Caterpillar™ Arterial Embolization Device Post-Market Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Caterpillar™ Arterial Embolization Device Post-Market Study (NCT04244370), a na na study. The primary outcome is Technical Success.

2. Clinical Question

The study concerns use of the Caterpillar™ Arterial Embolization Device for arterial embolization in the peripheral vasculature. Its stated objective is to evaluate device performance and safety in a real-world, on-label application. The registry record describes a prospective, multicenter study with a single group, rather than a comparison of assigned treatments. Placement was by percutaneous transcatheter embolization.

The listed secondary outcomes address occlusion timing, recanalization, acute and non-acute migration, device- or procedure-related adverse events, delivery accuracy, trackability or deliverability, and detachment. These outcomes indicate a range of procedural and safety interests, but their results are not reported in the registry record. The question addressed is therefore descriptive: what performance and safety outcomes were recorded for device use in this study? The available record does not establish how those outcomes compare with another approach.

3. Trial Design

The registry identifies this as a prospective, multicenter, single-arm, real-world study of a device. It is marked as completed, with a stated enrollment of 50. The phase is listed as not applicable, allocation is listed as not applicable, and masking is listed as none. These classifications fit a study that records device use without assigning participants to competing intervention groups. The registry lists C. R. Bard as the sponsor.

The study period recorded in the registry begins on 2020-04-30, with primary completion on 2021-08-13. The intervention is placement of the Caterpillar™ Arterial Embolization Device via percutaneous transcatheter embolization. The broad condition listed is therapeutic embolization. The record does not give additional site-level or participant-level eligibility criteria, the number or characteristics of participating centers, or detailed descriptions of clinical practice.

A single-arm design can describe what occurred among those who received the device, including procedural outcomes and adverse events. It cannot, by itself, separate the contribution of the device from other influences on the observed outcomes. Those influences may include the treated anatomy, the underlying clinical condition, procedural decisions, operator experience, and follow-up practices. Without a concurrent comparison group or another justified comparison, observed outcomes should not be interpreted as estimates of relative performance against another treatment.

The primary endpoint is assessed during the index procedure and is defined at the target embolization-site level. The registry also lists secondary outcomes that concern later occlusion status and migration, as well as procedural usability and adverse events. Their assessment windows and detailed operational definitions are not reported in the registry record beyond the primary endpoint timeframe and the outcome names.

The registry record does not report the protocol’s sample-size justification, a detailed statistical analysis plan, interim analyses, or the analysis populations. It also records no analyses. The absence of those details limits assessment of how outcomes were intended to be summarized, how missing observations were handled, and whether planned methods were changed. The design should therefore be read from the information explicitly recorded: a prospective, multicenter, single-group device study, not a randomized or masked comparative trial.

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 Technical Success, measured over During the Index Procedure.

The primary endpoint is technical success during the index procedure. It concerns target embolization sites, with success defined as occlusion confirmed by the investigator through angiographic assessment. The registry states that technical success is reported for each target site, so the endpoint’s unit is the site rather than a general judgment about the study as a whole.

This type of endpoint is used to describe whether the intended procedural result was achieved at the point of treatment. Angiographic confirmation provides an imaging-based basis for judging occlusion during the procedure. In general, a clearly defined procedural endpoint helps make the intended outcome explicit and supports consistent interpretation across cases. It does not, on its own, describe durability, later clinical outcomes, or safety over follow-up; those questions require separate outcomes and observation periods.

The record names secondary outcomes related to time point of occlusion and freedom from recanalization, as well as migration and other device- or procedure-related outcomes. These address issues beyond immediate technical success. However, the registry record does not report the observed primary endpoint result, its numerator or denominator, an uncertainty interval, or a statistical analysis. It also does not provide the criteria used to resolve ambiguous angiographic assessments. The endpoint definition can therefore be described, but its observed frequency and 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 observations are converted into estimates and how much uncertainty should be attached to those estimates. In this study, the registry describes a single group and a site-level primary endpoint. It does not report a statistical analysis plan or analyses. The explanations below are general statistical context, not a claim about methods actually used in the study.

