Evaluation of the GORE® EXCLUDER® Thoracoabdominal Branch Endoprosthesis in the Treatment of Thoracoabdominal and Pararenal Aortic Aneurysms: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of the GORE® EXCLUDER® Thoracoabdominal Branch Endoprosthesis in the Treatment of Thoracoabdominal and Pararenal Aortic Aneurysms (NCT03728985), a non-randomized na study. The primary outcome is Percent of Subjects With Uncomplicated Technical Success and Freedom From Procedural Safety Composite Event.

2. Clinical Question

3. Trial Design

This is a prospective, non-randomized, multicenter study with two independent arms. The registry lists a parallel model, no masking, and allocation as non-randomized. Its phase is recorded as NA. W.L.Gore & Associates is the sponsor. The status is active, not recruiting. The recorded start date is 2019-06-17 and the primary completion date is 2023-01-04.

The primary study arm includes Crawford Type IV thoracoabdominal aortic aneurysms and pararenal aneurysms requiring only the TAMBE System. The registry describes this arm as n= 102 and says its analysis is hypothesis-driven. The secondary arm includes Crawford Type I-III thoracoabdominal aortic aneurysms requiring the TAMBE System and CTAG device or devices; its stated range is n= 20 - 100. Its analysis is described as non-hypothesis-driven. These arm descriptions indicate different clinical groups and device configurations, not a treatment group and a comparable control group.

The brief summary states a minimum of 122 implanted participants and a maximum of 202 implanted participants, with up to 65 additional participants implanted in a continued access phase under the primary arm only. The separate enrollment field records 102. These are different registry statements and should not be treated as interchangeable measures of enrollment or of the analyzed population. The record does not reconcile them.

The intervention is a device evaluation, rather than a randomized comparison of alternative treatments. No allocation procedure, masking process, or detailed recruitment approach is reported in the registry record. The primary endpoint is an early procedural composite, with its timeframe extending from the start of the index procedure to 59 days post procedure. The record lists 33 outcome measures and two analyses but does not provide a full statistical analysis plan.

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: Subjects went through Screening after Enrollment. Subjects available and eligible for Primary Arm were implanted.

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 Percent of Subjects With Uncomplicated Technical Success and Freedom From Procedural Safety Composite Event, measured over From start of Index Procedure to 59 Days Post Procedure.

The primary endpoint is the percent of participants with uncomplicated technical success and freedom from a procedural safety composite event. It combines successful access and delivery, successful and accurate deployment, and successful withdrawal during the index procedure with freedom from specified procedural safety events. The safety component includes stented segment aortic rupture, lesion-related mortality, permanent paraplegia, permanent paraparesis, new onset renal failure requiring dialysis, severe bowel ischemia, and disabling stroke. The registry defines the endpoint timeframe as from the start of the index procedure to 59 days post procedure, while describing the procedural safety events as occurring during 30 days of the index procedure.

A composite endpoint brings several clinically important events or technical requirements into a single outcome. In general, that can capture a broader view of procedural performance than a measure focused on a single event. It also means the composite result depends on all of its components: a reported composite alone would not establish how often each component occurred, or which component most influenced the overall result. Component-specific results would be needed to assess that pattern.

The endpoint is recorded as a participant count measure, with the stated result concept being a percent of participants. However, the primary endpoint result, its numerator and denominator, and any estimate of precision are not reported in the registry record. The definition therefore describes what was intended to be assessed, but does not establish the observed frequency of success or safety events.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a binary endpoint represent?

In general, a binary endpoint classifies each participant according to whether a defined event or composite occurred. For this trial, the primary endpoint is described as a percent of participants meeting a combined definition: technical success together with freedom from the procedural safety composite. A participant-level outcome can be summarized as a count and a proportion, but interpretation requires knowing the exact analysis population, the number with an evaluable outcome, and how missing endpoint information was handled. Those analysis details and the primary result are not reported in the registry record.

