Study of the Large Diameter GORE EXCLUDER® AAA Endoprosthesis in Abdominal Aneurysms: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of the Large Diameter GORE EXCLUDER® AAA Endoprosthesis in Abdominal Aneurysms (NCT00615069), a na phase 2 study. The primary outcome is Time to First Major Adverse Event Experienced by Subjects From the Time of Treatment Through 1 Year.

2. Clinical Question

3. Trial Design

This completed Phase 2 study evaluated the 31 mm GORE EXCLUDER® AAA Endoprosthesis in the primary treatment of infrarenal abdominal aortic aneurysms. The registry record identifies W.L.Gore & Associates as the sponsor. The study started in 2006-05, and primary completion was recorded in 2008-03.

The design is listed as single group, with allocation marked NA and masking listed as none. The intervention description specifies implantation of the 31 mm device. The record does not describe a concurrent control arm, random assignment, or blinding. Consequently, the design is not a randomized comparison, and it cannot directly estimate a difference between device treatment and a control treatment.

Enrollment is listed as 35. That is the registry enrollment figure; it should not be confused with an outcome-specific analysis population. The number included in the primary endpoint analysis, and any reasons for differences between enrollment and analysis, are not reported in the registry record.

The registry lists the study status as completed. Completion status describes the study’s recorded administrative status; it does not by itself establish that every planned analysis is reported. The record names a primary endpoint and a secondary safety outcome, but its numerical primary endpoint result, analysis details, and results for the secondary outcome are not reported in 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.

Overall Study

Reasons for not completing this period:

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 Time to First Major Adverse Event Experienced by Subjects From the Time of Treatment Through 1 Year, measured over Treatment through 1 year post-procedure (365 days).

The primary endpoint is titled “Time to First Major Adverse Event Experienced by Subjects From the Time of Treatment Through 1 Year.” It measures elapsed time from treatment to the first major adverse event, with the observation period described as treatment through 1 year post-procedure (365 days). The listed unit is days. The endpoint is summarized as a mean, with standard error as the stated measure of dispersion.

Time to first event is used to describe when an event first occurs, rather than simply whether any event occurred during follow-up. A mean expresses the average event time under the analysis approach; the standard error describes the precision of that estimated mean, not the spread of individual event times. These are general interpretations of the statistical measures.

The registry record does not report the mean, its standard error, the number of subjects contributing to the endpoint analysis, or details of how subjects without a recorded event were handled. It also does not report a numerical confidence interval or other result for this endpoint. Without those details, the endpoint definition alone cannot establish the observed timing of events or the precision of an estimated mean.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a continuous measure summarized by a mean, according to the registry record. In general, a mean is the arithmetic average of the values included in an analysis. For a time-to-first-event endpoint, those values represent elapsed times under the study’s analysis rules. The record identifies days as the unit and describes follow-up through 1 year post-procedure (365 days), but does not explain the precise calculation or handling of subjects who had no event during the observation period.

The listed dispersion measure is the standard error. In general, a standard error describes the precision of an estimated statistic, such as a mean, rather than how widely individual observations vary. A smaller standard error, considered in relation to the estimate and the analysis assumptions, indicates a more precise estimate. It is not a substitute for reporting the individual-level spread of event times. The numerical mean and standard error are not reported in the registry record, so precision cannot be assessed from this endpoint entry.

Time-to-event data often raise questions about censoring: a subject may have no event recorded before follow-up ends, or the timing of an event may be unavailable. In general, censoring methods account for incomplete observation without treating every subject as if the event happened at the last observed time. The registry record does not report whether censoring occurred, what method was used, or how it affected the mean time-to-event summary. It would be inappropriate to infer an analysis method from the endpoint title alone.

For any mean, the distribution of observations can matter. In general, a few unusually long or short times may influence the mean, and the mean may not describe a typical subject when values are strongly skewed. A confidence interval can show a range of values compatible with the data and the statistical model, expressing uncertainty in an estimate. The registry record does not report a confidence interval, a distributional assessment, or the method used to estimate uncertainty.

The study design is single group, with no randomized control comparison recorded. In general, estimates from a single group describe outcomes observed in that group; without a concurrent comparator, they do not isolate how outcomes would differ under another treatment or under no intervention. This design feature limits causal comparisons regardless of how precisely a within-group statistic is estimated.

