Endovascular Exclusion of TAAA/AAA Utilizing Fenestrated/Branched Stent Grafts: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Endovascular Exclusion of TAAA/AAA Utilizing Fenestrated/Branched Stent Grafts (NCT00583050), a na na study. The primary outcome is Freedom From Aneurysm Rupture.

2. Clinical Question

In statistical terms, the record poses a question about the occurrence of a defined event after endovascular repair in a treated group. Without a comparator, the study can describe outcomes among participants represented in that group, but the design does not directly estimate how those outcomes differ from a separate control group. The available record also does not give enough detail to assess how participants were selected, how the outcome was assessed in practice, or how follow-up was completed.

3. Trial Design

This is a completed, single-group device study sponsored by The Cleveland Clinic. The registry lists an enrollment of 1366 and an intervention called Endovascular Aneurysm Repair, described as repair of thoracoabdominal or abdominal aortic aneurysms with fenestrated or branched stent-grafts. The listed conditions are thoracoabdominal aneurysm and abdominal aortic aneurysm.

The study start is recorded as 2001-02 and primary completion as 2019-12-31. Its status is completed. The phase is listed as NA, which is consistent with the record identifying a device intervention rather than a drug phase. Masking is listed as none, and allocation is NA. The registry identifies the model as single-group.

These design features matter when interpreting any outcome. A single-group study can report the frequency of an event among participants who received the intervention, but there is no concurrent control arm in this record to support a direct treatment contrast. Differences from historical experience would require a separately specified and suitable comparison; none is described in the registry record. The listed intervention and outcome also do not establish that every participant had the same anatomy, procedure details, or follow-up duration.

The registry records one outcome measure and zero analyses. It does not report the statistical analysis plan, the planned sample-size rationale, eligibility criteria, the number of participants actually assessed for the primary outcome, or the approach to follow-up. Those omissions prevent a fuller assessment of how the study was planned and how its outcomes were evaluated. The design information supports describing the study structure, but not reconstructing unreported protocol decisions.

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

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 Freedom From Aneurysm Rupture, measured over 2 years.

The primary endpoint is titled “Freedom From Aneurysm Rupture,” with the unit specified as participants and the parameter described as a count of participants. Its timeframe is two years. The operational description is absence of blood extravasation outside of the aneurysm sac demonstrated by CT scan. In plain terms, the outcome concerns whether imaging indicates that blood has escaped beyond the aneurysm sac during the stated assessment period.

As a general statistical concept, a defined endpoint gives investigators a consistent outcome to record across participants. A clinically important event can be represented as a binary outcome: a participant either meets the event definition or does not, subject to the available assessment and follow-up. Clear definitions help distinguish the endpoint from related events that may be recorded elsewhere, including adverse-event terms that might use different criteria or observation periods.

The registry record does not report the number of participants meeting the freedom-from-rupture definition, the number with rupture, or the number with an available CT assessment at two years. It also does not report how deaths, missing scans, or incomplete follow-up were handled in determining this endpoint. Therefore, the endpoint definition and intended timeframe can be described, but the observed primary result and its precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods determine how recorded observations are converted into estimates and how uncertainty is represented. The registry record identifies a binary primary outcome measured as a count of participants, but does not report a primary-outcome analysis. It lists zero analyses. Thus, statistical concepts can clarify what an analysis could mean in general, while the actual analysis choices and results remain not reported in the registry record.

What does a binary outcome represent?

As a general concept, a binary outcome classifies each participant according to whether a defined event or condition is present. For this study, the endpoint is framed as freedom from aneurysm rupture according to the stated CT-based definition and two-year timeframe. A complete analysis would need to define how participants with no recorded assessment, incomplete follow-up, or death are classified. Those rules are not reported in the registry record. The endpoint wording alone does not reveal the handling of such cases.

A count is the number of participants assigned to an outcome category. A count is not, by itself, a percentage, risk estimate, or comparison. Interpreting a count requires knowing the relevant denominator and which participants contributed outcome data. Although enrollment is listed as 1366, the number assessed for the primary endpoint at two years is not reported in the registry record. It would therefore be inappropriate to assume that the enrolled group and the analyzed endpoint population are identical.

What would uncertainty describe?

As a general explanation, a confidence interval communicates uncertainty around an estimated quantity. Its width depends on factors such as the amount of information available and the variability represented by the data, as well as the analysis method. A confidence interval does not make a study randomized, remove bias, or guarantee that the true value lies within the interval. No primary-outcome estimate or confidence interval is reported in the registry record, so the precision of the primary result cannot be evaluated.

Statistical significance is also not a substitute for effect size or precision. A test result, if reported, would depend on its null hypothesis, model, and assumptions. The registry record does not report a hypothesis test or p-value for the primary outcome. It would be misleading to infer a test result from the enrollment count or from the adverse-event entries.

Why does the single-group design matter?

