Novel Helmet Design in Patients With Seizures: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Novel Helmet Design in Patients With Seizures (NCT03443388), a randomized na study. The primary outcome is Part 2: Helmet Deployment Questionnaire.

2. Clinical Question

3. Trial Design

The registry describes a randomized, unmasked study with a sequential model and classifies its phase as NA. Its title and summary identify it as a pilot study of the safety of a novel helmet design for people with seizures. The study is described as having two parts and evaluates the Hövding inflatable helmet, a device. The overall enrollment recorded is 9.

The Part 2 descriptions outline a helmet group and a no-helmet group. The helmet-group description says that, after screening, 10 patients with drug-resistant epilepsy would wear the helmet in daily life and complete questionnaires about seizures, injuries, and circumstances of inflation. The no-helmet description says that 10 subjects would initially not wear a helmet and would complete questionnaires about seizures and injuries, then cross over to the helmet group after approximately 3 months. These descriptions set out the planned arrangement; they do not establish how many participants actually entered or completed each group or condition. The discrepancy between the planned group descriptions and the recorded overall enrollment is not explained in the registry record.

The primary-outcome timeframe is 6 months. Other listed outcomes include the Rivermead Post Concussive Scale, a seizure questionnaire, injury-related medical-record review, and a helmet-deployment questionnaire covering seizure or non-seizure circumstances. The registry lists 6 outcome measures, but does not give a detailed schedule for each measure. It records no analyses. The statistical analysis plan, including the implementation of the sequential model, allocation procedures, and any handling of crossover data, is not reported in the registry record. Randomized allocation and lack of masking are registry classifications, not evidence about how participants or assessors experienced or followed the study procedures.

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 Part 2: Helmet Deployment Questionnaire, measured over 6 months.

The primary endpoint is the Part 2 Helmet Deployment Questionnaire. The registry describes it as comparing questionnaire responses for subjects wearing a helmet during a seizure with responses for subjects not wearing one during a seizure. The timeframe is 6 months. The study summary frames helmet deployment during seizures and qualitative patient reporting as evidence relevant to reliability and safety; the questionnaire therefore concerns the circumstances and reporting of helmet use, rather than a single continuous clinical measurement.

The endpoint description reports evaluable falls for 3 participants with the helmet and 2 participants without it. Only 1 patient had an evaluable fall in both conditions. This matters for interpretation because a comparison based on the same person's experience in both conditions relies on paired observations, and the registry describes very limited overlap. A comparison between different participants instead requires an appropriate between-participant analysis. The record does not state which approach was used, how questionnaire responses were summarized, or what the response categories were.

The endpoint is relevant to the study's stated question about deployment and reported circumstances, but its definition alone does not quantify deployment reliability, injury prevention, or safety. The registry record does not report the primary questionnaire response values, a comparative estimate, or an uncertainty interval. It is therefore possible to describe the endpoint and the evaluable-fall information, but not to infer the size or precision of a difference from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry labels the allocation as randomized, masking as none, and model as sequential. These labels describe broad design features, but do not supply the detailed procedures or analysis plan. In particular, the registry record does not report how the random sequence was generated, how assignments were concealed, what the sequential model means operationally, or how any crossover observations were handled. Those details should not be inferred from the labels alone.

What does randomization contribute?

In general, random assignment is intended to reduce systematic differences between comparison groups at the point of assignment. It does not guarantee that groups will be comparable in every small study, and it does not remove uncertainty caused by limited outcome information. Here, the primary-outcome description reports evaluable falls in both conditions for only 1 patient. The registry does not report the allocation sequence, baseline comparison, or analysis population, so the effect of randomization on the data available for the primary comparison cannot be assessed from the record.

How should the endpoint be analyzed?

In general, outcomes from different participants call for a between-participant comparison, while observations from the same participant in two conditions can be analyzed as paired data. Pairing accounts for the fact that measurements from one person may be related. The endpoint description identifies only 1 patient with an evaluable fall in both conditions, but does not state whether the primary analysis used paired or unpaired methods. Nor does it report the questionnaire categories, response coding, or the handling of participants with no evaluable fall. Since the outcome is described as differences in questionnaire responses, the chosen summary and test would depend on the response scale and analysis objective; neither is reported in the registry record.

Why does sparse information matter?

In general, a small amount of outcome information can make estimates unstable and uncertainty wide. For counts or binary outcomes, a small number of observed events may also limit the usefulness of approximations that work better with more data. For questionnaire responses with several categories, collapsing categories can discard information, while estimating separate category-specific effects can leave very little information in each category. The registry explicitly indicates that the primary outcome has several categories or time points and was not reduced to one comparison in the statistical summary. The category definitions and the analysis approach are not reported, so no particular model or test can be identified as the one used.

