Vesalio NeVa VS for Symptomatic Cerebral Vasospasm Following aSAH (The VITAL Study): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Vesalio NeVa VS for Symptomatic Cerebral Vasospasm Following aSAH (The VITAL Study) (NCT03611790), a na na study. The primary outcome is Procedural Success.

2. Clinical Question

This clinical question has two distinct parts: whether the procedure met the stated imaging criterion, and what safety events were recorded. The registry describes procedural success as the primary outcome and gives adverse-event figures for the single intervention group. Those descriptions do not, on their own, establish how the device’s outcomes compare with outcomes under another approach. The registry’s stated objective includes safety and probable benefit, but it does not report a comparative estimate of benefit.

3. Trial Design

The VITAL Study is recorded as a completed, single-group study of the NeVa VS device in symptomatic cerebral vasospasm following aSAH. The registry lists enrollment of 30 and identifies the intervention as a device. The study began on 2018-12-19, reached primary completion on 2021-05-31, and has completed status. Its phase is listed as NA.

A single-group design means that the posted results describe participants receiving the intervention, rather than contrasting outcomes between randomized treatment groups. Allocation is listed as NA, and the study is recorded as having no masking. A control group, a randomized comparison, and a masked comparison are not described in the registry record. The record therefore does not support interpreting an observed outcome as an estimate of the difference between NeVa VS and an alternative.

The primary outcome is a count of vessels treated that met a specified procedural criterion. The outcome is measured at the vessel level, while enrollment is recorded for the study. The registry does not report how many vessels were treated, how vessel observations were distributed across participants, or how repeated vessel observations were handled in analysis. Those details matter when interpreting a vessel-level count because observations from the same participant may not be statistically independent.

The registry says the study data were analyzed using descriptive statistics due to the small sample size (N=30). It does not report a detailed statistical analysis plan, a sample-size justification, or registered analysis records. Although the study status is completed, completion alone does not fill in those methodological details or establish that a particular inferential analysis was conducted.

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: The VITAL study data were analyzed using descriptive statistics due to the small sample size (N=30).

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 Procedural Success, measured over within 30 minutes of completion of procedure.

The primary endpoint is “Procedural Success,” measured as a count of vessels treated. A vessel met the definition if its caliber on DSA was 50% or greater compared with baseline, as determined by the core laboratory, within 30 minutes of completion of the procedure. The definition specifies an imaging modality, a baseline reference, a threshold, an assessor, and a time window. These features make the endpoint more operational than a general judgment that a procedure was successful.

An immediate imaging endpoint can describe whether the intended vessel-caliber criterion was observed around the time of the procedure. It is not, by itself, a measure of later clinical status, quality of life, or sustained vessel response. The registry’s description does not state that those outcomes are part of this primary endpoint. Nor does the endpoint definition establish that meeting the imaging criterion caused a later clinical benefit.

Counting vessels rather than reporting a participant-level outcome raises an interpretive distinction: one participant could potentially contribute more than one vessel observation, but the registry record does not say whether that occurred or how such observations were summarized. A vessel count also needs a clearly described denominator to show the proportion meeting the criterion; that denominator and the observed primary result are not reported in the registry record. The endpoint’s intended definition is stated, but its result and precision cannot be assessed from the registry information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the study’s analysis as descriptive statistics because of the small sample size (N=30). Descriptive statistics report the observed data in an organized form, such as counts or summaries. They can help characterize what happened in the enrolled group. They do not automatically answer a causal question or estimate how outcomes would differ under an alternative intervention. That distinction is especially important in a single-group study, where no concurrent control group is listed.

What does a vessel count represent?

The primary endpoint is a count of vessels treated that met the stated success definition. The endpoint is not described as a participant-level proportion or a time-to-event outcome. To interpret a count, readers need to know both the number meeting the criterion and the number of vessels assessed. The registry record does not report either the primary count or its denominator. Enrollment of 30 refers to the study, but it does not establish the number of treated vessels.

Vessel-level observations may also be related when more than one vessel is assessed in the same participant. General statistical explanation: correlated observations contain less independent information than the same number of unrelated observations. An analysis that treats related observations as independent can give uncertainty estimates that are too narrow. The registry record does not say whether participants contributed multiple vessel observations or describe any method for accounting for dependence. It is therefore not possible to assess how this issue was handled.

Why does uncertainty matter?

A point estimate, when reported, describes the observed result in the study. An uncertainty interval gives additional information about how precisely that result is estimated under a statistical method. General explanation: wider intervals indicate less precision, while narrower intervals indicate greater precision, all else being equal. The registry record does not report a confidence interval or another uncertainty estimate for the primary endpoint. Since the endpoint result itself is also not reported, its size and precision cannot be evaluated.

A small sample can make estimates imprecise, particularly for uncommon outcomes. The registry explicitly cites the small sample size as the reason for using descriptive statistics. That statement does not reveal the intended precision of the study, how enrollment was chosen, or whether the study was designed to test a formal hypothesis. A sample-size justification and the protocol’s statistical plan are not reported in the registry record.

