Treating Civilian Traumatic Brain Injury With High Definition Transcranial Direct Current Stimulation (ciTBI-HDtDCS): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Treating Civilian Traumatic Brain Injury With High Definition Transcranial Direct Current Stimulation (ciTBI-HDtDCS) (NCT05408975), a randomized na study. The primary outcome is The Controlled Oral Word Association Test.

2. Clinical Question

3. Trial Design

The registry describes a randomized, triple-masked, crossover study. Participants were assigned to one of two treatment sequences: active stimulation followed by sham stimulation, or sham stimulation followed by active stimulation. This ordering is central to interpreting a crossover study: the treatment contrast is intended to be assessed within a sequence in which participants experience both conditions. The registry record does not identify which people were masked, how masking was maintained, or how treatment periods were separated.

The enrollment is listed as 5, and the study status is completed. The registry lists a start date of 2023-01-01 and a primary completion date of 2024-11-30. These dates describe the study record, not the timing of an individual participant's assessments. The phase is listed as NA.

The primary outcome is the Controlled Oral Word Association Test, with a stated timeframe of treatment differences in change from baseline to immediately and 2-months post-treatment. The registry also lists neuropsychological assessments of other cognitive abilities and EEG measures as secondary assessments. Named secondary outcomes include the Trail Making Test - Part A, the Trail Making Test - Part B, Digit Span Forward, Digit Span Backward, Rey-Osterrieth Complex Figure Test - Delayed Recall, and the Digit Symbol Substitution Test. The record lists 16 outcome measures overall.

The primary-outcome population description states that n=3 assigned to the Active to Sham arm completed phase 1, with baseline, immediately post-phase-1-intervention, and 8 weeks after post-phase-1-intervention assessments. It also states that n=2 assigned to the Active to Sham arm completed phase 2, with immediately post-phase-2-intervention and 8 weeks after post-phase-2-intervention assessments. The description is incomplete in the registry record, so it does not establish the full analysis population or provide a complete account of assessment completion across sequences.

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.

Baseline

Immediately Post Phase 1 Intervention

8 Weeks Post Phase 1 Intervention

Immediately Post Phase 2 Intervention

Analysis population for the primary outcome, as defined in the registry: n=3 assigned to Active to Sham arm completed phase 1 (Baseline, Immediately post phase 1 intervention, 8 weeks after post phase 1 intervention), and only n=2 assigned to Active to Sham arm completed phase 2 (Immediately post phase 2 intervention, 8 weeks after post phase 2 intervention). n=2 assigned to Sham to Active completed both phases 1 \&2.

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 The Controlled Oral Word Association Test, measured over Treatment differences (active versus sham) in change from Baseline to immediately and 2-months Post-Treatment..

The primary endpoint is performance on the Controlled Oral Word Association Test, a neuropsychological assessment of verbal retrieval. The registry describes the metric as the total number of correct items generated for three different letters, with a stated range from 0 (minimum) to 200 (maximum). Larger values indicate better performance. This makes the outcome a continuous measure: its values represent a score across a range rather than membership in a category.

The study asks whether the change in this score differs between active and sham stimulation. The stated timeframe includes change from baseline to immediately after treatment and at the 2-months post-treatment assessment. Considering change over time is relevant because the question concerns treatment-associated differences in performance, rather than only the score at a single assessment. The crossover design also means treatment order and assessment period matter to the interpretation; the record does not report a period-specific analysis.

The test is used because it assesses the verbal retrieval difficulty targeted by the study. A change in the score is an assessment result, not by itself an explanation of why performance changed. Interpreting the comparison requires the size and uncertainty of the active-versus-sham contrast, along with information about the analysis population and handling of repeated assessments. Those statistical results and details are not reported in the registry record. The endpoint description therefore identifies what was measured and how its direction is interpreted, but does not establish the size or precision of any treatment difference.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record describes a randomized, triple-masked crossover study with active and sham stimulation. General statistical explanation can clarify what such a design is intended to estimate, but the registry record does not report the detailed statistical model or procedures used to analyze this study.