The record also describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The stated effect to detect is a fraction of the observed effect. Such calculations are planning illustrations, not observed power and not evidence that the study was designed with those assumptions. The record does not report the trial’s own sample-size justification or design assumptions. Since the study itself is single group, the equal-allocation two-arm setup in the illustration should be understood as a hypothetical planning scenario, not as the study’s actual allocation.

In general, a significance level sets a decision threshold for a specified statistical test; it does not measure the probability that a hypothesis is true. A normal approximation uses a reference distribution to estimate uncertainty or calculate a planning quantity. Whether either approach is suitable depends on the endpoint, data, and analysis design. The registry record does not report the exact test, model, or assumptions used for the primary endpoint analysis, so those methods cannot be attributed to the trial.

Over-dispersion is a general concern when data vary more than a chosen model expects. If a model assumes less variability than is present, uncertainty can be understated and inferential results can become too optimistic. The registry record does not state that an over-dispersion model was used or that over-dispersion was assessed. It also does not report model diagnostics. No conclusion about this issue can be drawn from the endpoint definition.

The record lists two outcome measures and two analyses, but it does not give enough detail to identify all analysis procedures or relate each analysis to an outcome. It does not report whether analyses were adjusted, whether subgroups were considered, or whether any interim analyses took place. These details are not reported in the registry record and should not be inferred from the listed analysis count.

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("31 mm GORE EXCLUDER® Test Subjects")
n   <- c(35)
m   <- c(84)
sp  <- c(24.2)
sd  <- sp * sqrt(n)      # standard errors converted to SDs
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  31 mm GORE EXCLUDER® Test Subjects  35  84.000  143.169  34.820  133.180

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures and two analyses. It does not report a multiplicity strategy, such as whether statistical tests were adjusted to account for evaluating more than one outcome or analysis. Without that information, the record does not establish how any nominal statistical evidence would be interpreted across the listed outcomes. No primary endpoint numerical result or secondary outcome result is reported, so no multiplicity-adjusted or unadjusted inference can be described.

The primary endpoint has a defined observation period, but missing-data handling and the endpoint analysis population are not reported in the registry record. The entry does not explain whether all enrolled subjects contributed to the primary endpoint, how incomplete follow-up was treated, or how a subject without a recorded event was handled. Enrollment of 35 should not be treated as proof that all 35 contributed to every analysis.

The safety summary lists 35 subjects at risk for serious adverse events and 35 at risk for other adverse events, alongside the affected-subject counts. The record does not provide further detail about missing safety observations or the rules used to classify and count events. It also does not report an analysis population definition, protocol deviations, or exclusions. These omissions limit the ability to assess whether missingness or population selection could affect the reported safety summaries.

12. Safety Results

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

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: cardiac (20.0%), bowel (20.0%), other (20.0%), neurologic (20.0%), pulmonary (17.1%).

The registry record lists 24 subjects with one or more serious adverse events among 35 subjects at risk. It separately lists 33 subjects with one or more other adverse events among 35 subjects at risk. These are counts for the single study group, not comparisons between treatments. The record does not report a numerical count for deaths; deaths are listed as null, which means that death information is not reported in the registry record, not that no deaths occurred.

The serious adverse event terms listed are Cardiac, 20.0%; Bowel, 20.0%; Other, 20.0%; Neurologic, 20.0%; Pulmonary, 17.1%; and Wound, 11.4%. The registry record does not report the denominator for these percentages or whether the categories overlap. They should not be added together or interpreted as distinct, mutually exclusive subject groups. They also do not replace the overall count of subjects with one or more serious adverse events.

The secondary outcome names Type I Endoleak, Device Migration, and Major Procedural Bleeding Complications, but the associated result is not reported in the registry record. These safety data are descriptive and do not establish a comparative risk.

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

The record establishes that a completed Phase 2, single-group study evaluated implantation of the 31 mm GORE EXCLUDER® AAA Endoprosthesis for primary treatment of infrarenal abdominal aortic aneurysms. It defines time to first major adverse event through 1 year post-procedure (365 days) as the primary endpoint and specifies a mean with standard error. Those design and endpoint details identify what the study set out to describe.

