Coil Assisted Flow Diversion Safety and Performance Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Coil Assisted Flow Diversion Safety and Performance Study (NCT04187573), a na na study. The primary outcome is The Proportion of Subjects With Death of Any Non-accidental Cause or Any Major Disabling Stroke After Treatment or Major Disabling Stroke or Death Due to Neurological Cause..

2. Clinical Question

3. Trial Design

CAFI is identified as a prospective, single-arm, multi-center study sponsored by Cerus Endovascular, Inc. Its full study title describes an assessment of Neqstent in adjunctive therapy. The condition recorded is intracranial aneurysm, and the intervention is the Neqstent device. The registry lists the study phase as NA, allocation as NA, masking as none, and model as single group. The study status is completed.

The record lists enrollment of 38. The study start date is 2020-01-21, and the primary completion date is 2022-06-17. Those entries describe the registry record; they do not, on their own, establish the number included in the primary endpoint analysis or the length of follow-up for every participant.

With no randomized allocation and no comparator arm, the design is suited to documenting observed outcomes among participants treated in the study, but it does not estimate a randomized contrast against another intervention or usual care. Outcomes may be described within the treated group, but differences from an external population cannot be attributed to the device based on this design alone. The registry record does not report details of the number or locations of centers, the enrollment process, eligibility criteria beyond the stated primary population definition, or a separate protocol-level statistical plan.

The primary endpoint has a stated observation window from day 31 to 6 months after treatment. The record also lists two outcome measures, but reports zero analyses. In particular, a primary endpoint result is not included in the posted material. The adverse-event entries provide descriptive safety information, but they do not substitute for the missing primary endpoint result.

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

Analysis population for the primary outcome, as defined in the registry: Intent-to-treat: All eligible subjects who underwent an attempt with the Neqstent 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.

Population: All patients; 38 patients were listed in the Participant Flow, and all 38 patients were included in the population description.

6. Primary Endpoint

The registry lists the primary outcome as The Proportion of Subjects With Death of Any Non-accidental Cause or Any Major Disabling Stroke After Treatment or Major Disabling Stroke or Death Due to Neurological Cause., measured over From day 31 to 6 months after treatment.

The primary endpoint is a composite safety outcome involving death and major disabling stroke. Its title includes death of any non-accidental cause or any major disabling stroke after treatment, or major disabling stroke or death due to a neurological cause. The stated timeframe is from day 31 to 6 months after treatment. The population is described as all eligible subjects who underwent an attempt with the Neqstent device.

A composite endpoint combines multiple clinical events into one outcome. General rationale: combining events can capture more than one important type of harm in a single measure, while ensuring that the definition and observation window are explicit. Interpretation depends on which events qualify, how they are ascertained, and whether the component events have comparable clinical importance. The registry record does not provide component-specific results or further definitions of major disabling stroke.

The measure is listed as a count of participants, even though the endpoint title refers to a proportion. A count gives the number meeting the endpoint definition; a proportion also requires a denominator, such as the number of participants assessed in the defined population. The record does not post the endpoint count, denominator, or proportion. Enrollment of 38 is not identified as the endpoint denominator. Consequently, neither the observed frequency nor its statistical precision can be assessed from this outcome entry.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry classifies the primary outcome as binary in kind, with the measure expressed as a count of participants. In practical terms, each participant either meets the stated composite definition during the specified window or does not. A count of participants meeting the definition can then be used to describe the observed occurrence in a defined group. To interpret that occurrence as a proportion, the denominator must also be known and must match the population and follow-up rules.

What does a count-based binary endpoint mean?

General explanation: binary outcomes classify each observation into one of two categories, such as event or no event. A participant count is the number in the event category. For a proportion, the count is considered relative to the eligible population assessed. That denominator matters because the same count can imply different frequencies in groups of different sizes. Here, the registry identifies an intent-to-treat population as all eligible subjects who underwent an attempt with Neqstent, but it does not post the number in that population or the primary endpoint count. Enrollment is recorded as 38; it should not be substituted for the endpoint denominator without an explicit link in the record.

Why is the endpoint composite?

The endpoint groups specified death and major disabling stroke outcomes. General explanation: composite endpoints can combine several clinically important events into a single endpoint, potentially capturing a broader range of outcomes than any one component alone. The trade-off is that a total composite result can conceal how much each component contributes. Component counts and definitions are useful for interpreting the result, especially when components differ in severity or frequency. The registry record does not report component-specific results or details beyond the endpoint title.

How should the timeframe be read?

The stated timeframe is from day 31 to 6 months after treatment. This defines the period identified for the primary measure; it is not the same as a complete description of every participant's follow-up. The record does not say how deaths or strokes outside that window were handled for this endpoint, whether participants with incomplete follow-up were included in a particular way, or how the endpoint events were adjudicated. Those details are not reported in the registry record.

