vascular graft occlusion (12.8%), wound infection (6.8%), haematoma (3.4%), seroma (2.6%), ileal stenosis (1.7%).

The registry reports 48 participants affected by serious adverse events, with 117 at risk, and 0 participants affected by other adverse events, also with 117 at risk. It separately lists 4 deaths. These figures describe the safety information entered in the registry; they do not by themselves establish whether events were caused by the graft or how deaths relate to the serious-event count.

The listed serious adverse event terms include vascular graft occlusion at 12.8%, wound infection at 6.8%, haematoma at 3.4%, seroma at 2.6%, ileal stenosis at 1.7%, and impaired healing at 1.7%. The registry record does not specify the denominator for these term percentages or whether a participant could appear under more than one term. These terms should not be assumed to represent mutually exclusive participant groups.

In general, a participant affected by a serious adverse event is not necessarily equivalent to a single event episode: one participant may have more than one event. The record does not report event-level totals, seriousness criteria, attribution, timing, or comparative safety data. The single-group design also means these counts cannot be compared directly with a control group in this study.

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

The record describes a study of the FUSION Vascular Graft in a single group of participants with PAOD and a primary question about primary graft patency at 12 months. It defines patency in concrete terms: uninterrupted patency from implantation, with no interventions, assessed by duplex ultrasound imaging. It also reports enrollment and a set of safety figures, including serious adverse events and deaths.

Those details do not establish the primary outcome result. The number of participants with primary patency, the denominator for that endpoint, and any estimate of uncertainty are not reported in the registry record. Secondary outcome results are also not reported. The available endpoint definition explains what was intended to be measured, but it cannot substitute for the observed result.

The study's single-group structure matters for claims about comparative effects. The registry does not describe a separate comparator or randomized allocation. Therefore, the listed observations cannot quantify how outcomes would differ under another graft or treatment. The adverse event counts also do not establish device causation; attribution is not reported in the registry record.

In general, statistical interpretation requires attention to both the estimated outcome and its uncertainty, as well as to who contributed data and how comparisons were made. In this record, the analysis population is described but its size is not reported. The record also does not report confidence intervals, p-values, a detailed statistical analysis plan, or how missing data were handled. These gaps limit conclusions about precision and analytic robustness.

The responsible reading is therefore descriptive and bounded: the registry documents a terminated, single-group post-market study with 117 enrolled participants, a defined 12-month patency endpoint, and reported safety counts. It does not report enough primary or secondary outcome results to judge the observed level of graft patency or its statistical precision. Neither unreported outcomes nor absence of registry analysis entries should be interpreted as evidence for a particular clinical conclusion.

14. Why This Trial Matters Statistically

This study illustrates why endpoint definitions and reported results are both necessary for statistical interpretation. The primary outcome is defined with specific clinical and procedural criteria: continued patency from implantation, no interventions, and assessment by duplex ultrasound at 12 months. That definition tells readers what the study intended to count. Without the observed count and the number of participants assessed, however, the endpoint cannot be summarized as an outcome estimate.

It also illustrates the distinction between a single-group description and a comparative treatment effect. A study can document outcomes among people receiving a device, but comparison with another option requires a comparator and an appropriate design. The registry lists one group and no randomized comparison. This means its reported observations answer a descriptive question rather than a direct question about relative outcomes.

The record further shows why enrollment, analysis population, and follow-up completion should not be treated as interchangeable. Although 117 participants were enrolled, the primary endpoint population is limited to people with documented failure or a 12-month patency assessment. The size of that population is not reported in the registry record. This distinction is important whenever outcome availability determines who contributes to an analysis.

Finally, safety counts and event-term percentages need context. Counts describe the events recorded, but do not on their own identify causation, overlap, or comparative risk. The registry does not provide those details. These are general statistical reading principles, and they are especially relevant when the public record contains endpoint definitions and safety summaries but not the full analysis results.

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 primary limitation for interpreting efficacy-related outcomes is that the registry record does not report the numerical result for primary graft patency at 12 months. It also does not report the denominator for the primary endpoint or an uncertainty estimate. Thus, neither the observed patency count nor its precision can be assessed.

The single-group design has no reported comparator, so the record cannot support a direct between-group estimate. The registry does not report randomization, and allocation is recorded as NA. The study is listed as terminated, but the reason for termination is not reported in the registry record.

The primary analysis population is restricted to participants with known failures or a patency assessment at 12 months. The number meeting this definition, the number with missing assessments, the completeness of follow-up, and the missing-data approach are not reported. Enrollment of 117 does not resolve these uncertainties.

The registry lists secondary outcomes but does not report their numerical results. It also does not report a detailed statistical plan, multiplicity procedures, interim-analysis details, or a sample-size justification. The analysis-entry count is zero, which describes the registry record and does not establish what analyses may have been conducted elsewhere.

For safety, the record gives participant counts, deaths, and percentages for selected serious adverse event terms, but does not report event attribution, timing, overlap, or the denominator underlying the term percentages. The clinical interpretation of the listed safety figures is therefore limited. The record also does not report additional eligibility, baseline, or follow-up details that would allow a fuller assessment of how representative the enrolled group was.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Evaluation of FUSION™ Vascular Graft for Above Knee Targets — NCT01601496.
• Registry record last updated 2020-10-14; status last verified 2020-10.
• Results first posted 2020-10-14.
• 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 post-market study of the FUSION Vascular Graft for above-knee targets in PAOD. It is listed as single group, with no masking, enrollment of 117, and status terminated. The listed start date is 2009-10-26, and the primary completion date is 2013-07-24.

The primary outcome is participants with primary graft patency at 12 months, defined as uninterrupted patency from implantation without interventions and assessed by duplex ultrasound. The count and analysis denominator are not reported in the registry record. Secondary outcomes cover patency, ankle-brachial index, Rutherford category, major adverse limb events and periprocedural death; their numerical results are not reported.

The safety record lists 48 participants affected by serious adverse events, 0 affected by other adverse events, and 4 deaths. No analysis entries are listed. The registry does not report a comparator, detailed statistical plan, missing-data handling, or the reason for termination.