The Angel® Catheter Pivotal Clinical Trial: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Angel® Catheter Pivotal Clinical Trial (NCT02186223), a na na study. The primary outcome is Freedom From Clinically Significant PE or Fatal PE During Treatment Period.

2. Clinical Question

3. Trial Design

The Angel® Catheter Pivotal Clinical Trial, registered as NCT02186223, is described as a multicenter, prospective, single-arm clinical trial. Its stated objective was to evaluate the safety and effectiveness of the Angel® Catheter in subjects at high risk of PE who had recognized contraindications to anticoagulation. The intervention is classified as a device, and the arm description says eligible subjects would receive the catheter.

The record lists the study as completed, with enrollment of 172. It gives a start date of 2015-01 and a primary completion date of 2015-12. The phase is listed as NA. Allocation is also listed as NA, the model as single group, and masking as none. These entries describe a study without a randomized comparison or masking; they do not support a controlled estimate of the catheter’s effect relative to another treatment.

The primary endpoint concerns freedom from clinically significant PE or fatal PE during the treatment period. Secondary outcomes include acute proximal deep vein thrombosis, catheter-related thrombosis, catheter-related bloodstream infections, major bleeding, and PEs averted. The registry lists 6 outcome measures, but does not report analysis results for the primary endpoint. It lists 0 analyses. The primary endpoint result, the methods used to analyze it, and the analysis population are not reported in the registry record.

The adverse-event record uses a risk count of 163 for serious events and a risk count of 163 for other events, alongside affected counts of 49 and 114, respectively. Those risk counts do not match the enrollment figure, and the reason for the difference is not reported in the registry record. They should be read as the denominators stated for the adverse-event entries, not as an explanation of enrollment or follow-up.

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.

Population: Population includes all subjects that had the Angel® Catheter placed.

6. Primary Endpoint

The registry lists the primary outcome as Freedom From Clinically Significant PE or Fatal PE During Treatment Period, measured over Assessed daily from Baseline through Study Exit which occurs 3 days post-Angel Catheter Removal OR at hospital discharge, whichever is first (maximum of 33 assessment days with an anticipated average of 7 days).

The primary endpoint is titled “Freedom From Clinically Significant PE or Fatal PE During Treatment Period.” It is measured as a count of participants. The registry describes daily assessment for signs and symptoms of PE from baseline through study exit. When PE was suspected and no alternative diagnosis was suspected, at least one of four defined diagnostic examinations was to be performed to confirm or rule out PE. Fatal PE was defined as unexpected death within 24 hours of onset of the acute event, with a verified initial symptomatic deep vein thrombosis or PE and no other reasonable cause of death.

This kind of endpoint is intended to capture clinically consequential events during the defined treatment period, rather than relying only on a laboratory measure or a less direct indicator. Combining clinically significant PE with fatal PE places event ascertainment around serious outcomes relevant to the trial’s stated objective. The registry description gives the assessment framework, but the primary endpoint count and analysis are not reported in the registry record. Consequently, the record does not show how many participants met the definition of freedom from these events or how precisely that outcome was estimated.

In general, an endpoint’s usefulness depends on clear definitions, consistent assessment, and complete outcome ascertainment. The registry provides definitions and an assessment schedule, but does not report adjudication procedures, missing endpoint data, or the statistical analysis used. Those omissions limit interpretation of the endpoint beyond its stated intended meaning.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a prospective, multicenter, single-group study. Prospective designs define the intended observations before outcomes are collected, which can help establish a planned sequence of intervention and assessment. Multicenter recruitment can include participants treated at more than one site, but the registry does not report the number of sites or how site differences were handled. A single-group design means the record does not describe a concurrent control group. Therefore, a comparison of outcomes between randomized treatment groups is not available.

What does a single-group count tell the reader?

In general, a count tells how many participants in the analyzed group experienced a defined event or outcome. It is descriptive unless paired with a suitable design and analysis that support a comparative or causal interpretation. A count of participants who remained free from an event is not itself evidence that an intervention prevented the event: interpretation also depends on the underlying risk, follow-up, eligibility, and what would have occurred under an alternative. The primary outcome count is not reported in the registry record, so even a descriptive primary endpoint interpretation is unavailable.

How should the primary endpoint be understood?

The endpoint combines freedom from clinically significant PE or fatal PE during the treatment period. The registry describes daily assessment and defines the clinical events. In general, combining outcomes can make an endpoint capture more than one clinically important way an intervention may fail, but the interpretation depends on the component definitions and the frequency of each component. Component-specific primary outcome counts are not reported in the registry record. Nor are the details of diagnostic adjudication or the statistical procedure for combining the components.

The stated assessment window runs from baseline through study exit, which occurs 3 days after catheter removal or at hospital discharge, whichever is first. The registry also states a maximum of 33 assessment days and an anticipated average of 7 days. These describe the planned observation window, not the actual follow-up distribution. Actual follow-up duration and completeness are not reported in the registry record. In general, variation in time under observation matters because participants observed for different durations have different opportunities for an event to be detected. A time-to-event analysis can account for such variation when its assumptions and data are appropriate, but the registry lists no analyses and does not report whether such a method was used.