What does a crossover comparison mean?

In a crossover design, participants receive both study conditions in an assigned order. The ciTBI-HDtDCS sequences are active followed by sham, and sham followed by active. In general, comparing conditions within participants can account for stable differences between people, because each participant contributes observations under both conditions. The interpretation still depends on how period, sequence, and repeated measurements are handled. The registry record does not report whether the analysis included these factors, how a possible carryover effect was considered, or whether there was a washout interval.

Random assignment concerns how participants enter the treatment sequences. It does not alone guarantee that all planned assessments are completed or that an analysis is free of bias. Masking can help reduce the influence of expectations in some parts of a study, but the record does not specify which groups of people were masked or how masking success was assessed. These details are not reported in the registry record.

What does the endpoint measure?

The primary outcome is a continuous score on the Controlled Oral Word Association Test. The record specifies a mean as the outcome parameter and standard deviation as the dispersion measure. In general, a mean describes the average score in a group or condition, while a standard deviation describes the spread of individual scores around that mean. A treatment comparison would need to state how the mean scores or changes were contrasted, and account for the design and timing of observations. The record does not provide those estimates or the model used to obtain them.

The endpoint description gives the score's range and direction: higher numbers indicate better performance. That direction helps readers understand the scale, but it does not determine whether any observed difference is important or precise. A score difference could be estimated with substantial uncertainty, especially when outcome information is limited. A confidence interval, in general, communicates a range of values compatible with the data and the specified statistical method. No confidence interval for the primary treatment contrast is reported in the registry record.

Why do repeated time points matter?

The stated primary timeframe includes assessments immediately after treatment and at 2-months post-treatment, in relation to baseline. These are repeated measurements, not separate unrelated outcomes. General methods for repeated data account for the fact that scores from the same participant may be correlated. Ignoring that correlation can misstate uncertainty. The record does not specify whether changes were analyzed separately by time point, jointly, or through another approach. It also does not report a single numerical comparison that combines or distinguishes the time points.

Over-dispersion is a general concern when the observed variability is greater than a model assumes, which can make uncertainty estimates too small if the model is not appropriate. The primary score is described as a continuous mean outcome with standard deviation, but no model diagnostics or over-dispersion assessment are reported. This concept therefore explains a possible methodological issue in general; it is not a claim that over-dispersion occurred in this study.

How should planning figures be read?

The registry's sample-size assumptions describe a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. Such figures are planning illustrations, not observed participant results and not evidence of a study's achieved power. The assumptions state that the effect to detect is a stated fraction of the observed effect. The record does not provide a primary comparison reduced to one effect, and the primary outcome is identified as having several categories or time points rather than a single comparison. No numerical planning estimate is therefore interpreted.

In general, a planning calculation asks how many participants per arm might be needed under specified assumptions to detect a chosen effect with a chosen level of power. Its answer depends on the assumed effect, variability, allocation, and statistical method. It is not a substitute for reporting the effect and uncertainty observed in a completed trial. The record does not report the trial's own sample-size justification or the detailed basis for its enrollment target.

What can be inferred from the posted analysis record?

The registry lists 0 analyses. It does not report a test statistic, p-value, confidence interval, adjusted estimate, or model specification for the primary endpoint. A p-value, in general, describes how incompatible the observed data are with a specified null model under assumptions; it is not a measure of effect size or clinical importance. Since no primary-outcome test result is reported, there is no p-value to interpret.

These omissions do not establish that no analysis was conducted outside the registry. They mean that the statistical analysis and results cannot be assessed from the registry record. The appropriate reading is therefore descriptive: the record documents the design, endpoint, and some assessment completion information, but does not report a numerical primary treatment-effect analysis.

