Pilot Study of the Contour Neurovascular SystemTM: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pilot Study of the Contour Neurovascular SystemTM (NCT02784431), a na phase not stated study. The primary outcome is Percentage of Subjects With Major Ipsilateral Stroke/SAH or Death Due to Neurologic Cause Within Six (6) Months After Treatment..

2. Clinical Question

3. Trial Design

The registry describes a prospective, single-arm, multi centre study evaluating the safety and performance of the Contour Neurovascular System in the treatment of intracranial aneurysm. The listed intervention is Contour Neurovascular System placement. The study title identifies it as a pilot study, and enrollment is listed as 20. That enrollment figure does not establish how many participants were successfully implanted or contributed data to the primary endpoint.

The record lists a start date of 2016-07 and primary completion of 2018-10. Its current status is TERMINATED. The reason for termination is not reported in the registry record, so the status alone does not explain whether termination related to recruitment, safety, logistics, or another consideration.

Allocation is listed as NA, the model as SINGLE GROUP, and masking as NONE. These features describe a study without a randomized comparator and without masking. Consequently, the study is structured to report observations after device placement, rather than to estimate a contrast between treatment arms. The registry record does not report a control group or a concurrent comparison strategy.

The primary outcome concerns major ipsilateral stroke or SAH, or death due to a neurologic cause, within 6 months after treatment. The stated primary population is patients who were successfully implanted with the device. Occlusion Status of the Target IA is listed as a secondary outcome. Although the registry lists 2 outcome measures, it lists 0 analyses. Results for these outcomes are not reported in the registry record. The available record therefore describes the design and questions being studied but does not provide an efficacy or primary safety estimate.

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:

Analysis population for the primary outcome, as defined in the registry: Patients who were successfully implanted with the Contour device.

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 Percentage of Subjects With Major Ipsilateral Stroke/SAH or Death Due to Neurologic Cause Within Six (6) Months After Treatment., measured over 6 months.

The primary endpoint is the percentage of successfully implanted participants who experienced major ipsilateral stroke or SAH, or death due to a neurologic cause, within 6 months after treatment. It combines serious neurological events into a safety measure focused on the treated side and on neurologic death. The registry describes the outcome as a count of participants, but does not post a count or percentage for this endpoint.

As a general statistical point, a composite endpoint can capture several clinically important event types in a single measure. This may make the measure useful for describing a broad safety question, but it also means the overall result depends on which component events occurred. Component-specific counts help readers understand what contributes to a composite. The registry record does not report component results for the primary endpoint.

The endpoint is used to assess safety after device placement, not to establish a comparative treatment effect. The study has no comparator group. Its description states that all neurological events were adjudicated by an independent Medical Monitor, which indicates a specified review process for neurological events. The registry record does not provide further adjudication procedures or the primary endpoint result, so its frequency and precision cannot be assessed from the posted record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The study is a single-group, prospective evaluation. In general, a single-group study describes outcomes among participants receiving the intervention. Without a concurrent comparator, it cannot separate outcomes associated with treatment from outcomes that might have occurred under another strategy. This is a limitation of the design for comparative inference, not a statement about whether any particular event was caused by the device.

What does the primary outcome count?

The primary outcome is framed as a percentage of participants who experienced a specified neurological event within 6 months after treatment. Its components are major ipsilateral stroke, SAH, or death due to a neurologic cause. The outcome description says that all neurological events were adjudicated by an independent Medical Monitor. For a binary outcome, the basic descriptive information is the number of participants with the event and the number assessed in the relevant population. The registry record does not report those primary-outcome counts, the resulting percentage, or an uncertainty interval.

A confidence interval is a general statistical tool for expressing uncertainty around an estimate. It helps readers distinguish a relatively precise estimate from one that remains compatible with a broad range of values. Its width depends on the amount and pattern of information available, among other factors. Since the registry record does not post the primary estimate or its interval, the endpoint’s precision cannot be evaluated from this record. No p-value or inferential analysis for the primary outcome is listed either.

Why does the absence of a comparator matter?

With a comparator, a trial may estimate a difference between groups under its specified design and analysis. This registry record lists no comparator and no random allocation. Therefore, a count of events in the treated group would describe that group; it would not by itself quantify how the outcomes compare with another intervention. Observational counts can be informative about what was recorded, but they do not provide the protections against confounding that random allocation can offer.

Masking is listed as NONE. In general, masking can reduce the influence of knowledge about treatment assignment on certain assessments or decisions. The registry does not describe masked assessment, and it does not give additional details about how the independent Medical Monitor’s adjudication was conducted. The stated adjudication process should therefore be reported as described, without assuming procedures beyond the record.