What does a site-level endpoint imply?

The primary endpoint is defined for each target embolization site. In general, a binary endpoint records whether each site meets the success definition or does not. A summary could express the number meeting the definition relative to the number assessed, but the registry record does not report either count for technical success. It also does not specify whether sites within the same participant were handled as statistically independent. If a participant contributes multiple sites, those observations may share clinical and procedural features. Treating related observations as independent can make uncertainty estimates too narrow; methods that account for clustering may be needed when such dependence is present. The registry record does not say whether participants contributed multiple sites or how any clustering was handled.

Why do confidence intervals matter?

In general, a confidence interval communicates the precision of an estimated outcome by presenting a range of values compatible with the data under the method’s assumptions. An estimate without an interval can conceal substantial uncertainty, especially when the amount of information is limited. A confidence interval does not guarantee that the true value lies within its endpoints, nor does it correct for bias, missing data, or a poorly chosen analysis. No confidence interval for technical success is reported in the registry record, so its precision cannot be assessed.

What can a single group establish?

In general, a single-group estimate describes outcomes observed among people receiving the intervention. A comparative effect requires a comparator and a defined contrast. Randomization can help balance measured and unmeasured baseline factors across groups on average, while an observational or single-arm design generally cannot ensure that alternative explanations have been controlled. This study is listed as single-group, with allocation not applicable and masking none. The record therefore does not support a randomized treatment contrast. A comparison with historical or external data would require explicit sources and methods, which are not reported in the registry record.

How should planning illustrations be read?

The registry-related planning assumptions describe illustrations based on an observed effect, not the study’s own design. They specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a stated fraction of the observed effect. For time-to-event illustrations, the assumption is that the reported quantity is the total number of events using the Schoenfeld approach; other illustrations are expressed as participants per arm. These are hypothetical planning conventions, not evidence that the trial enrolled two arms, used those methods for its analysis, or had a particular probability of detecting an effect. The registry record does not report its sample-size justification. Planning values should not be called observed power: power is a design concept, while a post hoc calculation based on an observed estimate does not establish the study’s ability to detect a true effect.

Why can over-dispersion matter?

In general, count outcomes are sometimes analyzed with a model that assumes a particular relationship between the mean and variability. Over-dispersion means that observed variability is greater than the model expects. If ignored, standard errors can be underestimated and intervals or tests can appear more precise than warranted. This is relevant as a general consideration for some count outcomes, but the primary endpoint is described as a count of target sites with technical success rather than a reported rate model. The registry record does not state that a count model, a dispersion adjustment, or any particular inferential method was used.

What is the role of significance tests?

In general, a p-value assesses how compatible the observed data are with a specified statistical model and null hypothesis. It does not measure the size or clinical importance of an effect, and it is not the probability that a hypothesis is true. A test also depends on the analysis plan, assumptions, and completeness of the data. No p-value or statistical test for the primary endpoint is reported in the registry record. Given the absence of a comparator, a treatment-versus-control hypothesis test cannot be inferred from the design description.

The record reports no analyses. It does not describe the estimator, uncertainty method, handling of multiple sites, adjustment variables, analysis population, or approach to missing outcomes. Those omissions prevent a full audit of statistical validity. The endpoint definition and design can be explained, but the actual statistical analysis and the precision of its findings are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 11 outcome measures, including technical success as the primary outcome and secondary outcomes concerning occlusion, recanalization, migration, adverse events, delivery, trackability or deliverability, and detachment. Multiple outcomes raise a general interpretive issue: examining many endpoints can increase the chance of finding an apparently notable result by chance, particularly when many hypothesis tests are conducted. In general, a prespecified primary endpoint and a clear multiplicity strategy help readers distinguish confirmatory analyses from exploratory ones.