In a single-group design, a descriptive outcome can show what was recorded among participants in that group. It does not directly estimate a contrast with a control group because no comparator is listed. General statistical adjustment cannot create the missing concurrent comparison or guarantee that unmeasured differences have been addressed. A causal interpretation would need a design and analysis that support it, and those details are not reported in the registry record.

Observed outcomes in a treated group may reflect more than the intervention. Participant selection, baseline health, anatomy, clinical decisions, changes in care over time, and the completeness of outcome ascertainment can all affect what is recorded. These are general considerations for interpreting nonrandomized single-group evidence, not claims that any particular factor affected this study.

How should the adverse-event counts be understood?

The registry lists serious adverse events and other adverse events separately, each with 1366 at risk. These are counts in the safety listing, not estimates from an adjusted model. The record does not explain whether participants could appear in both categories, how events were classified, the observation window, or whether the entries were judged related to the device or procedure. The listed leading serious adverse-event term, Aneurysm Rupture at 1.6%, should be read as an adverse-event entry rather than assumed to be the primary endpoint result.

As a general concept, over-dispersion matters when a statistical model assumes that observations vary less than they do in the data. If present, over-dispersion can make standard errors too small and uncertainty appear narrower than justified. The registry record does not report a model for the primary outcome, so there is no basis to assess whether over-dispersion was considered or relevant to an analysis.

What does the record say about planning?

Sample-size planning is a prospective exercise based on an intended outcome, effect size, error rate, allocation, and analysis assumptions. A planning illustration is not a measure of what the study achieved and is not observed power. The registry record does not report the study's own sample-size justification. It also does not report a planned primary-outcome effect or a statistical analysis plan. Consequently, no conclusion about the adequacy of the planned enrollment or the power of the trial can be drawn from the record.

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("Endovascular Aneurysm Repair")
n      <- c(1366)
events <- c(22)
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  Endovascular Aneurysm Repair  1366  22  1.6  1.0  2.4  1.1  2.4  1.1  2.4

11. Multiplicity, Missing Data and Analysis Populations

Multiplicity concerns arise when a study makes several statistical comparisons or evaluates several outcomes in ways that can increase the chance of a false-positive finding. The registry lists one outcome measure and zero analyses. It does not report multiple primary outcomes or statistical tests, but the available record is not a complete analysis plan. Any multiplicity strategy, such as a hierarchy of outcomes or adjustment of significance thresholds, is not reported in the registry record.

Missing data are also important for a time-specific endpoint. The primary outcome is defined at two years using CT evidence, but the record does not state how many participants had an evaluable scan, how many were lost to follow-up, or how incomplete observation was handled. It does not describe whether participants with missing imaging were excluded, treated as having an event, or addressed through another method. Those choices can affect an estimated event frequency and its interpretation. The registry record does not report them.

The analysis population is not described. Enrollment is listed as 1366, but the record does not say whether every enrolled participant received the device procedure, contributed safety information, or was included in any primary-outcome analysis. Because zero analyses are listed and no primary result is posted, there is no basis to identify an intention-to-treat, treated, per-protocol, or other analysis population. These are not interchangeable populations; their definitions should be specified before interpreting an estimate.

These gaps do not establish that the study failed to conduct analyses or collect follow-up information. They mean that those details are not reported in the registry record. Without an endpoint denominator, missing-data rules, and analysis-population definition, readers cannot assess the representativeness of the primary-outcome observations or how sensitive any result might be to incomplete follow-up.

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: aneurysm rupture (1.6%).

The safety listing records 22 serious adverse events among 1366 at risk and 68 other adverse events among 1366 at risk in the Endovascular Aneurysm Repair group. It also records 775 deaths. The listed leading serious adverse-event term is Aneurysm Rupture at 1.6%. These entries should be read as registry figures, not as a comparative safety analysis.

The record does not provide the definitions used for serious and other adverse events, their observation period, event-level details, or whether events were considered related to the device or procedure. It also does not report whether an individual could contribute to both adverse-event categories. The counts therefore cannot be interpreted as mutually exclusive groups of participants unless the record establishes that, and it does not.

The primary endpoint is a separate CT-based measure of freedom from aneurysm rupture at two years. The adverse-event term Aneurysm Rupture may sound related, but the record does not establish that it uses the primary endpoint's definition or timeframe. The 1.6% entry should not be substituted for a primary-outcome result.

The 775 deaths are recorded without a cause or timing breakdown in the available record. They cannot be assumed to be treatment-related, nor can they be dismissed as unrelated. No comparison group is listed, so these figures do not support a comparative conclusion about safety. They describe what the registry lists, with important context unavailable.

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

The record establishes that a completed, single-group study evaluated endovascular aneurysm repair with fenestrated or branched stent-grafts in participants with thoracoabdominal or abdominal aortic aneurysms. It lists enrollment of 1366 and defines freedom from aneurysm rupture at two years as the primary outcome. It also lists adverse-event counts and deaths for the intervention group.

