This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Home Operations Utilizing Stimulation (NCT04484285), a randomized na study. The primary outcome is System Usability Scale.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04484285 |
| Phase | NA |
| Condition | Cognitive Performance |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 10 |
| Arms in the primary outcome | 2 |
| Lead sponsor | University of Florida |
| Results posted | Yes |
2. Clinical Question
Population
Healthy individuals in a younger cohort aged 18 - 55 and an older cohort aged 56 - 85. The registry lists an enrollment of 10.
Intervention
A home-operated transcutaneous vagal nerve stimulation (tVNS) device.
Comparator
The registry labels the Younger Cohort as the control, but does not describe a separate sham or untreated group. The reported outcome is organized by younger and older cohorts.
Primary question
What System Usability Scale scores were reported for the younger and older cohorts at Day 7?
The project is described as a proof of concept for home use of tVNS in healthy younger and older adults. Its stated rationale is that tVNS is believed to modulate cognitive performance; the registry’s primary endpoint, however, is usability rather than a direct measure of cognitive performance. The primary question that can be addressed from the posted outcome is therefore descriptive: what usability scores were recorded for the cohorts, and how much precision do those summaries support?
The record classifies the study as randomized, but does not report what was randomized or how randomization related to the age-defined cohorts. It also does not report a specific randomized comparator for the primary outcome. The registry describes a device intervention, but does not give enough detail to determine the stimulation schedule or establish whether the cohorts received the same protocol. These gaps limit any causal comparison between cohorts or attribution of a score to stimulation itself.
3. Trial Design
Home Operations Utilizing Stimulation is listed as a completed, randomized, parallel study with no masking. Its phase is recorded as NA. The sponsor is the University of Florida. The registry lists an enrollment of 10, a start date of 2020-08-20, and a primary completion date of 2023-09-06.
The population is divided into a Younger Cohort, described as healthy individuals aged 18 - 55, and an Older Cohort, described as healthy individuals aged 56 - 85. The intervention is a device named Transcutaneous Vagal Nerve Stimulation (tVNS). The brief description frames the study as a proof of concept for home use in healthy adults. Although the allocation is classified as randomized, the registry record does not report the randomization procedure, the unit or assignment being randomized, or how allocation related to age cohort. It does not describe a sham device or an untreated comparator.
The registry lists one outcome measure and no secondary outcomes. The primary measure is the System Usability Scale, reported as a mean score on a scale, with standard deviation as the planned dispersion statistic. The timeframe is Day 7 reported. Outcome summaries are listed for the Younger Cohort and Older Cohort. The registry labels the younger cohort as the control, but that label alone does not establish that it is a control condition for the older cohort or that the two cohorts differed only in age.
No statistical analysis is listed. The record does not describe allocation concealment, the handling of missing observations, or an analysis population. The reported enrollment and the outcome and safety denominators are not the same in the registry record, and the reason for this is not reported in the registry record. These design and reporting details matter when assessing whether cohort summaries can support a comparative conclusion.
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
| Stage | Younger Cohort | Older Cohort |
|---|---|---|
| STARTED | 9 | 1 |
| COMPLETED | 6 | 1 |
| NOT COMPLETED | 3 | 0 |
Reasons for not completing this period:
| Reason | Younger Cohort | Older Cohort |
|---|---|---|
| Unable to operate stimulator | 3 | 0 |
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.
| Characteristic | Unit | Younger Cohort | Older Cohort | Total |
|---|---|---|---|---|
| Participants analysed | 9 | 1 | 10 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 9 | 1 | 10 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 0 | 1 | 1 |
| Sex: Female, Male: Male | Participants | 9 | 0 | 9 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): White | Participants | 7 | 1 | 8 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
6. Primary Endpoint
The registry lists the primary outcome as System Usability Scale, measured over Day 7 reported.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | score on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the System Usability Scale score reported at Day 7. The registry describes a standard version consisting of 10 statements about the usability of the equipment. Participants report agreement with each statement on a 1 - 5 scale, where 1 is strongly disagree and 5 is strongly agree. The combined score ranges from 10-50; the record defines 50 as the highest acceptance of device usability and 10 as the lowest acceptance.
Usability is relevant to a home-use proof of concept because it concerns whether participants find the equipment acceptable to use. It is distinct from a measure of cognitive performance, which is mentioned as the project’s broader motivation. A usability score alone does not measure cognitive change, establish that stimulation caused a score, or show whether a device is practical in settings beyond the study.