What do the safety counts represent?

The adverse-event entries report affected counts and counts at risk. In general, the count at risk is the stated denominator for interpreting the associated count; it should not automatically be replaced with the enrollment figure. The record lists 163 at risk for each of the serious and other adverse-event entries. It does not explain the relationship between those denominators and enrollment of 172. The registry lists 49 affected for serious events and 114 affected for other events. These are counts, not comparative effects. They also should not be assumed to be mutually exclusive participant groups: event categories can involve the same participant, and the record does not describe whether the counts refer to participants with at least one event or to event episodes in detail.

The record lists serious-event terms with percentages: deep vein thrombosis, 6.1%; pneumonia, 3.7%; respiratory failure, 3.7%; intracranial pressure increased, 3.1%; cardiac arrest, 2.5%; and craniocerebral injury, 2.5%. These percentages are reported values and should not be treated as proof of attribution to the device. The record does not report the event-coding conventions, seriousness definitions beyond the listed classification, or whether events were independently adjudicated.

How should precision and uncertainty be assessed?

In general, an estimate is more informative when accompanied by an uncertainty interval. A confidence interval describes uncertainty around an estimate under a statistical model and its assumptions. A narrow interval indicates greater precision than a wide interval, but neither width nor interval coverage resolves bias from selection, missing observations, or lack of a comparator. The registry does not report a primary endpoint estimate, confidence interval, or analysis result. No precision assessment of the primary outcome can therefore be made from the record.

The registry describes a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect defined as a stated fraction of the observed effect. The illustration is not the trial’s own design justification and should not be interpreted as observed power or as evidence about the trial’s outcome. The actual trial is listed as single group, so the equal-allocation two-arm planning assumptions do not describe its recorded design. The sample-size justification, target effect, and statistical plan for the trial are not reported in the registry record.

What is not established by the design?

Randomization can, in general, make treatment groups more comparable by balancing measured and unmeasured factors on average. This study is not recorded as a randomized comparison, and no control arm is described. As a result, its design cannot isolate the catheter’s effect from other factors using a between-group contrast. Masking is listed as none; the record does not describe how that could have affected outcome assessment or clinical decisions. The methods needed to evaluate those potential sources of bias, including the statistical analysis plan and endpoint adjudication procedures, are not reported in the registry 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("The Angel® Catheter")
n      <- c(163)
events <- c(163)
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  The Angel® Catheter  163  163  100.0  97.8  100.0  97.7  100.0  97.8  100.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 6 outcome measures, including the primary endpoint and secondary outcomes concerning acute proximal deep vein thrombosis, catheter-related thrombosis, catheter-related bloodstream infections, major bleeding, and PEs averted. It lists 0 analyses. The results and analysis methods for these outcomes are not reported in the registry record.

In general, multiplicity arises when several outcomes or statistical tests are considered. Looking across multiple outcomes can increase the chance of an apparently notable result arising by chance, so interpretation commonly depends on which endpoint was designated primary, how secondary outcomes were treated, and whether an adjustment or hierarchy was prespecified. The registry identifies a primary endpoint, but a multiplicity strategy, endpoint hierarchy beyond that designation, and inferential testing plan are not reported in the registry record. Without outcome results or a stated plan, it is not possible to assess how multiplicity would affect interpretation.

Missing-data methods matter because incomplete outcome assessment can affect both the count and the population to which a result applies. The registry describes daily assessment during the treatment period, but does not report endpoint completeness, reasons for missing observations, imputation methods, or sensitivity analyses. The analysis population is also not reported. Enrollment of 172 and adverse-event risk counts of 163 are recorded, but the reason these figures differ is not reported; no explanation of missingness or exclusion should be inferred from the counts alone.

Interim analyses and stopping rules are not reported in the registry record. The statistical plan and sample-size justification for the trial are also not reported. These omissions do not establish that particular procedures were absent; they mean the registry does not document them.

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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: deep vein thrombosis (6.1%), pneumonia (3.7%), respiratory failure (3.7%), intracranial pressure increased (3.1%), cardiac arrest (2.5%).

The registry lists 49 affected for serious adverse events among 163 at risk, and 114 affected for other adverse events among 163 at risk. These are descriptive counts for the Angel® Catheter group. They are not controlled comparisons, and the registry does not report a causal attribution analysis. The adverse-event denominator is not the enrollment figure of 172; why it differs is not reported in the registry record.

The listed serious-event terms include deep vein thrombosis at 6.1%, pneumonia at 3.7%, respiratory failure at 3.7%, intracranial pressure increased at 3.1%, cardiac arrest at 2.5%, and craniocerebral injury at 2.5%. These entries describe events recorded in the registry. They do not establish that the catheter caused those events, and they should not be read as comparative risks against a control group. The record does not explain whether the term-specific percentages refer to participants or event episodes, or report the methods used for event attribution and adjudication.

In general, safety counts are most interpretable when the event definitions, observation period, denominator, and handling of repeat events are clear. Here, the registry states counts at risk but does not report the detailed safety-analysis methods or the relationship between the adverse-event population and the enrolled population. The listed counts therefore provide a limited descriptive account, not a complete comparative safety assessment.