What do confidence intervals and p-values tell readers?

In general, a confidence interval describes the range of effect values reasonably compatible with the observed data under the model and assumptions used. Its width conveys precision; a narrow interval indicates greater precision than a wide one. A p-value describes how unusual data at least as extreme as those observed would be under a specified null model and assumptions. Neither quantity, by itself, describes clinical importance or corrects for a poorly defined outcome. The registry record does not report a confidence interval or p-value for the primary comparison, and it does not provide enough outcome detail to reconstruct either one.

How should planning calculations be read?

In general, a sample-size calculation depends on assumptions about the effect to detect, outcome variability or event frequency, significance level, allocation, and analysis method. The registry's planning assumptions describe an illustration based on an observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such planning illustrations are not observed power and do not establish what power the completed study achieved. They also cannot replace a reported result. The record does not give a study-specific justification for the planned enrollment or report that its planning assumptions were met.

The registry lists 0 analyses. This is a statement about the analyses listed in the record, not proof that no analyses were conducted. The statistical analysis plan, including any model for questionnaire responses, adjustments, treatment of repeated measures, and uncertainty estimation, is not reported in the registry record. Thus, the design labels and endpoint description allow readers to understand the broad question, but do not identify a reproducible analysis or support a reanalysis of the primary outcome.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 6 outcome measures and names secondary measures that include the Rivermead Post Concussive Scale, seizure questionnaire, injury-related medical-record review, and helmet-deployment questionnaire. It also notes that the primary outcome has several categories or time points and is not reduced to a single comparison in the statistical summary. When a study examines multiple outcomes, categories, or time points, the chance of observing an apparently notable result somewhere among them can increase. In general, a prespecified hierarchy or multiplicity adjustment can help address that issue. The registry record does not report such a strategy, the number of primary comparisons planned, or which analyses were designated as confirmatory.

The record lists 0 analyses, so it does not report analysis results for the primary or secondary outcomes. It also does not describe missing-data definitions, the amount or pattern of missing questionnaire information, or methods for handling missing responses. Evaluable-fall counts indicate that primary-endpoint information was available for some participants in each condition and that only 1 patient had an evaluable fall in both. They do not explain why other falls or responses were not evaluable, and they do not establish whether missingness was related to participant characteristics or outcomes.

The registry does not report the analysis populations, such as whether analyses included all randomized participants, only those who wore the helmet, or only those with evaluable falls. It also does not explain how crossover participation would be incorporated. Without these definitions, the target population represented by any primary estimate cannot be identified. These omissions limit assessment of multiplicity, missing-data assumptions, and the relationship between planned and analyzed participants; they should be treated as unreported details rather than filled in by assumption.

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 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports adverse events separately for Phase 1, Phase 2: Subjects Wearing a Helmet, and Phase 2: Subjects Not Wearing a Helmet. In Phase 1, the listed at-risk count is 4 for serious and other adverse events; 0 serious and 0 other events are recorded, and deaths are 0. For Phase 2 subjects wearing a helmet, the listed at-risk count is 5 for each event type; serious events are 0, other events are 0, and deaths are 0. For Phase 2 subjects not wearing a helmet, the listed at-risk count is 4 for each event type; serious events are 0, other events are 2, and deaths are 0.

These are registry counts, not rates or comparative risk estimates. They should be read within the listed groups and the record's limited enrollment, not generalized beyond them. The entries do not describe event types, severity details for the other events, timing, relatedness to the device, or duration of follow-up for each participant. The registry lists no serious adverse-event terms. Absence of a recorded serious event in these groups does not establish that serious events are impossible or that the device is safe for other people or circumstances. The adverse-event entries also do not answer the primary question about questionnaire responses and helmet deployment.

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

The registry record gives useful context for interpreting a pilot study: it identifies a randomized, unmasked design, a device intervention, a primary questionnaire endpoint, and a six-month timeframe. It also reports evaluable-fall information and adverse-event counts. These registry entries describe the study's scope and what information was recorded, but the primary comparison itself is not reported.

In particular, the evaluable-fall counts do not tell readers how often the helmet deployed, whether deployment occurred when intended, what participants reported in each questionnaire category, or whether injury outcomes differed between conditions. The record gives no estimated difference, uncertainty interval, or p-value for the primary endpoint. It therefore cannot support a quantitative conclusion about the magnitude or precision of a difference in questionnaire responses.