The registry reports a mean of 46.25 with a standard deviation of 18.53 for the Younger Cohort, based on 6 participants. For the Older Cohort it reports a mean of 10, based on 1 participant, with no standard deviation listed. Those summaries describe the reported scores; the record does not provide participant-level observations, a confidence interval, or a comparative analysis. Because the scale has stated lower and upper bounds, interpretation should remain tied to the score definition rather than assume that a particular score represents a validated threshold for usability.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The reported younger-cohort mean is 46.25 on the stated 10-50 scale, with a standard deviation of 18.53 and an outcome sample size of 6. The mean is toward the upper end of the scale whose highest score is defined as the highest acceptance of device usability. The standard deviation indicates that the observed scores varied around that mean. It does not indicate the uncertainty of the mean by itself, and it should not be read as a confidence interval.
The older-cohort mean is 10, the lower bound of the stated score range, and is based on 1 participant. A standard deviation is not listed for that cohort. With a single reported observation, the registry does not provide information about variation among older-cohort participants. The mean therefore describes the recorded score, but does not establish what scores might be typical in the broader older population enrolled under the same criteria.
The registry does not report an inferential comparison between the cohorts. It explicitly indicates that values are missing or not estimable for a two-arm comparison of this continuous endpoint. The outcome summaries should consequently be read as descriptive, not as evidence of a statistically established difference. A numerical contrast between means would not resolve the limitations created by the older cohort’s single reported observation and the absence of a reported dispersion estimate or analysis.
The record lists the study as randomized, but does not explain what was randomized. The age-defined cohorts are not described as randomly assigned treatment groups, and the record does not identify a sham or untreated comparator for the outcome. Thus, even if the cohort means differed, these summaries would not isolate an effect of tVNS from age, cohort composition, or other differences. The project’s stated interest in cognitive performance also cannot be answered by this endpoint: the posted primary measure is equipment usability.
Precision is limited. No confidence interval is reported for either cohort, and no test result or p-value is reported. In general, a confidence interval describes the range of values compatible with the data under an analysis model; its width helps convey estimation uncertainty. Without one, and with very limited outcome information in the older cohort, the registry record does not support a precise estimate of usability in that cohort or a precise comparison between cohorts.
The results are also limited to what the registry reports at Day 7. They do not establish whether usability changed over time, whether participants continued using the equipment, or whether scores were related to cognitive performance. Those outcomes and relationships are not reported in the registry record. The most defensible interpretation is therefore a description of the available Day 7 usability summaries, with substantial limits on comparison and generalization.
9. Statistical Methods Explained
What does a mean describe?
For a continuous outcome, a mean is the arithmetic average of the recorded values in a group. It offers a compact description of the group’s scores, but it does not show the full distribution. Different sets of participant scores can have the same mean. Here, the registry reports cohort means for a bounded usability score. The mean should be interpreted with the scale definition and the amount of information behind it, rather than as a complete description of every participant’s experience.
What does the standard deviation describe?
Standard deviation describes the spread of observations around their group mean. In general, a larger standard deviation indicates greater variability in the observed scores, while a smaller one indicates that scores are closer to the mean. The younger-cohort standard deviation is 18.53. No standard deviation is reported for the older cohort. A standard deviation is not interchangeable with a standard error or a confidence interval: it describes variability among observations, while uncertainty in an estimated mean concerns how precisely the mean is known.
Why is the older-cohort spread unavailable?
The older cohort has an outcome sample size of 1 and no standard deviation listed. A spread among observations cannot be estimated from a single observed value. The reported mean of 10 therefore records the observed summary without showing the range of responses that might occur in a larger group. This is an important distinction: the absence of a standard deviation is not evidence that all older participants would have the same score.
Why is a formal comparison not available?
A comparison of two means generally requires adequate outcome information from both groups and an analysis that defines the comparison and its uncertainty. The registry says that values are missing or not estimable for a two-arm comparison of this continuous endpoint. It does not report an analysis method, estimate of a between-group effect, confidence interval, test statistic, or p-value. Accordingly, the posted cohort summaries cannot be treated as a completed inferential comparison.
Even when two group means are available, comparing them statistically depends on more than their numerical values. The analysis needs to specify the groups being compared, the estimand (the precise effect or contrast of interest), the variance assumptions, and how missing outcomes are handled. In this record, the cohort descriptions are age-based, while the randomization target and comparator are not explained. A statistical test would not by itself correct those design ambiguities.
What would a confidence interval add?
In general, a confidence interval communicates uncertainty around an estimate under specified statistical assumptions. It is not a range that contains every individual score, nor does it guarantee that a future study will produce a value inside it. A narrow interval can indicate a more precise estimate, while a wide interval signals greater uncertainty. No confidence interval is reported for the cohort means, and the available older-cohort summary does not support an estimate of its within-group variability. Precision should therefore not be inferred from the displayed means alone.