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

The record establishes that the Angel® Catheter was evaluated in a prospective, multicenter, single-arm study targeting subjects at high risk of PE with recognized contraindications to anticoagulation. It describes the intended primary endpoint, the period of assessment, and a set of secondary outcomes. It also provides adverse-event counts and selected serious-event terms. These details help identify the clinical question and the kind of observations the study was designed to collect.

The record does not report the primary endpoint result or any analysis results. It therefore does not show how many participants were free from clinically significant PE or fatal PE, nor does it give an estimate of uncertainty around that outcome. The stated objective to assess safety and effectiveness is an objective, not a result. A completed study status does not fill the gap in outcome reporting.

Even if a single-group primary outcome count were available, it would describe outcomes within the catheter group rather than a randomized comparison. In general, it would not establish what would have happened to comparable participants without the catheter or under another treatment. Factors such as the subjects’ underlying risk, their clinical care, and the period of observation can influence outcomes. The registry does not provide comparative data to separate those influences from an intervention effect.

The adverse-event figures likewise do not prove causation. They report affected counts in the study group, without a control arm or a reported attribution method. The counts at risk and enrollment figure differ, and the reason is not reported. This prevents confident interpretation of how the safety denominators relate to the enrolled cohort. The registry’s listed event terms can be read as descriptive safety information, but not as a controlled estimate of device-related risk.

In general, a result is most useful when the endpoint definition, analysis population, missing-data handling, estimate, and uncertainty are all reported. Here, several of those elements are unavailable in the registry record. The appropriate conclusion is limited: the record describes the study design and selected safety data, while the primary outcome and statistical analysis needed to assess its result are not reported.

14. Why This Trial Matters Statistically

This study illustrates an important statistical distinction between collecting outcomes and reporting evidence about an outcome. The registry specifies a clinically focused primary endpoint and an assessment schedule, but does not report the endpoint result or an analysis. Without those, readers cannot assess the observed outcome frequency or its precision, regardless of the study’s stated objective or completed status.

The single-group design is also important. Device studies may evaluate outcomes in a defined clinical population, but descriptive observations in one group answer a different question from randomized comparisons. A single-arm study can document what happened during follow-up among participants who received the device. It cannot, on its own, establish how outcomes would differ under an alternative approach. This limitation is especially relevant when the target population is described as high risk and has contraindications to standard pharmacological therapy, since the population and treatment context may differ from those in other studies.

The record also demonstrates why denominators need to be interpreted carefully. Enrollment is listed as 172, while the adverse-event entries use 163 at risk. Without a reported explanation, readers should not assume these counts represent identical analysis populations or infer why they differ. Transparent reporting of who was assessed, who contributed to each outcome, and how incomplete observations were handled is essential to understanding event counts.

Finally, listing several secondary outcomes does not substitute for reporting their results or the plan for interpreting multiple outcomes. A clear distinction among the primary question, secondary questions, analysis methods, and safety summaries helps readers understand what conclusions are supported. In this record, the design and intended endpoints are available, but the results and key analysis details are not. That separation between protocol-style information and outcome evidence is the central statistical lesson.

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 count and analysis are not reported in the registry record. This prevents description of the observed primary outcome and assessment of its statistical precision. The record lists 0 analyses, and no effect estimate or confidence interval is reported.

The study is listed as single group, with allocation NA and masking none. No concurrent control group is described, so the registry record does not support a randomized comparative interpretation. The record does not report the statistical plan, sample-size justification, analysis population, or endpoint adjudication procedures.

The endpoint assessment period is described, but actual follow-up duration and completeness are not reported. Missing-data methods and sensitivity analyses are not reported. Enrollment of 172 differs from the adverse-event risk count of 163; the reason is not reported in the registry record. No interpretation of that difference should be assumed.

The registry lists several secondary outcomes, but their results and a multiplicity strategy are not reported. It also does not report interim analyses or stopping rules. The serious-event terms and counts are descriptive, while methods for event attribution, coding, and repeat events are not reported. These limitations constrain both outcome interpretation and safety assessment; they do not establish that unreported procedures or information were absent from the study itself.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The Angel® Catheter Pivotal Clinical Trial — NCT02186223.
• Registry record last updated 2017-04-04; status last verified 2017-02.
• Results first posted 2017-04-04.
• 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

NCT02186223 is listed as a completed, prospective, multicenter, single-arm device study of the Angel® Catheter. The registry describes a target population at high risk of PE with recognized contraindications to anticoagulation, enrollment of 172, and a primary endpoint of freedom from clinically significant PE or fatal PE during the treatment period.

Allocation is listed as NA and masking as none. The registry lists 6 outcome measures and 0 analyses. The primary endpoint result is not reported in the registry record. Adverse-event entries list 49 affected for serious events and 114 affected for other events, each with 163 at risk; the reason those denominators differ from enrollment is not reported.

The record supports description of the trial’s design, intended outcomes, and selected safety counts. It does not provide the primary result, comparative evidence, or the statistical details needed to assess outcome precision.