The composite definition combines procedural technical requirements with safety events. In general, combining components can make a broad outcome easier to summarize, but components can differ in severity and frequency. A composite estimate does not show whether its result is mainly driven by technical success or by any particular safety event. Component results and clear definitions of the analysis population help readers understand what the combined measure represents. Component-specific primary endpoint results are not reported in the registry record.

How should precision be judged?

In general, a confidence interval expresses uncertainty around an estimated effect or event frequency. Its width reflects how precisely the data estimate that quantity under the chosen statistical method. A narrow interval conveys greater precision than a wide interval, but neither an interval nor a point estimate alone resolves biases from study design. The registry record does not report a confidence interval for the primary endpoint, so the precision of that endpoint cannot be assessed from the recorded details.

For proportions, methods for calculating intervals can differ, especially when event counts are sparse or proportions are near a boundary. The registry record does not identify the interval method for the primary endpoint. It also does not report whether the endpoint was analyzed as a proportion, with a formal hypothesis test, or using another model. No method should be inferred from the endpoint label alone.

Why does the non-randomized design matter?

In general, random allocation helps balance measured and unmeasured participant characteristics between groups, on average. A non-randomized study does not have that protection. Differences between groups can reflect baseline characteristics, clinical selection, treatment configuration, or other factors as well as the intervention under study. Here the two arms are explicitly different: the primary arm concerns Crawford Type IV and pararenal aneurysms treated with the TAMBE System alone, whereas the secondary arm concerns Crawford Type I-III aneurysms treated with TAMBE and CTAG device or devices. This makes a direct arm-to-arm treatment contrast especially difficult to interpret as a causal comparison.

The record calls the arms independent and describes hypothesis-driven analysis for the primary arm and non-hypothesis-driven analysis for the secondary arm. It does not give the exact hypotheses, the estimand, adjustment variables, or the statistical model. An estimand is the precise quantity an analysis aims to estimate, including the population, outcome, and handling of events such as missing observations. Without that definition, the analysis target cannot be reconstructed from the arm descriptions.

What can sample-size planning illustrations tell readers?

In general, a sample-size calculation estimates how much information a future study might need under stated assumptions. The registry's planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect expressed as a fraction of the observed effect. The record characterizes these as planning illustrations computed from the observed effect, not as the trial's own design. They are not observed power, and they do not establish that the study was planned with those assumptions.

Sample-size illustrations depend on the assumed effect and analysis conditions. If the observed effect is imprecisely estimated, using it as a planning basis can make the illustration uncertain as well. A planning value is not a new trial result and should not be used as evidence that a study had a particular probability of detecting an effect after the fact. The record does not report numerical planning estimates in the registry record, nor does it report the original design's sample-size justification.

The record notes a normal approximation for planning. In general, approximations simplify calculations and may be less reliable when their conditions are not well met; whether that matters depends on the outcome, event frequency, and sample size. The available record does not provide enough detail to assess those conditions for a particular calculation. No additional calculation can be inferred from the assumptions alone.

How should adverse-event summaries be read?

In general, an adverse-event count is a descriptive summary, not automatically an estimate of treatment-caused harm. Interpretation depends on how events were defined, collected, timed, and adjudicated, along with the population under observation and the follow-up period. Serious adverse events and other adverse events may overlap, and a person may experience more than one event. The registry's figures are participant-based fields, but the record does not provide further detail on overlap, event recurrence, adjudication, or event-specific observation time.

A percentage attached to a listed safety term should be understood in the context of its denominator and collection rules. The available record lists percentages for the top serious terms but does not provide additional denominator or timing details for each term. These percentages describe the registry entries; they do not establish comparative risk, causal attribution, or the likelihood of an event for an individual.

Across the record, the distinction between a prespecified endpoint, an observed outcome, and an exploratory or descriptive safety summary is important. A protocol or statistical analysis plan would clarify planned analyses and conventions, but those details are not reported in the registry record. The listed endpoint definition and safety counts can be described, while unreported inferential methods and results must remain unresolved.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 33 outcome measures and two analyses. It describes the primary-arm analysis as hypothesis-driven and the secondary-arm analysis as non-hypothesis-driven, but does not report how the primary hypothesis was specified or how any additional outcome tests were handled. A multiplicity strategy—such as an ordering of hypotheses or an adjustment to control false-positive findings across multiple tests—is not reported in the registry record. The number of outcomes alone does not establish that all were tested or that an adjustment was required or applied.