How should planning illustrations be understood?

The registry’s sample-size assumptions describe a planning illustration computed from the observed effect, not the trial’s own design. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. The record says that time-to-event entries use the total number of events, while other entries use participants per arm. These are planning assumptions, not evidence that this single-group pilot used a two-arm design. They do not turn the observed study into a randomized comparison.

In general, sample-size planning asks how much information a proposed study might need under specified assumptions. An illustration based on an observed effect is conditional on that effect and on the planning choices; it is not an observed property of the trial and is not observed power. The registry record does not report the study’s own sample-size justification or design calculations. No numerical planning output is stated in the record, so none can be used to infer the trial’s planned or achieved precision.

The record lists 2 outcome measures and 0 analyses. That means the registry entries available for analysis do not include a posted statistical analysis for the primary endpoint. It does not establish what analyses may have been planned or conducted outside the record. The statistical plan, including any adjustment strategy, model choice, or approach to sparse events, is not reported in the registry record.

As a general point, binary outcome analyses depend on the event count and the number of participants with outcome information. When counts are limited, estimates may be imprecise, and conventional approximations may perform poorly. The record does not provide enough primary-outcome information to assess those issues for this endpoint. No recalculated primary estimate or inferential result can be derived from the information posted.

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("Treated")
n      <- c(19)
events <- c(0)
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  Treated  19  0  0.0  0.0  17.6  0.0  16.8  0.1  16.8

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures: the primary neurological safety endpoint and the secondary outcome Occlusion Status of the Target IA. It lists 0 analyses. The registry record does not report a multiplicity plan, such as whether the outcomes were to be tested in a particular order or whether any adjustment was planned. Without an analysis plan and posted outcome results, it is not possible to assess how multiple outcomes were handled or how any inferential findings should be interpreted.

The primary endpoint population is described as patients who were successfully implanted with the Contour device. The record does not report how many participants were successfully implanted, how many had outcome data available at 6 months, or how participants without outcome information were handled. A missing-data approach, including any imputation or sensitivity analysis, is not reported in the registry record. The absence of those details means that the completeness of primary endpoint follow-up cannot be evaluated from the posted record.

The registry does not report the analysis population definitions beyond the stated primary population. It does not explain whether all enrolled participants, only successfully implanted participants, or another population was used for any analysis. Since no analyses are listed, there is no posted account of exclusions, protocol deviations, or analysis-specific denominators. These omissions limit assessment of both the outcome population and the possible effect of missing information.

In general, multiplicity concerns arise when several outcomes or comparisons are assessed, because the chance of finding an apparently notable result can depend on how many analyses are performed and how they are interpreted. Missing-data methods matter because the available participants may not represent those without recorded outcomes. Those are general considerations; the registry does not provide enough analysis detail to determine how either issue was addressed in this study.

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: other - unrelated to device or procedure (10.5%), transient ischemic attack (5.3%), device deployment issue (5.3%).

The treated-group adverse-event summary lists 19 participants at risk, with 4 affected in the serious category and 10 affected in the other category. It also lists 0 deaths. These are participant counts as recorded in the adverse-event summary; they are not a posted result for the primary endpoint. The record does not describe whether the serious and other categories overlap, so the counts should not be combined or treated as mutually exclusive.

The serious-term entries are Other - Unrelated to device or procedure at 10.5%, Transient Ischemic Attack at 5.3%, and Device deployment issue at 5.3%. They provide additional descriptions of reported serious terms, but they do not supply the primary endpoint’s event count or clarify which primary endpoint components occurred. The listing also does not give enough information to infer a causal relationship for terms other than the registry’s stated classification.

Adverse-event counts need their category definitions, follow-up context, and denominators for interpretation. The registry record does not provide further detail about event timing or the relationship between these summaries and the primary endpoint follow-up. These figures describe what the record lists; they should not be read as proof of safety or harm, or as a comparison with another treatment.

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

The record establishes that the study was designed to evaluate the safety and performance of the Contour Neurovascular System in intracranial aneurysm treatment. It specifies a primary safety question concerning major ipsilateral stroke or SAH, or neurologic death, within 6 months after treatment among patients successfully implanted with the device. It also identifies Occlusion Status of the Target IA as a secondary outcome. Those definitions clarify what the study set out to examine.