What do randomization and masking tell us?
Randomization can, when the assignment process and comparison are clearly specified, help balance measured and unmeasured characteristics across assigned groups. The record classifies allocation as randomized, but does not report the assignment procedure or what was randomized. It identifies no masking. Without further detail, the label “randomized” is not enough to establish that the reported age cohorts constitute randomized treatment groups or that the outcome estimates a treatment effect. The record also does not describe a sham or untreated comparator.
Masking refers to keeping participants, study staff, or outcome assessors unaware of assigned treatment when applicable. The registry records no masking. For a self-reported usability measure, participants’ awareness of the equipment and study context may be relevant to how responses are interpreted. The record does not explain whether any procedures were used to limit influence on responses, so such procedures should not be assumed.
How should planning calculations be understood?
The registry describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such a calculation is a planning exercise: it asks what sample size might be needed under specified assumptions to detect a chosen fraction of an effect. It is not an observed result, does not show that the study had a particular probability of detecting an effect, and is not observed power. The record’s stated planning approach does not replace the missing comparative endpoint analysis. Since the registry does not give an estimable two-arm comparison for this outcome, the planning assumptions should not be read as validating a treatment-effect estimate.
More generally, normal approximations are most useful when their assumptions fit the design and outcome information. A bounded scale, limited observations, or substantial variability can affect how well an approximation represents uncertainty. Over-dispersion, in general, means variability is greater than a model assumes; if present, it can make model-based uncertainty too small. The registry does not report a model diagnostic or variance analysis, so there is no basis to say whether over-dispersion occurred in this study.
The record reports no statistical analysis plan or analysis method. It does not state whether the primary endpoint was analyzed as a continuous score under a particular model, whether any adjustment was planned, or how deviations from the intended measurement schedule would be handled. These details are needed to reproduce an inferential analysis and assess whether its assumptions are appropriate. In their absence, the reported outcome values are best read as descriptive registry summaries.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure and no secondary outcomes. It reports no analyses and does not report a multiplicity procedure. Multiplicity concerns the increased chance of a false-positive finding when many hypotheses or outcomes are tested. With no analyses posted, there is no reported set of tests whose multiplicity adjustment can be evaluated. The record does not state whether other analyses were planned or conducted outside the registry.
Missing-data handling is not reported in the registry record. The record provides a mean and standard deviation for the younger cohort and a mean without a standard deviation for the older cohort. It does not explain whether all eligible participants contributed an outcome, whether any Day 7 measurements were unavailable, or how unavailable measurements would have been handled. The difference between the enrollment figure, outcome sample sizes, and safety denominators is not explained in the registry record; those quantities should not be silently treated as interchangeable.
The analysis population is also not reported in the registry record. There is no statement of whether the outcome summaries include all enrolled participants, participants who used the device, or another defined set. The registry does not report an intention-to-treat or per-protocol analysis. Without a stated population and missing-data approach, the scope of the reported summaries cannot be fully determined.
These omissions do not establish that data were missing or that analyses were selectively reported. They mean that the registry record does not provide enough information to assess those possibilities. The available outcome summaries should therefore be interpreted as the posted descriptive results, without assumptions about unreported analysis decisions.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Younger Cohort | 0 | 9 | 0.0% |
| Older Cohort | 0 | 1 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Younger Cohort | 0 of 9 |
| Older Cohort | 0 of 1 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Younger Cohort | 0 of 9 |
| Older Cohort | 0 of 1 |
The registry lists serious adverse event figures by cohort. For the Younger Cohort, 9 participants are listed as at risk and 0 as affected by a serious adverse event. For the Older Cohort, 1 participant is listed as at risk and 0 as affected. Deaths are listed as 0 in each cohort. The record lists 9 at risk for other adverse events in the younger cohort and 1 in the older cohort, with 0 affected in each.
These are counts recorded in the registry, not estimates of comparative safety. The denominators listed for safety differ from the outcome sample sizes, and the reason is not reported in the registry record. The figures do not establish that no event could occur outside the observation and reporting captured by the record. The registry does not provide additional detail about event definitions, observation duration for safety, or a narrative of events. The top serious-event terms list is empty, so no serious-event terms are posted there.
In general, an adverse-event count is interpreted in relation to how events were defined, how long participants were observed, and which participants were included. Without those details, the reported zeros should be described narrowly as zero affected in the listed registry groups, rather than as proof of absence of risk or as a comparison between cohorts.