10. Multiplicity, Missing Data and Analysis Populations

The record lists 16 outcome measures, including the primary Controlled Oral Word Association Test and named secondary neuropsychological measures. The primary outcome timeframe includes immediate and 2-months post-treatment assessments, and the record indicates that the primary outcome has several categories or time points and is not reduced to one comparison. This creates multiple possible outcome contrasts to interpret. In general, when many outcomes or time points are tested, the chance of finding an apparently notable result by chance can increase unless the analysis plan addresses multiplicity. The registry record does not report a multiplicity adjustment, hierarchy among outcomes, or a prespecified strategy for interpreting multiple time points.

The record lists 0 analyses, so it does not provide the primary or secondary analysis results needed to assess which comparisons were conducted. The statistical analysis plan, including any prespecified primary contrast, is not reported in the registry record. The brief description identifies additional cognitive and EEG measures and an interest in predicting responses from baseline assessments, but no analysis results for those aims are reported.

Missing-data handling is also not reported. The primary-outcome population description states that n=3 in the Active to Sham arm completed phase 1 and n=2 completed phase 2, with assessments at different listed time points. These counts suggest that completion varied across phases, but they do not establish the reasons, the status of every measurement, or the number of observations used in any analysis. The record does not state whether missing measurements were excluded, imputed, or addressed with a repeated-measures method.

The analysis population is not fully described. The registry record does not report whether results were analyzed according to randomized sequence, treatment received, or another population definition. Without a stated population, missing-data method, multiplicity approach, and reported estimates, readers cannot assess how robust a treatment comparison would be to alternative analytical choices.

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.

The serious adverse event figures are reported by randomized sequence. For the Active to Sham Transcranial Direct Current Stimulation group, the number at risk for serious adverse events is 3, and the number affected is 0; deaths are 0. For the Sham to Active Transcranial Direct Current Stimulation group, the number at risk is 2, the number affected is 0, and deaths are 0. These are the registry's reported serious-event figures for the named groups.

The record also reports other, non-serious adverse event figures: the number at risk is 3 and the number affected is 0 in the Active to Sham group; the number at risk is 2 and the number affected is 0 in the Sham to Active group. The serious-event term list is empty. These entries describe what the registry reports; they should not be read as proof that no events of any kind occurred outside the reported categories or reporting period.

In general, adverse event counts are interpreted in light of the number of people assessed, the length of follow-up, event definitions, and completeness of reporting. The record does not give additional detail about event collection or exposure time. With the small enrollment listed in the record and the reported risk counts, the figures offer limited information about uncommon harms. They do not establish comparative safety or justify a medical recommendation.

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

The registry record establishes that ciTBI-HDtDCS was a completed randomized, triple-masked crossover study of active and sham tDCS in civilians with histories of traumatic brain injury and verbal retrieval difficulties. It specifies the Controlled Oral Word Association Test as the primary outcome and describes the intended assessment times. The record also lists secondary cognitive measures and EEG assessments.

It does not, however, provide a numerical primary treatment comparison. There is no reported mean change by condition, active-versus-sham estimate, confidence interval, or significance test. As a result, the posted information cannot establish the direction, magnitude, or precision of any difference in verbal retrieval scores. The absence of a reported statistical result is not evidence that the treatments had the same effect, and it is not evidence that either treatment had a particular effect.

The crossover format and randomized order are relevant design features, but do not by themselves answer the study question. Interpretation requires the outcome data and the analysis used to account for repeated assessments, treatment order, and incomplete follow-up. Those details are not reported in the registry record. The listed completion information indicates that phase completion differed within the Active to Sham sequence, but does not show how the available observations were incorporated into an analysis.

The safety record reports zero participants affected by serious adverse events and zero deaths in each listed sequence group, as well as zero affected by other adverse events. These are limited descriptive counts, not a comprehensive guarantee about safety. The registry record does not report detailed safety methods or further event context.

Thus, the record supports a description of the research question, design, endpoint, and reported adverse-event counts. It does not support a conclusion about whether active stimulation changes verbal retrieval, how large such a change might be, whether it persists, or how its benefits and risks compare. Those conclusions require reported outcome analyses and their uncertainty.