What can a confidence interval contribute?

General explanation: a confidence interval accompanies an estimate to express statistical uncertainty arising from the observed data, given the chosen method and its assumptions. A narrower interval generally indicates greater precision than a wider interval, but interval width does not resolve possible bias, incomplete follow-up, or limitations of the design. No primary endpoint estimate or confidence interval is posted, so neither the magnitude nor precision of the primary outcome can be assessed.

Why does the single-arm design matter?

General explanation: an observed event frequency in one treated group is descriptive. A comparison group can help estimate how outcomes differ between treatment strategies, although interpretation still depends on design and analysis. In a non-randomized, single-arm study, differences from other populations may reflect differences in participant characteristics, care, follow-up, or outcome recording rather than the intervention. CAFI is recorded as a single group, with allocation listed as NA and masking as none. The record therefore does not provide a randomized treatment contrast.

What do the adverse-event percentages represent?

The registry lists serious adverse-event terms with percentages, including Stroke at 18.9% and Non-index Aneurysm Treatment at 5.4%. Other listed terms are each reported at 2.7%. These are the values recorded for the listed terms; the record does not describe the calculation denominator or whether a participant could contribute to multiple terms. General explanation: adverse-event summaries may count participants, events, or coded terms, and those quantities are not interchangeable. The registry's reported percentages should therefore be interpreted as its listed descriptive values, not recalculated into a different measure.

What cannot be inferred from the record?

No analysis result is posted for the primary endpoint, and no statistical analysis details are included in the record. The record does not report a model, adjustment strategy, hypothesis-testing procedure, interim-analysis plan, handling of missing endpoint observations, or a sample-size justification. These omissions prevent assessment of how the primary outcome would have been estimated or tested. General methodological concepts can describe what such choices mean, but cannot establish which choices were made for this study.

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("Intervention/Neqstent")
n      <- c(37)
events <- c(2)
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  Intervention/Neqstent  37  2  5.4  0.7  18.2  1.5  17.7  1.7  17.7

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures and zero analyses. It does not describe a statistical plan for the primary endpoint or other outcomes, so the analysis hierarchy and any distinction between confirmatory and descriptive outcomes are not reported in the registry record.

Multiplicity arises when several hypotheses or outcomes are examined. General explanation: testing multiple outcomes can increase the chance of at least one apparently notable result if each is assessed separately. A prespecified hierarchy or adjustment can address some multiplicity concerns, but the choice depends on the study objectives and plan. The record does not report whether any multiplicity strategy was specified or used. Since no endpoint analysis is posted, there are no registry-reported hypothesis tests to interpret.

The intent-to-treat population is described as all eligible subjects who underwent an attempt with Neqstent. The record does not state how missing outcome assessments, incomplete follow-up, withdrawals, or participants without sufficient information for endpoint classification were handled. It also does not provide the size of the defined primary analysis population. General explanation: missing observations can affect an estimate when participants with missing data differ in outcome risk from those observed, and analysis choices can influence the result. Without a reported approach and participant flow, the impact cannot be assessed.

The record does not report interim analyses, a sample-size justification, or details of the statistical analysis plan. Their presence or absence in the actual study conduct cannot be inferred from the registry entries; the relevant information is not reported in the registry record.

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: stroke (18.9%), non-index aneurysm treatment (5.4%), aneurysm reccurence (2.7%), headache (2.7%), depression (2.7%).

The adverse-event summary lists 37 participants at risk in the Neqstent group. It records 15 participants affected by serious adverse events, 19 affected by other adverse events, and 1 death. These entries are descriptive counts in the registry. They do not establish that the categories are mutually exclusive, so the counts should not be added together or treated as distinct groups of participants.

Listed serious-event terms include Stroke at 18.9%, Non-index Aneurysm Treatment at 5.4%, and Aneurysm Reccurence, Headache, Depression, and Shoulder Injury at 2.7% each. The record does not provide the underlying counts for each listed percentage, explain whether terms represent participants or events, or state whether one participant could appear under multiple terms. The percentages should therefore be read as the registry's reported values rather than converted into counts.

The one recorded death cannot be directly equated with a primary endpoint event from the information posted. The primary endpoint has a specific composite definition and a specified timeframe, and the record does not state whether this death met those criteria. Nor does the single-arm design permit a comparison of adverse-event frequencies against an untreated or alternative-treatment group. These safety entries describe what the registry reports; they do not by themselves establish causation or comparative risk.

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

The record establishes that CAFI was a prospective, multi-center, single-arm study intended to document safety and performance of Neqstent in adjunctive therapy for intracranial aneurysm treatment. It gives an enrollment entry of 38 and a primary safety endpoint focused on death and major disabling stroke during the stated period from day 31 to 6 months after treatment. It also posts descriptive adverse-event information for the Neqstent group.

