Transcranial Direct Current Stimulation Therapy for Bipolar Depression: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Transcranial Direct Current Stimulation Therapy for Bipolar Depression (NCT05436613), a na na study. The primary outcome is Number of Participants With Clinical Response [ Time Frame: At 6 Weeks Following Course of tDCS Treatment ].

2. Clinical Question

The registry record concerns whether transcranial direct current stimulation (tDCS) can be provided as a home-based treatment for adults with bipolar disorder experiencing bipolar depression. Its primary clinical question is narrower and measurable: how many enrolled participants met the registry’s definition of clinical response at 6 weeks following the course of tDCS treatment?

The study’s brief description raises a practical question about home-based delivery. The listed secondary outcomes—participant retention at the end of treatment and participant acceptability questionnaire scales—also concern participation and acceptability. The registry record does not report results for those outcomes, so the degree of retention, acceptability, or clinical response cannot be established from the posted results.

3. Trial Design

This is a completed, single-group study of a device intervention. The registry lists University of East London as sponsor, records the phase as NA, and gives an enrollment of 44. The study began on 2022-05-01, had primary completion on 2024-05-30, and is marked COMPLETED. Allocation is recorded as NA, and masking is NONE.

All participants were assigned to the intervention described in the registry: active transcranial direct current stimulation. The course lasts 6 weeks, with 5 sessions per week for the first 3 weeks and 2 sessions per week for the following 3 weeks. Each session lasts 30 minutes, making 21 sessions in total. The record does not give device settings or further implementation details.

A single-group design records outcomes among people who receive the intervention but does not compare them with a concurrent group receiving a different treatment or no intervention. Consequently, changes from baseline may be described, but the design alone cannot distinguish intervention effects from other explanations for change over time. The registry’s allocation entry of NA is consistent with the absence of a listed randomized comparison; the study model is SINGLE GROUP.

The research question in the brief description is whether tDCS can be provided as a home-based treatment. The official title describes the study as community-based. The record describes the active treatment schedule but does not report additional details about how treatment was delivered, participant support, or adherence. It lists retention and acceptability as secondary outcomes, but does not post their results. No separate control arm, masking procedure, or comparative treatment effect is reported in the registry record.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Intention to Treat analysis including all participants who enrolled

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 Number of Participants With Clinical Response [ Time Frame: At 6 Weeks Following Course of tDCS Treatment ], measured over 6 weeks.

The primary endpoint is the number of participants with clinical response, assessed at 6 weeks following the course of tDCS treatment. Response is defined as improvement of 50% or more from baseline on the clinician-rated Montgomery Asberg Depression Rating Scale (MADRS). The primary population is described as all participants who enrolled, under an intention-to-treat approach.

A response threshold turns a continuous symptom score into a participant count: each person is classified according to whether their change meets the stated criterion. Such an endpoint can be clinically interpretable as the proportion or number meeting a prespecified level of improvement, but it discards information about the size and pattern of score changes outside that threshold. The registry specifies the count as the primary measure; it does not give the individual score distribution or a separate continuous-score result.

The registry record does not report the observed number of participants who met the response definition. It also does not report a confidence interval or other estimate of uncertainty for this primary endpoint. Therefore, the endpoint definition is available, but the magnitude and precision of the clinical-response result cannot be assessed from the posted results. The registry record also does not report further details about MADRS assessment procedures, assessor training, or the handling of assessments that were not completed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group design estimate?

This study is described as SINGLE GROUP, with allocation recorded as NA and masking as NONE. In general, a single-group study can describe participant outcomes after an intervention and may compare follow-up measurements with baseline measurements. It does not contain a concurrent comparison group. A before-and-after change therefore does not separate the effect of treatment from changes that might have occurred over time for other reasons. Random allocation in a comparative study can help balance prognostic factors between groups; no randomized comparison is listed in this record.

The absence of masking matters to interpretation in general, particularly for outcomes involving judgment or participant reports. Knowledge of treatment can influence expectations, assessment, or reporting. The registry does not describe procedures intended to reduce such influences, and it does not report further assessor details. That does not demonstrate that bias occurred; it means the record does not allow readers to evaluate those safeguards.

How should a response count be understood?

The primary endpoint counts participants meeting a binary definition: a clinician-rated MADRS score improvement of 50% or more from baseline. A binary endpoint is easy to state as the number who meet a criterion, but it treats people on either side of the cutoff differently even when their score changes are similar. It also does not show the range of changes among participants who do not meet the threshold. In general, reporting a count alongside an uncertainty interval helps distinguish the point estimate from its precision. The registry record does not report the response count or an interval.

The endpoint time frame is 6 weeks following the course of treatment. The intervention itself is described as a 6-week course. The record does not provide additional timing details that clarify the exact assessment schedule or whether any assessments outside that endpoint were used for the primary analysis. It also does not report a protocol for repeated or missed assessments.