The registry record does not report the numerical primary endpoint estimate, its standard error, or the result for the named secondary outcome. As a result, the posted information does not show the observed mean time to first major adverse event or its statistical precision. Missing numerical results should not be interpreted as zero events, no adverse events, or evidence that the device did or did not affect outcomes.

The safety entries report subjects with one or more events within the study group. Such counts provide a descriptive account of what was recorded, but they do not estimate a difference from another treatment. Because the study is single group and no control group is described, its design does not support a direct randomized comparison. Differences from other studies, if considered, could also reflect differences in populations, follow-up, event definitions, or other methods; those cross-study comparisons are not provided in the registry record.

In general, efficacy and safety interpretations depend on the outcome definitions, analysis methods, completeness of follow-up, and uncertainty around estimates. Here, important details of those analyses are not reported in the registry record. The registry entries therefore support a description of the study design and the listed safety counts, but not a conclusion about comparative effects or a quantified primary endpoint result.

14. Why This Trial Matters Statistically

This trial is statistically notable for the contrast between a clearly specified primary endpoint and the limited numerical results documented in the registry record. The endpoint is a mean time to first major adverse event, in days, over treatment through 1 year post-procedure (365 days). Naming an endpoint and its summary measure is useful, but interpretation also requires the estimate, its uncertainty, and enough analysis detail to understand how observed times were handled.

The single-group design is important when reading any reported outcome. A within-group safety count can describe the experience recorded in the study, but a treatment contrast requires a comparator. The record lists no separate control group and identifies the study model as single group. That distinction prevents descriptive event counts from being mistaken for comparative treatment effects.

The record also illustrates why safety summaries need context. It reports subjects with one or more serious and other adverse events, while listing several serious adverse event terms as percentages. The denominator and overlap of those terms are not reported in the registry record. In general, clear denominators and event-counting rules help readers understand whether percentages describe subjects, events, or another unit.

Finally, the planning illustration is not the same as the trial’s documented design justification. It uses an assumed two-arm planning framework, whereas the study is recorded as single group. Keeping planning calculations separate from observed analyses avoids treating hypothetical sample-size scenarios as trial outcomes or as observed power. The record does not report the trial’s own sample-size justification.

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 endpoint result is not reported in the registry record. The mean time to first major adverse event and its standard error are absent, as are a confidence interval and the number included in that endpoint analysis. The record also does not describe how subjects without an observed event or with incomplete follow-up were handled. These omissions prevent assessment of the primary estimate and its precision.

The single-group design has no concurrent comparison group recorded. Consequently, the safety counts cannot be interpreted as a comparative effect, and the design does not provide a direct estimate of how outcomes would differ under another treatment. The record does not report the detailed eligibility criteria, baseline characteristics, or further information about the enrolled subjects that might help readers judge the applicability of the findings.

The safety information is incomplete for several interpretive purposes. The death entry is null, so death information is not reported in the registry record. For serious adverse event terms, the denominator and whether categories overlap are not stated. The result for the named secondary outcome is also not reported. Further details about adverse event definitions, collection, and analysis are not reported in the registry record.

Analysis methods, missing-data procedures, multiplicity handling, analysis populations, and the trial’s sample-size justification are not reported in the registry record. The listed planning assumptions are illustrative and do not fill those gaps. These limitations concern what can be concluded from the registry entry; they do not establish that unreported procedures or results were absent from other study materials.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study of the Large Diameter GORE EXCLUDER® AAA Endoprosthesis in Abdominal Aneurysms — NCT00615069.
• Registry record last updated 2015-04-14; status last verified 2015-03.
• Results first posted 2009-07-09.
• 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

This completed Phase 2 study evaluated the 31 mm GORE EXCLUDER® AAA Endoprosthesis for primary treatment of infrarenal abdominal aortic aneurysms. The registry record lists enrollment of 35, a single-group model, no masking, and allocation marked NA. The study started in 2006-05, with primary completion in 2008-03.

The primary endpoint was mean time to first major adverse event, measured in days through 1 year post-procedure (365 days), with standard error specified. The numerical result is not reported in the registry record. Safety entries list 24 of 35 subjects with one or more serious adverse events and 33 of 35 with one or more other adverse events. A numerical result for the secondary outcome is not reported. The absence of a control group means the record describes a single study group rather than a randomized treatment comparison.