The posted record does not report the primary endpoint result or a result for the secondary outcome. It therefore does not show the observed frequency of the primary endpoint, whether any particular component occurred, or how precisely an endpoint estimate was measured. The adverse-event entries offer selected counts and serious-term listings, but they cannot substitute for the missing primary result. The record also does not report the analysis population size for that endpoint.

The single-group design does not provide a control-based estimate of how outcomes compare with another intervention. Even if a group-level outcome result were posted, a result from this design would describe the treated group and would not, by itself, establish what would have happened under a different treatment strategy. The record also does not report the reason for termination, so the study status should not be interpreted as evidence for a particular safety or efficacy conclusion.

In general, a clinical trial result is interpreted in light of its outcome definition, observed data, uncertainty, analysis population, and design. Here, the registry supplies the endpoint definition and design features, plus selected adverse-event summaries, but not the primary result or inferential analysis. The appropriate conclusion is limited: the registry documents the study’s question and some safety reporting, while leaving the principal outcome and comparative implications unresolved.

14. Why This Trial Matters Statistically

This study matters statistically because it illustrates the difference between an outcome definition and an outcome result. The registry clearly specifies a primary safety endpoint and a follow-up window of 6 months, but does not post the endpoint estimate. Without the event count, denominator, or uncertainty measure for that endpoint, readers cannot assess its observed frequency or precision. Detailed outcome definitions are useful, but they do not replace the data needed to interpret results.

The design also makes the scope of inference important. This is a prospective, single-group study with allocation listed as NA and masking as NONE. Its observations can describe what was recorded among treated participants, but the absence of a comparator means there is no direct treatment contrast. That distinction matters when reading safety summaries: event counts are descriptive evidence, not a comparative estimate.

The registry’s sample-size assumptions are described as planning illustrations based on an observed effect and a hypothetical two-arm allocation. This is distinct from the actual single-group design. The difference reinforces why planning calculations should not be mistaken for a record of what the trial planned, achieved, or could detect. The study’s own sample-size justification is not reported in the registry record.

Finally, the record lists 2 outcomes and 0 analyses, while the study status is TERMINATED and the reason is not reported. These features make transparent reporting of outcome results, analysis populations, missing data, and multiplicity especially important for interpretation. The record demonstrates how registry entries can preserve useful design information while still leaving key statistical questions unanswered.

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 registry record gives limited information about the study beyond its broad design, intervention, outcomes, and selected adverse-event summaries. It identifies the study as prospective, single arm, and multi centre, but does not report site details, eligibility criteria, recruitment information, or the number of participants successfully implanted. Enrollment of 20 should not be treated as the denominator for the primary endpoint because that endpoint is defined for successfully implanted patients and its analysis population is not reported.

The most important limitation for interpretation is that the primary outcome result is absent. The record does not provide the count or percentage of participants with the composite endpoint, a component breakdown, or an uncertainty estimate. It also does not post a result for the secondary occlusion outcome. The listed adverse-event information is not enough to reconstruct those results.

Other relevant details are not reported in the registry record: the reason for termination, the trial’s own sample-size justification, the statistical analysis plan, multiplicity handling, missing-data methods, and analysis-specific population definitions. The record does not explain follow-up completeness for the primary endpoint or whether adverse-event categories overlap. These gaps limit assessment of outcome completeness and the methods used to analyze the data.

The single-group design additionally limits comparative interpretation, and masking is listed as NONE. The registry’s description of independent Medical Monitor adjudication is useful, but the adjudication procedures are not otherwise detailed. These are limitations of what can be assessed from the registry record; they do not establish that unreported procedures or analyses were absent outside it.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Pilot Study of the Contour Neurovascular SystemTM — NCT02784431.
• Registry record last updated 2022-07-26; status last verified 2022-07.
• Results first posted 2021-06-23.
• 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

NCT02784431 is a prospective, single-arm, multi centre pilot study of Contour Neurovascular System placement for intracranial aneurysm. The registry lists enrollment of 20, a start date of 2016-07, primary completion of 2018-10, and status TERMINATED. Allocation is NA and masking is NONE.

The primary endpoint is the percentage of successfully implanted participants with major ipsilateral stroke or SAH, or death due to a neurologic cause, within 6 months after treatment. Occlusion Status of the Target IA is listed as a secondary outcome. The registry lists 2 outcome measures and 0 analyses.

The treated-group adverse-event summary lists 19 participants at risk, 4 affected in the serious category, 10 affected in the other category, and 0 deaths. The primary endpoint result, secondary outcome result, reason for termination, and key analysis details are not reported in the registry record. The absence of a comparator means the study record does not provide a controlled treatment comparison.