What does intention-to-treat mean in this record?

The primary population is described as an intention-to-treat analysis including all participants who enrolled. In general, intention-to-treat analysis aims to retain participants in the group to which they were assigned, regardless of treatment adherence. In a single-group study, the central population statement is that all enrolled participants are intended to be included. It does not establish that every participant has an observed endpoint value. The record does not report how missing endpoint data were addressed, whether any participants discontinued, or how the analysis dealt with incomplete measurements. Thus, the stated population and the number with outcome data should not be assumed to be identical.

What statistical analysis is documented?

The registry record does not report a statistical analysis plan or analysis results for the primary endpoint. It does not report a confidence interval, hypothesis test, model, adjustment procedure, or a method for handling covariates. The outcome entry identifies a participant count and a response definition, but those details alone do not specify how uncertainty or missingness would be handled. The record also does not report whether any interim analyses were planned or conducted, or how the enrollment target was chosen.

In general, a confidence interval communicates the range of estimates reasonably compatible with the observed data under the method’s assumptions. A narrower interval indicates greater precision, while a wider interval indicates more uncertainty. A p-value, when reported, evaluates the compatibility of data with a specified null model; it does not measure clinical importance or the probability that a treatment works. Neither measure is posted for the primary result in this registry record.

Why does comparison matter?

A treatment effect in a comparative trial is commonly expressed as a contrast between outcomes in intervention and comparator groups. This study has no listed comparator, so there is no between-group contrast to estimate. In general, comparative designs provide a reference for interpreting outcomes over the same period, while single-group designs can describe the observed course among enrolled participants. The designs answer different questions and support different strengths of inference.

The sample-size assumptions described for planning illustrations are not the study’s own design rationale. They are not evidence of an observed treatment effect or of achieved power. No sample-size justification is reported in the registry record. The number enrolled, by itself, cannot establish whether the study was adequately powered for its primary outcome; that assessment would require a documented target effect, assumptions, and analysis plan, none of which are reported in the registry record.

How should adverse-event counts be read statistically?

Event counts are descriptive unless their definitions, observation periods, and analysis methods are also known. In general, a count of participants with an event differs from a count of all event episodes, because one person may experience more than one event. The registry lists participants at risk and affected, but does not provide event-level detail, exposure-adjusted rates, or a comparator. The reported figures should therefore be read as the registry’s participant counts, not as a comparative risk estimate.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Device: Transcranial Direct Current Stimulation")
n      <- c(44)
events <- c(34)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Device: Transcranial Direct Current Stimulation  44  34  77.3  62.2  88.5  63.0  87.2  62.9  87.1

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome and two secondary outcomes: participant retention at the end of treatment and participant acceptability questionnaire scales. It also states that there are 4 outcome measures, but does not provide results for the clinical-response endpoint or the secondary outcomes. Statistical analysis results are not reported in the registry record.

Multiplicity arises in general when several outcomes, time points, or statistical comparisons are examined. If many tests are conducted, the chance of at least one apparently notable result can increase unless the analysis plan accounts for that. A prespecified primary endpoint can help distinguish the principal question from supporting outcomes. The registry identifies a primary endpoint, but it does not report a multiplicity strategy or specify how the additional outcome measures were handled analytically. No adjustment should be assumed.

The primary population is described as including all participants who enrolled. That statement identifies the intended analysis population, but does not explain how missing outcome data were handled. The record does not report the number with an observed MADRS assessment, reasons for any missing measurements, imputation methods, sensitivity analyses, or whether participants who stopped treatment remained represented in the endpoint analysis.

In general, missing data can affect an estimate when the chance of having a measurement is related to a participant’s outcome or other characteristics. Excluding participants with missing follow-up may produce a different result from an approach that retains them, depending on why their data are missing. Without the extent and handling of missingness, readers cannot assess its potential influence on the primary result.

The registry record also does not report a detailed statistical plan, interim-analysis procedures, or a sample-size justification. The absence of those details is a limitation of the record, not evidence that such procedures did or did not occur outside it.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: throat infection (2.3%).

The registry lists adverse events for the transcranial direct current stimulation group, with 44 participants at risk. It records 1 participant with a serious adverse event, 43 participants with other adverse events, and 0 deaths. Throat infection appears among the listed serious-event terms at 2.3%.

These entries are counts of participants affected, not necessarily counts of every event episode. The registry record does not report the event narratives, timing, duration, severity details beyond the serious-event classification, or whether events were considered related to the device. The throat-infection listing should therefore be read as a reported serious-event term, not as proof that the device caused it.

In general, adverse-event counts need context about definitions, observation time, exposure, and ascertainment. A single-group study also has no concurrent comparator for assessing whether the observed counts differ from those under another treatment or no intervention. The figures describe the registry’s safety reporting for this group; they do not establish comparative risk or explain the clinical course of individual events.