How should a one-group result be interpreted?

In a randomized comparison, a treatment effect is generally estimated by comparing outcomes between groups, with the analysis reflecting the allocation and outcome structure. This study is recorded as single group, with allocation listed as NA and no masking. It does not provide a like-for-like control comparison. Consequently, descriptive outcomes in the intervention group cannot isolate the effect of the device from other influences, including the underlying condition, other care, or the course of events around the procedure. This is a general limitation of interpreting uncontrolled observations, not a claim about what caused any particular outcome in this study.

The registry’s stated objective was to assess safety and probable benefit. An objective is not itself a result. The record’s primary outcome definition gives a standardized criterion for procedural success, but does not report the number meeting it. The safety data offer counts and listed event terms, but the record does not provide a comparative analysis or causal attribution. Thus the methods description supports a limited, descriptive reading rather than an estimate of comparative effectiveness.

What do the planning illustrations mean?

Any planning illustrations associated with the posted results are not observed trial findings and are not the study’s own design justification. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is expressed as a stated fraction of the observed effect. For time-to-event calculations, the illustration is based on the total number of events; for other calculations, it is expressed as participants per arm. These are hypothetical planning assumptions, not evidence that this single-group study had a two-arm design.

Such illustrations can help explain how a future study’s planning requirements change when the target effect or desired power changes. They do not establish that the effect will recur, and they do not measure the probability that a treatment works. Sample-size illustrations are planning calculations, never observed power. The registry does not report its own sample-size rationale, and no planning illustration should be attributed to the VITAL Study’s original design unless that is stated in the registry record.

The registry lists no analysis records. This does not mean that no descriptive analysis was performed, because the outcome description explicitly says descriptive statistics were used. It does mean that a registered set of analysis entries is not available in the record to clarify analysis choices. Details such as the exact summary measure, treatment of missing outcome data, assumptions for inferential testing, and any sensitivity analyses are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome measure and no analysis records. It does not report a multiplicity adjustment or a strategy for controlling the chance of false-positive findings across multiple outcomes or analyses. General statistical explanation: when several hypotheses are tested, the chance of at least one apparently positive result can increase unless the analysis plan accounts for the multiplicity. That general concern cannot be quantified for this study from the registry record, and the record does not establish that multiple hypothesis tests were conducted.

Missing-data handling is not reported in the registry record. The entry does not state how many primary-endpoint observations were unavailable, whether any participants or vessels were excluded from an analysis, or how missing values were handled. The enrollment figure alone does not reveal completeness for a vessel-level endpoint. No imputation approach, complete-case rule, or sensitivity analysis is described.

The analysis population is also not reported in the registry record. It is not specified whether the primary outcome used all enrolled participants, all treated participants, all treated vessels, or another defined set. The endpoint is measured as a count of vessels, but the relationship between the vessel observations and participant-level enrollment is not described. Without that information, readers cannot determine the analysis denominator or whether all eligible observations contributed.

These omissions limit reproducibility and make it harder to assess selection and uncertainty. They do not prove that data were missing or that analyses were selectively reported; the registry record simply does not provide those details. The stated use of descriptive statistics is the available analysis description.

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: cerebral infarct secondary to vasospasm (10.0%), anemia (10.0%), intraprocedural thrombotic event (6.7%), cerebral infarct (3.3%), pseudoaneurysm of the contralateral femoral artery (3.3%).

The registry reports 17 participants affected by serious adverse events among 30 at risk, and 25 affected by other adverse events among 30 at risk. It also lists 7 deaths. The record does not give a comparative group, so these figures describe the single intervention group and should not be read as estimates of excess risk relative to another treatment.

The listed serious adverse-event terms are cerebral infarct secondary to vasospasm at 10.0%, anemia at 10.0%, intraprocedural thrombotic event at 6.7%, cerebral infarct at 3.3%, pseudoaneurysm of the contralateral femoral artery at 3.3%, and ruptured vessel due to balloon angioplasty at 3.3%. These are event-term percentages in the registry record. The record does not provide further detail about timing, severity grading, overlap among terms, or causal attribution. The categories should not be added together: the registry does not state whether a participant could have more than one event or appear under more than one term.

General statistical explanation: adverse-event counts describe what was recorded during the study, while interpretation of treatment-related risk requires attention to event definitions, follow-up, comparison groups, and possible overlap. The registry record does not report enough detail to resolve those issues. The figures warrant descriptive reading, not a conclusion that the device caused or prevented a particular event.

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

The VITAL Study record establishes that a completed, single-group study of NeVa VS was conducted in patients with symptomatic cerebral vasospasm following aSAH. It states the study objective, the primary endpoint definition, the descriptive nature of the analysis, and several adverse-event figures. It does not report the observed primary endpoint result. Accordingly, the record does not allow readers to determine how many treated vessels met the procedural-success criterion or how precisely that result was estimated.