What the record does not establish is the observed primary-outcome result. There is no posted count for participants meeting the endpoint definition, no analysis estimate, and no reported uncertainty interval. The absence of these items means the primary outcome cannot be quantitatively interpreted from the registry record. It does not mean that no rupture occurred, that every participant was free from rupture, or that the endpoint was not assessed.

The single-group design also limits what any within-group result could establish. Without a comparator, the registry does not provide a direct estimate of the difference between the procedure and another approach. A count of events or participants in the treated group cannot by itself show that the intervention caused a particular outcome. Comparisons with other populations would require relevant methods and information not reported in the registry record.

The safety entries are descriptive and lack details about event definitions, timing, attribution, and overlap between categories. The death count has no accompanying cause or timing information in the record. These figures should not be converted into a claim of benefit or harm, or treated as an estimate of comparative risk.

In general, results are most interpretable when outcome definitions, denominators, follow-up completeness, analysis populations, and uncertainty are transparent. Several of these elements are not reported in the registry record. The responsible conclusion is therefore narrow: the registry documents the study design, intended primary endpoint, enrollment, and selected safety entries, but it does not report the primary result needed to quantify freedom from aneurysm rupture at two years.

14. Why This Trial Matters Statistically

This study is statistically notable for the contrast between a clearly named, time-specific primary outcome and the absence of a posted analysis for that outcome. The endpoint is defined as freedom from aneurysm rupture at two years, with a CT-based description, yet the record reports neither the number of participants meeting that definition nor an estimate of uncertainty. This illustrates why an endpoint definition and a result are different kinds of information: the definition explains what is intended to be measured, while the result shows what was observed.

The single-group design is another important feature. Describing outcomes after a procedure can be useful, but it does not supply the direct comparison that a controlled design would provide. The statistical question answered by a descriptive count is not the same as the comparative question of whether outcomes differ between approaches. Clear communication about that distinction helps prevent overinterpretation of findings from nonrandomized evidence.

The safety listing also demonstrates why endpoint labels and adverse-event terms should be interpreted in context. Aneurysm Rupture appears as a serious adverse-event term, while the primary endpoint is a two-year, CT-defined measure of freedom from rupture. The record does not establish that the definitions, timeframes, or participant accounting are identical. Treating similar wording as proof of identical measurement would go beyond the reported information.

Finally, the record leaves key elements of statistical evaluation undocumented, including the primary-outcome analysis, missing-data handling, and analysis population. These details shape the meaning and reliability of an estimate. Their absence does not prove that a particular method was or was not used; it limits what readers can verify from the registry record. The study is therefore a useful example of why design, outcome reporting, and analysis transparency must be considered together.

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 most consequential limitation for statistical interpretation is that the registry record does not report a result for the primary endpoint. The endpoint is specified, but there is no observed count, estimate, or uncertainty interval. This prevents assessment of the primary question as recorded.

The single-group design has no listed comparator, and allocation is NA. The study therefore cannot provide a direct, concurrent treatment contrast in the registry record. A descriptive outcome in this group would not, by itself, establish that the intervention caused the outcome. No adjustment strategy or comparative analysis is reported.

Important details about outcome ascertainment are also absent. The record does not report the number with evaluable CT scans at two years, completeness of follow-up, or the handling of missing assessments and deaths. It does not state the analysis population or provide eligibility criteria and baseline characteristics. These omissions constrain interpretation of who contributed information and how representative the observations might be.

The safety entries lack event definitions, timing, attribution, and detail about potential overlap between serious and other adverse events. The deaths are not described by cause or timing. The serious adverse-event term Aneurysm Rupture is not established as equivalent to the primary endpoint, so it cannot fill the gap in primary-outcome reporting.

Finally, the statistical analysis plan and the study's own sample-size justification are not reported in the registry record. The record lists zero analyses. This limits assessment of prespecification, model choice, precision, and the handling of multiple outcomes or incomplete data. These are limits on what can be concluded from the record, not evidence about what occurred outside it.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Endovascular Exclusion of TAAA/AAA Utilizing Fenestrated/Branched Stent Grafts — NCT00583050.
• Registry record last updated 2020-05-08; status last verified 2020-04.
• Results first posted 2020-05-08.
• 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 record identifies NCT00583050 as a completed, single-group device study sponsored by The Cleveland Clinic. It lists an enrollment of 1366, with thoracoabdominal aneurysm and abdominal aortic aneurysm as conditions. The intervention is endovascular aneurysm repair using fenestrated or branched stent-grafts.

The study start is listed as 2001-02, and primary completion as 2019-12-31. Allocation is NA and masking is none. The primary outcome is freedom from aneurysm rupture at two years, described as absence of blood extravasation outside the aneurysm sac demonstrated by CT scan. The primary-outcome result and analysis are not reported in the registry record.

The safety listing records 22 serious adverse events, 68 other adverse events, and 775 deaths, each with 1366 at risk; Aneurysm Rupture is listed at 1.6% among the leading serious adverse-event terms. The record does not provide the additional event context needed for causal or comparative interpretation. It lists one outcome measure and zero analyses.