The safety entries show no serious adverse events or deaths recorded in the listed groups, and record 2 participants with other adverse events in the no-helmet group. These observations must be considered alongside the limited group sizes and incomplete information about event details and follow-up. They do not demonstrate absence of risk, and they are not a substitute for a complete safety analysis.

General statistical interpretation requires separating the question a study was designed to ask from the result that was actually reported. A randomized design can support a comparison when assignment, outcome ascertainment, and analysis are adequately documented, but the registry's broad design label alone cannot establish that all sources of bias were controlled. The crossover description is an intended arrangement, not proof that participants completed both conditions. Similarly, a planning illustration is not observed power and cannot stand in for an effect estimate.

The most defensible reading is that the registry specifies a pilot investigation of helmet deployment and patient reporting, while leaving the primary comparative result and key analysis details unreported. The findings recorded for safety are limited descriptive counts. The record does not establish whether the helmet improves outcomes, has no effect, or causes harm; those conclusions require reported comparative results and sufficient detail to assess their uncertainty and context.

13. Why This Trial Matters Statistically

This study raises a statistical challenge common to device research in episodic conditions: the outcome of interest may only be observed when a relevant event occurs. Here, the primary description concerns evaluable falls, and the registry reports few such observations across the helmet and no-helmet conditions. The distinction between participants assigned to a condition and participants with an evaluable event is important because the latter information directly constrains what can be learned about event-related deployment.

The described crossover arrangement also makes the analysis question consequential. When the same participant contributes observations in both conditions, a paired comparison can control for stable differences between people, but it depends on having observations in both conditions. When different participants contribute to each condition, a between-participant comparison is needed and may be more vulnerable to imbalance in a small study. The registry reports only 1 patient with an evaluable fall in both conditions and does not report which analysis was used. That makes transparent reporting of the analysis population and comparison method especially important.

The study also combines deployment, questionnaires, injury review, and other measures. These outcomes can answer different questions and may involve multiple categories or time points. Clear prespecification helps readers distinguish the main question from exploratory findings and interpret results without overemphasizing isolated comparisons. The registry's note that the primary outcome has several categories or time points, together with the absence of listed analyses, leaves that distinction unclear.

Finally, the safety counts illustrate why descriptive event reporting should include context, follow-up, and event detail. Counts in small groups can inform what was recorded, but they do not by themselves provide precise comparative safety estimates. For researchers, this record highlights the value of reporting the path from assignment through event eligibility, outcome capture, analysis, and uncertainty. That information is essential to understand what a pilot study can and cannot establish.

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 recorded overall enrollment is 9, while the Part 2 descriptions each refer to 10 planned subjects or patients. The registry record does not explain this difference or report the realized allocation by group. The descriptions also outline a crossover for the no-helmet group after approximately 3 months, but do not state how many people crossed over, completed both conditions, or contributed data in each period. As a result, the intended design cannot be assumed to match the completed study.

The primary endpoint is described as differences in questionnaire responses, but the response categories, scoring, direction of favorable response, and analysis method are not reported. The evaluable-fall information is sparse, and only 1 patient is reported to have evaluable falls in both conditions. The record does not explain why other falls were not evaluable or whether the questionnaire was completed after every relevant event. This makes it difficult to judge selection into the primary-outcome population.

The registry lists 6 outcome measures and no analyses. It does not report the statistical analysis plan, missing-data procedures, analysis populations, multiplicity strategy, effect estimates, confidence intervals, or p-values for the primary endpoint. The safety record also lacks event descriptions, timing, device relatedness, and detailed follow-up information. The registry's design labels do not fill these gaps. These limitations concern the information available in the registry record; they should not be interpreted as proof that the study team did not collect or analyze additional information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Novel Helmet Design in Patients With Seizures — NCT03443388.
• Registry record last updated 2025-01-09; status last verified 2025-01.
• Results first posted 2025-01-09.
• 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

NCT03443388 is a completed, randomized, unmasked pilot study titled Novel Helmet Design in Patients With Seizures. It evaluates the Hövding inflatable helmet in a two-part study described as examining reliability and safety through deployment during seizures and qualitative patient reporting. The registry records enrollment of 9 and a primary endpoint of Part 2: Helmet Deployment Questionnaire, with a 6-month timeframe.

The primary-outcome description reports evaluable falls for 3 participants with a helmet and 2 without one; only 1 patient had an evaluable fall in both conditions. The registry does not report comparative questionnaire results or a statistical analysis. Safety entries record no serious adverse events or deaths in the listed groups, and 2 participants with other adverse events in the Phase 2 no-helmet group. These descriptive records do not provide a comparative estimate or resolve the uncertainty around the primary endpoint.