The study’s single-group design also limits what can be learned about comparative effects. Without a control group, an outcome observed after treatment cannot be separated from other possible influences through a direct between-group comparison. This does not erase the descriptive information, but it changes what that information can support. The registry’s objective refers to safety and probable benefit; the stated objective should not be mistaken for evidence of a particular benefit.

The safety counts and serious-event terms describe events recorded in the intervention group. They do not, on their own, establish causation. The registry does not provide a comparator or causal attribution, and details about event timing, overlap, and analysis populations are not reported in the registry record. Likewise, the listed deaths are a descriptive count, not a comparative estimate.

General statistical explanation: a result can be clinically important yet uncertain, and a precise estimate can still be limited by study design. For this record, the absence of a reported primary result prevents assessment of its magnitude or precision, while the lack of a comparison group prevents a direct estimate of how outcomes differ from an alternative. Neither limitation should be replaced by assumptions about unreported results.

The study can therefore be understood as a descriptive record of a device intervention with a defined immediate imaging endpoint and reported safety information. It does not establish a comparative treatment effect, and the registry record does not provide the primary endpoint finding needed to judge the observed procedural-success result.

13. Why This Trial Matters Statistically

This study raises a useful statistical distinction between a clearly defined outcome and a fully interpretable result. The primary endpoint specifies what counted as procedural success: vessel caliber on DSA compared with baseline, judged by the core laboratory, within 30 minutes of procedure completion. Clear operational definitions reduce ambiguity about what an outcome is intended to capture. But a definition alone is not an estimate; the registry record does not report the number of vessels meeting the criterion or its denominator.

The endpoint is recorded as a vessel count, while enrollment is given at the study level. This makes the unit of analysis important. If participants contribute multiple vessel observations, those observations may be related. General statistical explanation: methods for clustered data account for such within-participant dependence, which can affect uncertainty estimates. The registry record does not describe the number of vessels assessed per participant or how any dependence was handled.

The study also illustrates why descriptive safety figures and comparative evidence answer different questions. Counts of serious events, other events, and deaths convey what was recorded in the treated group. Without a control group, they do not establish how those outcomes compare with another approach. The single-group design is therefore central to interpretation, not a minor technical detail.

Finally, the registry’s statement that descriptive statistics were used due to the small sample size (N=30) identifies a broad analysis approach, but it does not replace a detailed statistical plan. The record does not report the primary outcome result, an uncertainty estimate, missing-data methods, or analysis-population rules. These omissions limit precision and reproducibility. The statistical importance of the study lies in reading its endpoint definition and safety descriptions within the boundaries of the available design and reporting.

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 the main outcome is that the observed procedural-success result is not reported in the registry record. The definition and assessment window are stated, but the count of successful vessels, the number assessed, and an uncertainty estimate are absent. This prevents evaluation of the endpoint’s magnitude and precision.

The single-group design provides no like-for-like control comparison. Allocation is listed as NA, and masking is listed as none. Descriptive findings cannot establish how outcomes would have differed under another treatment or without the device. The registry’s stated objective to assess safety and probable benefit does not resolve that design limitation.

The vessel-level endpoint creates a further interpretive question because the registry does not report how many vessels were assessed or whether a participant could contribute multiple vessels. It also does not explain how such observations were handled statistically. The analysis population, missing-data approach, and any sensitivity analyses are not reported in the registry record.

Safety reporting is likewise limited by the absence of a comparison group and by unreported details about event timing, overlap, and causality. The listed adverse-event figures remain descriptive. The record also does not report a detailed analysis plan, sample-size justification, or registered analysis entries. These gaps limit assessment of reproducibility and of the intended inferential framework; they do not establish that any particular analysis was or was not performed beyond the stated use of descriptive statistics.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Vesalio NeVa VS for Symptomatic Cerebral Vasospasm Following aSAH (The VITAL Study) — NCT03611790.
• Registry record last updated 2023-01-03; status last verified 2022-12.
• Results first posted 2023-01-03.
• 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

The VITAL Study (NCT03611790) is recorded as a completed, single-group study of the NeVa VS device for symptomatic cerebral vasospasm following aSAH. Enrollment was 30. The study began on 2018-12-19 and reached primary completion on 2021-05-31. Phase is listed as NA, allocation as NA, and masking as none.

The primary outcome was a count of vessels meeting a DSA-based procedural-success definition within 30 minutes of procedure completion. Success required vessel caliber 50% or greater compared with baseline, as determined by the core laboratory. The registry states that descriptive statistics were used due to the small sample size (N=30), but the primary outcome result is not reported.

Safety information lists 17 participants with serious adverse events among 30 at risk, 25 with other adverse events among 30 at risk, and 7 deaths. The record provides no control group, and the figures do not establish causation or comparative risk. Missing-data handling, analysis populations, and a detailed statistical plan are not reported in the registry record.