12. What the Result Does, and Does Not, Mean
The posted results describe usability scores at Day 7 in two age-defined cohorts. The younger-cohort mean is 46.25, with standard deviation 18.53, based on 6 participants. The older-cohort mean is 10, based on 1 participant; no standard deviation is reported for that cohort. The scale is defined as ranging from 10-50, with higher scores indicating greater acceptance of device usability.
These values do not establish a treatment effect. The registry labels allocation randomized but does not report what was randomized, and it does not describe a separate sham or untreated comparator. The cohort summaries are not accompanied by an inferential comparison. The record specifically indicates that a two-arm comparison of this continuous endpoint was not estimable. It is therefore not possible to use the posted outcome summaries to determine whether the cohorts differ beyond the observed descriptive values or whether any difference is attributable to tVNS.
The outcome also does not answer the project’s broader question about cognitive performance. The record’s primary endpoint is usability, not a cognitive test. No secondary outcomes are listed, and no cognitive-performance result is posted. The usability data cannot show whether tVNS changed cognitive performance, nor whether usability scores are associated with such a change.
The result should not be generalized beyond the limited information in the registry. The older-cohort outcome is based on a single observation, and no interval estimate or variability measure is available for that cohort. The record does not provide enough detail about participant selection, missing measurements, or the analysis population to assess how representative the summaries are. The result is best understood as a small set of reported Day 7 usability summaries, not as a definitive estimate of usability in healthy younger or older adults or a conclusion about device effectiveness.
13. Why This Trial Matters Statistically
This record illustrates why the endpoint and the broader study rationale must be kept distinct. The project describes tVNS in relation to cognitive performance, while its posted primary outcome measures usability. Usability is a relevant aspect of home-use feasibility, but it does not substitute for a measure of cognition. A conclusion should match the outcome actually reported.
It also shows why group means require context. A mean can appear straightforward, but the amount of information behind it and the estimate of variability affect how much can be inferred. The younger cohort has a mean and standard deviation; the older cohort has one reported observation and no standard deviation. Treating those summaries as equally informative would obscure the difference in precision.
The registry’s randomized label does not, by itself, define a causal comparison. Randomization is useful when the assignment and comparison are clear. Here, the age-based cohorts, control label, and randomization classification are not connected by an explanation of what was assigned. This makes it important to separate the descriptive outcome from claims about an intervention effect.
Finally, the absence of a reported analysis is an interpretive limit rather than a result in itself. The record lists no analyses and says a two-arm comparison is not estimable. A careful reading therefore avoids inferring statistical significance, effect size, or precision from the means alone. These distinctions are useful across clinical research: a descriptive result, a causal estimate, and a planning calculation answer different questions and should not be treated as interchangeable.
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 registry record leaves important design details unspecified. Although allocation is classified as randomized, it does not describe the randomization process, what was assigned, or how the assignment relates to the younger and older cohorts. The younger cohort is labeled as control, but a separate sham or untreated group is not described. This makes the intended comparison unclear.
The primary outcome information is limited. The older cohort has an outcome sample size of 1 and no reported standard deviation. The registry reports no confidence intervals, test results, or estimated between-cohort effect, and states that a two-arm comparison is not estimable. The younger cohort’s mean and standard deviation provide descriptive information but do not resolve the missing comparative evidence.
The registry lists enrollment as 10, while the outcome and safety summaries list different denominators. The explanation for these differences is not reported in the registry record. The analysis population, missing-data procedures, and whether every participant completed the Day 7 measure are not reported. These omissions prevent a full assessment of how the posted summaries relate to enrolled participants.
The outcome is usability, not cognitive performance, and only one outcome measure is listed. The record does not report a cognitive outcome, a measure of longer-term usability, or enough intervention detail to assess the home-use protocol. No masking is listed. The setting and cohorts are limited to healthy adults in the specified age ranges, so the posted results do not establish what would be observed in other populations or circumstances.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Home Operations Utilizing Stimulation — NCT04484285.
- Registry record last updated 2025-04-20; status last verified 2025-04.
- Results first posted 2025-04-11.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
Home Operations Utilizing Stimulation is listed as a completed randomized parallel study with no masking, sponsored by the University of Florida. Its stated aim is proof of concept for home use of tVNS in healthy younger and older adults. The registry lists enrollment of 10 and one primary outcome: the System Usability Scale at Day 7.
The Younger Cohort has a reported mean score of 46.25 and standard deviation of 18.53, based on 6 participants. The Older Cohort has a reported mean of 10, based on 1 participant, with no standard deviation listed. The registry reports no analyses and says a two-arm comparison of the continuous endpoint is not estimable. It does not explain the randomization target, analysis population, or differences among the listed outcome and safety denominators. The outcome is descriptive usability information and does not establish a cognitive-performance result or a treatment effect.