A multiplicity adjustment, hierarchy, or other strategy for handling multiple outcomes is not reported in the registry record. The record also lists no analyses, so it is not possible to determine which outcomes were analyzed, whether statistical tests were performed, or whether any adjustment was applied. The secondary outcome names alone do not establish that results were available or that they were analyzed as confirmatory endpoints.

Missing-data methods and the amount or pattern of missing outcome information are not reported in the registry record. The analysis populations are also not described. In general, missing observations can affect an estimate if the likelihood of being observed is related to outcome status. Different assumptions about missingness can produce different results, so a transparent report would identify who was included, the information available for each endpoint, and any imputation or sensitivity analyses. None of those details can be assessed from the registry record.

The record’s enrollment and safety counts do not identify the denominator used for the primary technical-success outcome. Nor does the record say whether every enrolled participant or target site contributed to each outcome. Consequently, the completeness of endpoint ascertainment and the representativeness of any analyzed group cannot be evaluated. These are reporting gaps, not evidence that data were necessarily missing or that a particular analysis was inappropriate.

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: sepsis (4.0%), obstruction gastric (2.0%), acute kidney injury (2.0%), pancytopenia (2.0%), ascites (2.0%).

The registry records serious adverse events for the Caterpillar™ device group as 11 affected among 50 at risk. Other adverse events are recorded as 6 affected among 50 at risk, and deaths as 5. These are descriptive counts in the registry record; they should not be interpreted as estimates of device-caused harm. The record does not provide event timing, participant-level histories, causes of death, or a comparison group that could help distinguish background risk from treatment-related risk.

The listed serious-event terms include Sepsis at 4.0%, Obstruction Gastric at 2.0%, Acute Kidney Injury at 2.0%, Pancytopenia at 2.0%, Ascites at 2.0%, and Gastrointestinal Haemorrhage at 2.0%. The registry record does not provide enough context to determine whether these terms overlap within individuals, how events were adjudicated, or whether they were considered related to the device or procedure. The percentages should be retained as reported rather than treated as causal risks.

The study also names freedom from device- or procedure-related adverse events as a secondary outcome, but its result is not reported in the registry record. The adverse-event counts therefore offer only limited descriptive safety information. They do not establish incidence over a specified follow-up period, comparative safety, or causation.

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

The record establishes that a prospective, multicenter, single-arm study was conducted to evaluate the Caterpillar™ Arterial Embolization Device in peripheral arterial embolization. It describes the intended setting as real-world and on-label, identifies technical success as the primary outcome, and defines success as investigator-confirmed angiographic occlusion of target sites during the index procedure. These details clarify what the study set out to assess.

The record does not report the observed technical-success result. It therefore does not show how many target sites met the definition, what proportion that represented, or how precisely the result was estimated. The lack of a reported result should not be mistaken for a failed outcome, a successful outcome, or a null finding. It means the primary estimate cannot be evaluated from the registry record.

The safety information is also descriptive and incomplete. Serious adverse events, other adverse events, and deaths are recorded for the study group, but the record does not establish causal attribution or supply comparative data. Terms and percentages listed for serious events do not reveal their timing or individual clinical context. The named secondary outcomes could provide additional information about occlusion, migration, usability, and safety, but their observed results are not reported in the registry record.

The design limits what can be concluded even if outcome estimates are available elsewhere. With no comparator group, the study cannot by itself show that outcomes are better or worse than those under another device or procedure. It also cannot isolate the device’s contribution from other clinical and procedural factors. A real-world setting may describe use under routine conditions, but it does not remove confounding or make a single-group result comparative.

Accordingly, the registry record supports a description of the study’s purpose, design, endpoint definitions, and recorded safety counts. It does not support a conclusion about the device’s efficacy, comparative performance, durability, or causal safety profile. Those conclusions would require outcome results and appropriate supporting information, neither of which is reported in the registry record for the primary endpoint.