The record does not report an analysis plan addressing missing endpoint information, loss to follow-up, exclusions, or the handling of participants who do not have an evaluable outcome. It does not identify the analysis populations, such as whether participants are analyzed according to enrollment, implantation, or availability of endpoint data. These definitions matter because they determine who contributes to each estimate and how missing observations affect the interpretation. They cannot be inferred from the enrollment field or arm descriptions.

The registry record also does not report a protocol-defined interim analysis schedule, stopping rules, or the handling of repeated looks at accumulating data. Their presence or absence should not be assumed. The primary endpoint result and its precision are not reported, so no inference about missingness or multiplicity can be made from that endpoint's estimate.

In general, multiplicity concerns arise when multiple outcomes, groups, or repeated tests are considered, because the chance of at least one apparently notable result can depend on the analysis strategy. Missing-data methods likewise require assumptions about why data are absent and how that absence relates to outcomes. Neither issue can be resolved by the outcome count alone. The registry record does not provide the details needed to evaluate these aspects of the analysis.

11. 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: acute kidney injury (5.9%), non st segment elevation myocardial infarction (3.9%), spinal cord ischemia (3.9%), atrial fibrillation (2.9%), chronic systolic heart failure (2.9%).

For the primary study arm, the serious-adverse-event fields record 52 affected among 102 at risk, and the other-adverse-event fields record 92 affected among 102 at risk. The registry also records 6 deaths. The record does not specify in the registry entries whether deaths were related to the device or procedure, or how they relate to the adverse-event fields. These values are descriptive entries, not a comparison with another treatment.

The listed top serious terms are acute kidney injury at 5.9%, non ST segment elevation myocardial infarction at 3.9%, spinal cord ischemia at 3.9%, atrial fibrillation at 2.9%, chronic systolic heart failure at 2.9%, and congestive cardiac failure aggravated at 2.9%. They identify terms recorded in the registry, but their percentages do not by themselves indicate causation or severity beyond the term classification. The record does not provide event-specific timing, adjudication details, or additional denominators for these terms.

Serious and other adverse-event categories may include overlapping participants, and a participant can experience more than one event. The registry entries do not clarify overlap or repeated events. The figures should therefore be read as registry safety summaries, not added together or interpreted as unique people or a measure of comparative risk.

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

The record establishes that a prospective, non-randomized, multicenter study evaluated the GORE EXCLUDER Thoracoabdominal Branch Endoprosthesis in two independent arms. It defines a primary composite endpoint that combines technical success with freedom from specified procedural safety events. It also records adverse-event summaries for the primary study arm. These details help explain what the study set out to assess and what safety information was recorded.

The record does not report the primary endpoint result. It therefore does not establish the proportion meeting the composite definition, the precision of that proportion, or the frequency of each component of the primary endpoint. Without those results, the endpoint's observed performance cannot be assessed from this record. The endpoint definition describes a measurement target, not a finding.

The safety counts and listed event percentages describe events recorded in the primary arm, but they do not show whether those events were caused by the device or procedure. The record does not describe a comparable control group. It also does not provide enough information to interpret the listed counts as a comparative safety effect or to determine whether event rates differ from another treatment or population.

The two arms are not interchangeable comparison groups. They concern different aneurysm types and different device configurations, and allocation is non-randomized. A difference between arms, were one reported, could not be attributed to the device configuration alone without a suitable analysis and assumptions addressing those differences. The registry record does not report such a comparative analysis.

In general, a study's result is best interpreted alongside its design, endpoint definition, analysis population, estimate, and uncertainty. Here, the design and endpoint are described, but the primary result, analysis populations, missing-data approach, and detailed statistical plan are not reported in the registry record. The study details and descriptive safety entries can be stated, but they do not support a conclusion that the intervention is effective or ineffective, or that its risks are higher or lower than those of an alternative.