13. Why This Trial Matters Statistically

This trial is statistically notable as a small randomized crossover study focused on a specific cognitive outcome after civilian traumatic brain injury. A crossover design can make within-participant comparisons relevant, because each participant is assigned to experience active and sham stimulation in a different order. At the same time, such a design requires careful attention to treatment period, sequence, repeated measurement, and possible carryover. The registry record establishes the sequences but does not describe the analysis of these features.

The primary endpoint is a continuous verbal-retrieval score measured over time. That structure raises practical statistical questions: how to define the treatment contrast, how to handle multiple time points, and how to account for incomplete assessments. The record documents several assessment occasions and differing phase completion in the Active to Sham group, but does not report the analysis population or missing-data method. These are not minor reporting details; they determine what estimate is being interpreted and how much uncertainty surrounds it.

The record also illustrates the distinction between a completed study and a reported result. Completion status and an endpoint definition do not reveal an estimated treatment effect. In this case, the registry lists 0 analyses and does not reduce the primary outcome to a single comparison. Without a reported estimate and uncertainty interval, the study question remains statistically unanswered in the registry record.

Finally, the sample-size assumptions are described as a planning illustration based on an observed effect, rather than the trial's own design justification. Planning calculations can inform future research when their assumptions and target effect are clear, but they cannot replace transparent reporting of this study's observed data. The record does not provide enough reported primary-outcome analysis to evaluate a treatment difference or its precision.

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 central limitation for interpretation is the absence of reported primary-outcome analysis results. The registry specifies the outcome, score direction, and assessment timeframe, but gives no treatment-effect estimate, confidence interval, or hypothesis-test result. It therefore does not quantify the active-versus-sham contrast or its precision.

The primary outcome is described across several time points and is not reduced to one comparison. The registry record does not explain how these repeated assessments were modeled or how multiplicity was handled. It also does not report whether the analysis accounted for treatment sequence, period, or carryover in the crossover design. The masking description is limited to the term triple; which people were masked and how masking was maintained are not reported.

The outcome population description includes phase-specific completion information for the Active to Sham arm, but is incomplete. The record does not provide a complete participant flow for both sequences, a full description of the analysis population, reasons for missing assessments, or the method used to handle missing data. These omissions limit assessment of how representative the analyzed observations would be of all randomized participants.

Enrollment is listed as 5, so the study is small in scale. In general, limited participant numbers can make estimates imprecise and reduce the ability to characterize uncommon adverse events. The registry record does not report the trial's sample-size justification. Its planning assumptions describe an illustration, not a documented design rationale.

Finally, the registry reports 0 analyses and does not present results for the listed secondary outcomes or the stated EEG and predictor aims. Consequently, those outcomes cannot be used to add context to the primary question. These limitations describe gaps in the registry record and do not establish what analyses may have been conducted elsewhere.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Treating Civilian Traumatic Brain Injury With High Definition Transcranial Direct Current Stimulation (ciTBI-HDtDCS) — NCT05408975.
• Registry record last updated 2026-02-02; status last verified 2026-01.
• Results first posted 2026-02-02.
• 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 registry record describes NCT05408975, titled Treating Civilian Traumatic Brain Injury With High Definition Transcranial Direct Current Stimulation (ciTBI-HDtDCS). It is a completed randomized, triple-masked crossover study with enrollment listed as 5. Participants were assigned to active-to-sham or sham-to-active tDCS sequences.

The primary outcome is the Controlled Oral Word Association Test, a continuous verbal-retrieval score for which higher numbers indicate better performance. The stated timeframe compares change from baseline at immediate and 2-months post-treatment assessments. The registry lists 16 outcome measures and 0 analyses. It does not report a reduced primary treatment comparison or its uncertainty.

The serious adverse event record reports 0 affected participants and 0 deaths in each sequence group. The reported other adverse event counts are also 0 affected in each group. These figures are descriptive and do not establish comparative safety. The statistical interpretation is constrained by absent outcome analyses and unreported details about missing data, multiplicity, and the analysis population.