13. Why This Trial Matters Statistically

This study is statistically important to read as a device-performance study rather than as a treatment comparison. Its prospective, multicenter, single-arm structure makes the intended descriptive question clear: what procedural and safety outcomes were recorded when the device was used in the stated setting? That is a legitimate question, but it differs from asking whether the device improves outcomes relative to another option.

The primary endpoint also illustrates why the unit of analysis matters. Technical success is defined for target embolization sites, not merely as a general participant-level judgment. If observations are clustered within participants or centers, appropriate analysis may need to account for that dependence. The registry record does not report whether that circumstance applied or how it was handled. Without the outcome estimate and analysis details, readers cannot assess either the endpoint’s observed frequency or its statistical precision.

The case further shows the distinction between a registered endpoint and a reported result. A precise operational definition helps readers understand what was intended to be measured, but it cannot substitute for the estimate, denominator, uncertainty interval, and analysis population. Those elements are not reported for technical success in the registry record. The listed safety counts add some descriptive information, while leaving timing and causal attribution unresolved.

Finally, planning illustrations should not be confused with the trial’s design or evidential strength. The stated planning assumptions describe hypothetical two-arm calculations based on an observed effect; the trial itself is single-arm. Such illustrations can help frame planning questions in general, but they do not demonstrate observed power or supply the missing outcome results. Keeping the design, planned calculations, and observed evidence conceptually separate is essential to a sound statistical reading of this record.

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.

Several limitations specific to this record constrain interpretation. It describes a single-arm study and no comparator, so any recorded outcomes cannot establish relative performance against another device, procedure, or standard of care. The registry labels allocation as not applicable and masking as none. Without a comparison group, confounding and selection effects cannot be ruled out through the design information reported.

The primary endpoint result is not reported in the registry record. There is no technical-success count, denominator, estimate, or uncertainty interval in the information available. Although the endpoint is defined at the target-site level, the record does not explain whether individual participants could contribute multiple sites or how any within-participant dependence was handled. Nor does it report adjudication procedures or agreement among investigators for angiographic assessment.

The record gives limited information about the population and setting. Detailed inclusion and exclusion criteria, participant characteristics, center characteristics, and follow-up completeness are not reported in the registry record. The study is described as real-world and on-label, but that description alone does not show how representative the enrolled population was or whether results would generalize to other settings.

Safety interpretation is constrained by the absence of timing, causes, relatedness assessments, and individual event context. The reported counts do not establish causation, and the record does not provide a control group for comparison. The secondary outcomes are named, but their observed results and detailed assessment windows are not reported in the registry record.

Finally, no analyses are recorded, and the statistical plan, analysis populations, missing-data handling, multiplicity strategy, and sample-size justification are not reported. These gaps make it impossible to verify how the planned endpoints were analyzed or how robust any estimates would be. They limit the conclusions that can be drawn from the registry record; they do not, by themselves, establish that the study was conducted improperly.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Caterpillar™ Arterial Embolization Device Post-Market Study — NCT04244370.
• Registry record last updated 2023-07-25; status last verified 2023-07.
• Results first posted 2022-10-12.
• 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

NCT04244370 is a completed, prospective, multicenter, single-arm study of the Caterpillar™ Arterial Embolization Device for peripheral arterial embolization. The registry lists enrollment of 50, identifies C. R. Bard as sponsor, and records the study period from 2020-04-30 to primary completion on 2021-08-13. The intervention was device placement via percutaneous transcatheter embolization.

The primary endpoint is technical success at target embolization sites during the index procedure, defined as investigator-confirmed occlusion by angiographic assessment. The registry record does not report the primary endpoint result or any analyses. Serious adverse events are recorded as 11 affected among 50 at risk, other adverse events as 6 among 50, and deaths as 5. The record does not establish that these events were caused by the device or procedure. With no comparator group and no reported primary outcome estimate, the record supports design and safety-count description, not a comparative conclusion.