13. Why This Trial Matters Statistically

This trial is statistically notable because its primary endpoint joins procedural technical success with freedom from a collection of safety events. That structure makes the outcome clinically broad, but also means a single composite result would need component-level context. Without the component results, readers could not tell whether the combined outcome was shaped chiefly by technical requirements or by a particular safety event. The registry record does not report the primary endpoint result or component-level results.

The non-randomized design is central to interpretation. The two independent arms address different aneurysm groups and use different device configurations. Those features make the arms unsuitable as a simple treated-versus-control comparison. Statistical adjustment can sometimes address measured differences, but it cannot automatically remove unmeasured confounding, and the registry record does not describe an adjusted comparative analysis.

The record also distinguishes a hypothesis-driven primary-arm analysis from a non-hypothesis-driven secondary-arm analysis. That distinction signals different analytical purposes, but the hypotheses, statistical methods, and multiplicity strategy are not reported. The listing of 33 outcome measures and two analyses does not by itself reveal which results were confirmatory or how uncertainty across analyses was handled.

Finally, the record contains meaningful descriptive safety entries while leaving key interpretive details unavailable, including event timing, analysis populations, and missing-data handling. This illustrates why event counts should be read together with denominators, follow-up definitions, and attribution methods. The study provides a framework for evaluating an endovascular device in distinct clinical groups; the registry information available does not supply the primary outcome evidence needed to judge its observed performance.

14. 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 or procedural performance is that the primary endpoint result is not reported in the registry record. Neither an estimate of the composite outcome nor its uncertainty is available in the registry record described. The endpoint components are defined, but component-specific outcomes are not reported.

The study is non-randomized and has no described control arm. Its two arms differ by aneurysm type and device configuration, so they cannot be treated as equivalent groups for a causal comparison. The record does not describe adjustment for baseline differences or provide a comparative effect estimate.

There is a difference between the registry's enrollment field, which records 102, and the brief summary's statement of a minimum of 122 implanted participants and a maximum of 202 implanted participants, including up to 65 additional participants in continued access under the primary arm. The arm descriptions also state n= 102 for the primary arm and n= 20 - 100 for the secondary arm. The record does not reconcile these statements. Enrollment, implanted participants, and analyzed participants should not be assumed to be the same population.

Further limitations are the absence of reported analysis populations, missing-data methods, detailed statistical methods, and multiplicity strategy. The adverse-event summaries lack additional details in the registry entries about event timing, overlap, adjudication, and attribution. The registry status is active, not recruiting, but that status does not fill in the missing outcome or analysis information. These limitations restrict interpretation to the recorded design features and descriptive safety information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Evaluation of the GORE® EXCLUDER® Thoracoabdominal Branch Endoprosthesis in the Treatment of Thoracoabdominal and Pararenal Aortic Aneurysms — NCT03728985.
• Registry record last updated 2026-09-02; status last verified 2026-08.
• Results first posted 2024-08-05.
• 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.

18. Record Summary

NCT03728985 is a prospective, non-randomized, multicenter evaluation sponsored by W.L.Gore & Associates. It evaluates the GORE EXCLUDER Thoracoabdominal Branch Endoprosthesis in two independent arms: a primary arm for Crawford Type IV thoracoabdominal and pararenal aneurysms using the TAMBE System alone, and a secondary arm for Crawford Type I-III aneurysms using TAMBE with CTAG device or devices. The record lists no masking and a parallel model.

The primary endpoint is the percent of participants with uncomplicated technical success and freedom from a procedural safety composite event, with a timeframe from the start of the index procedure to 59 days post procedure. The primary endpoint result is not reported in the registry record. Descriptive primary-arm safety fields list 52 affected among 102 at risk for serious adverse events, 92 affected among 102 at risk for other adverse events, and 6 deaths. The record does not provide a randomized comparator or enough detail to interpret these entries as comparative effects.