What the record does not establish is the observed result for the primary endpoint. No count, proportion, or statistical analysis is posted for it. The endpoint's stated intent-to-treat population is not accompanied by a reported denominator, and the enrollment entry cannot be assumed to equal that population. The primary safety question therefore remains unresolved by the posted endpoint information.

The adverse-event counts and term percentages should be interpreted as registry descriptions, not as proof that Neqstent caused the events or that the device changed their likelihood. In general, events occurring after treatment are not necessarily caused by the treatment. Assessing comparative safety typically requires a suitable comparison and clearly defined event ascertainment. This study is recorded as single group and has no concurrent comparator.

Nor does the record show that the treatment is more or less effective or safe than another approach. There is no comparative estimate, and the primary endpoint result is not posted. The study's stated purpose and design can be described, but the available information does not support a conclusion about treatment benefit, lack of benefit, or comparative safety. The distinction between an absent result and a result showing no events is important: the registry record reports no primary endpoint result, not a zero-event result.

General interpretation: precision concerns how narrowly an estimate is determined by the data, while validity also depends on the design, measurement, and completeness of follow-up. Here, precision cannot be evaluated for the main endpoint because its estimate and interval are not reported. The single-arm design separately limits causal and comparative interpretation, even if descriptive outcome values are available.

14. Why This Trial Matters Statistically

This study is statistically notable because its principal question is framed as a clinically consequential composite endpoint, while the registry record does not post the endpoint result. That distinction illustrates why a clearly named outcome and timeframe are not sufficient for interpretation: readers also need an observed result, a denominator tied to the population definition, and information about uncertainty.

The design also matters. CAFI is listed as a prospective, multi-center, single-arm study with no masking and no randomized allocation. Such a design can describe what happened among participants treated in the study, but it does not produce a randomized comparison against another approach. The absence of a comparator limits what can be concluded about differences attributable to the device.

The record reports adverse-event counts and term percentages, which can inform a descriptive account of recorded events. However, event definitions, overlap between categories, and the relation of the recorded death to the primary outcome are not detailed in the posted information. Those gaps demonstrate why summary counts require context before they can be treated as estimates of a particular risk.

More broadly, the registry illustrates the difference between study completion and availability of analyzable results. The study status is completed, but the record lists zero analyses and does not report the principal endpoint result. Statistical interpretation depends not only on design and endpoints, but also on transparent reporting of estimates, populations, and methods. Without those details, conclusions must remain limited to the study's stated purpose, design, and posted descriptive safety information.

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.

Several trial-specific limitations constrain interpretation. First, the primary endpoint is not accompanied by an observed count or proportion, even though the record describes its definition, timeframe, and intended population. The record also does not give the denominator for that population. Thus, the primary safety outcome cannot be quantified from the posted endpoint information.

Second, the study is single arm, with allocation listed as NA and masking listed as none. There is no concurrent comparison group in the record. Observed outcomes therefore cannot establish how results compare with another treatment strategy or isolate a treatment effect. This remains true even if adverse-event counts are available.

Third, enrollment is recorded as 38, while the adverse-event group lists 37 at risk. The record does not explain the difference, and it does not identify either value as the primary endpoint denominator. The participant flow and analysis population size are not reported in the registry record.

Fourth, the adverse-event summary does not clarify whether affected-participant categories overlap, how listed term percentages were calculated, or whether the reported death meets the primary endpoint definition. Additional endpoint details, including component-specific results, event adjudication, and handling of incomplete follow-up, are not reported.

Finally, the record lists zero analyses and does not report the statistical plan, sample-size justification, multiplicity approach, missing-data method, or interim-analysis details. These omissions limit assessment of analytic choices and result precision. They should not be read as proof that a particular method was or was not used outside what the registry record reports.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Coil Assisted Flow Diversion Safety and Performance Study — NCT04187573.
• Registry record last updated 2024-11-20; status last verified 2024-10.
• Results first posted 2024-10-23.
• 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

CAFI is a completed, prospective, multi-center, single-arm study sponsored by Cerus Endovascular, Inc. It evaluated Neqstent as adjunctive therapy for patients with intracranial aneurysms. The record lists enrollment of 38, no masking, allocation as NA, and study phase as NA. The study start date is 2020-01-21, and the primary completion date is 2022-06-17.

The primary endpoint is a count of participants meeting a composite definition involving death and major disabling stroke, from day 31 to 6 months after treatment. Its defined population is all eligible subjects who underwent an attempt with Neqstent. The record lists two outcome measures and zero analyses; it does not post the primary endpoint result.

The adverse-event summary lists 37 at risk, 15 affected by serious events, 19 affected by other events, and 1 death. The record does not provide enough detail to resolve category overlap or connect the death to the primary endpoint. The single-arm design does not permit a randomized comparison.