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

The registry record establishes that a completed, single-group study enrolled 44 participants to receive a course of active tDCS for bipolar depression. It specifies a primary clinical-response definition based on clinician-rated MADRS improvement of 50% or more from baseline, assessed at 6 weeks following the course. It also lists retention and acceptability as secondary outcomes and reports adverse-event participant counts.

The primary response count and secondary outcome results are not reported in the registry record. Consequently, the posted information does not show how many participants met the clinical-response criterion, how many completed treatment, or how participants rated acceptability. There is also no posted statistical estimate of uncertainty for the primary endpoint. The intervention schedule and enrollment count cannot substitute for those outcomes.

The study’s single-group structure is important. Even if a before-and-after outcome were available, change within participants would not, by itself, establish that tDCS caused the change. Without a comparison group, it is not possible to estimate how outcomes would have differed under another approach over the same period. The record also does not give information about concurrent care or other factors that could shape outcomes.

The adverse-event counts document reported events in the intervention group, including one participant with a serious adverse event and no deaths. They do not quantify a comparative safety difference or establish causal attribution. The registry’s serious-event term listing includes throat infection at 2.3%, but further detail is not reported.

In general, study findings are most informative when design, outcome estimates, uncertainty, missing-data handling, and analysis methods can be considered together. In this case, the registry supports a description of the planned question, intervention, endpoint, and some safety counts, but not a conclusion about the magnitude of clinical response, causal efficacy, or comparative safety.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of how the design determines the question that can be answered. A single-group study can document a treatment schedule and describe outcomes among participants, but it does not provide the concurrent contrast needed to estimate how outcomes differ from a comparator. That distinction is essential when interpreting any change from baseline.

The primary endpoint uses a clinically framed threshold: a 50% or more improvement on clinician-rated MADRS from baseline. Threshold endpoints can be readily communicated as participant counts, while losing detail about the size of changes and variation in scores. The registry defines the endpoint and its timing, but does not post its observed count. This illustrates why a clear outcome definition is only one part of a complete statistical report; the estimate and its uncertainty are also needed for interpretation.

The study also connects statistical evaluation with practical delivery. Its brief description asks whether tDCS can be provided as a home-based treatment, and the listed secondary outcomes include retention and acceptability. Those outcomes could describe practical aspects of participation, but their results are not reported in the registry record. Without them, the practical question remains unresolved in the posted information.

Finally, the record shows why enrollment and safety counts should not be confused with evidence of treatment effect. Enrollment describes the study population size, while adverse-event counts describe reported events in the intervention group. Neither supplies the missing clinical-response estimate or a comparative treatment effect. Read together, the design and reporting limits clarify what can be described and what remains unknown from the registry record.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The principal trial-specific limitation is the single-group design. With no comparator, the study cannot directly estimate a difference in clinical response between tDCS and another treatment or no intervention. Any observed change from baseline would be open to alternative explanations, and the registry record does not report a comparative analysis.

The primary outcome result is not reported. Although the response definition, assessment timing, and intended analysis population are identified, the registry does not state the number meeting the threshold, the number assessed, or an uncertainty estimate. This prevents evaluation of both the magnitude and precision of the primary result. The listed retention and acceptability outcomes also lack posted results.

The record does not report how missing measurements were handled, whether treatment discontinuations occurred, or whether all enrolled participants contributed outcome data. It also does not provide details of concurrent treatment, adherence, device settings, assessor procedures, or the implementation of home-based treatment. These omissions limit assessment of how the intervention was delivered and how the outcome was measured.

No statistical analysis plan, multiplicity procedure, interim-analysis information, or sample-size justification is reported in the registry record. The record also does not report detailed event narratives or causal attribution for adverse events. These limitations concern what can be evaluated from the record; they do not establish that additional procedures or information were absent from the conduct of the study.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Transcranial Direct Current Stimulation Therapy for Bipolar Depression — NCT05436613.
• Registry record last updated 2025-08-14; status last verified 2025-07.
• Results first posted 2025-08-14.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry record describes NCT05436613, “Transcranial Direct Current Stimulation Therapy for Bipolar Depression,” with the official title “Community-based Transcranial Direct Current Stimulation Treatment for Bipolar Depression.” University of East London is listed as sponsor. The study is marked COMPLETED, with enrollment of 44, a start date of 2022-05-01, and primary completion on 2024-05-30.

The design is SINGLE GROUP, allocation is NA, and masking is NONE. The intervention is a 6-week course of active tDCS comprising 21 sessions. The primary endpoint is the number of participants meeting the clinician-rated MADRS response definition at 6 weeks following treatment. The primary result and secondary outcome results are not reported in the registry record.

The adverse-event listing records 1 participant with a serious adverse event, 43 with other adverse events, and 0 deaths. Throat infection is listed among serious-event terms at 2.3%. The registry record does not report a comparator or statistical analysis results.