Management of Chronic Pain and PTSD in Gulf War Veterans With tDCS+Prolonged Exposure: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Management of Chronic Pain and PTSD in Gulf War Veterans With tDCS+Prolonged Exposure (NCT04236284), a na na study. The primary outcome is Feasibility of Recruitment as Assessed by Number of Participants Enrolled in the Study.

2. Clinical Question

The registry describes the broader purpose as integrating and refining tDCS with PE and gathering feasibility information, including pilot testing, recruitment, attrition, and assessment. Its stated proposal describes an aim involving 15 Gulf War veterans, while the registry enrollment field lists 21. These figures describe the proposal’s stated aim and the recorded enrollment, respectively; the registry record does not explain the difference.

The clinical motivation in the record is that chronic pain and PTSD may occur together in Gulf War veterans, and that the investigators sought to investigate an integrated approach. That motivation does not turn the study into a test of comparative effectiveness. With a single group and no control arm, the central interpretable question is whether recruitment and implementation were feasible as recorded, rather than whether the combined intervention caused changes in pain or PTSD.

3. Trial Design

This is a completed, single-group study, with allocation recorded as not applicable and masking listed as none. The study has one intervention group: home-based tDCS combined with Prolonged Exposure Therapy. The registry enrollment field lists 21 participants. The record gives the study start as 2020-01-15 and primary completion as 2021-11-23.

The brief description says the project was intended to integrate and refine home-based tDCS with PE and investigate feasibility in Gulf War veterans with chronic pain and PTSD. It describes an intended group of 15 veterans, whereas the enrollment field lists 21. The registry record does not explain this distinction or specify whether the enrollment field represents a particular analysis population.

The intervention description indicates that participants came to the clinic for a baseline visit and in-person training in home tDCS and the home telehealth device used for PE. The description is truncated before the full intervention schedule is given. Session frequency, total treatment duration, adherence expectations, and procedures for handling changes to the intervention are not reported in the registry record.

The record lists secondary outcome areas related to PTSD, depression, and quality of life, and lists 38 outcome measures. It reports no analyses. The statistical plan, including any planned analysis populations, model specifications, or adjustment strategy, is not reported in the registry record. No comparator is available to separate changes associated with time, assessment, or other influences from changes associated with the combined intervention. Therefore, the design supports descriptive interpretation of feasibility information, but does not establish a controlled treatment effect.

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 Feasibility of Recruitment as Assessed by Number of Participants Enrolled in the Study, measured over Week 0.

The primary endpoint is recruitment feasibility measured by the number of participants enrolled in the study at Week 0. It is a count: it records how many participants entered the study, rather than measuring a change in symptoms or comparing health outcomes between groups.

Recruitment counts are useful in feasibility work because they describe whether a study enrolled participants. Such information can help characterize whether a research approach is practicable to carry forward. A count alone does not show why participants enrolled or did not enroll, how long recruitment took, whether participants completed treatment, or whether the intervention changed health outcomes. Those questions require separate measures and analyses.

The registry enrollment field lists 21. The proposal description states an aim involving 15 Gulf War veterans. The record does not explain the relationship between the stated aim and the enrollment field, and it does not give a separate primary-outcome analysis of recruitment feasibility. Accordingly, the enrollment figure should be read as the registry’s recorded enrollment, not as a reported estimate from a statistical analysis of the primary endpoint.

In general, a count is interpreted in its context: the eligible population, recruitment period, and a prespecified target can matter. Those details, including a recruitment-rate calculation or a formal criterion for success, are not reported in the registry record. The endpoint is relevant to the project’s feasibility purpose, but it does not by itself establish the acceptability, safety, or effectiveness of the treatment approach.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a single-group study with allocation listed as not applicable and masking as none. Those design details matter for interpretation: there is no randomized comparison arm in the record, and the listed intervention is a combination of home-based tDCS and PE. The record does not report a statistical analysis plan. It therefore is not possible to identify a prespecified model, an adjustment strategy, or a planned method for drawing inferences about clinical outcomes.

Counts and recruitment feasibility

The primary endpoint is a count of participants enrolled at Week 0. In general, a count is a direct description of how many participants meet a defined event or status; it is not a continuous symptom score or a treatment-effect contrast. The registry enrollment field lists 21. The record does not report a separate analysis of the recruitment endpoint, a recruitment rate, or a criterion for declaring recruitment feasible. The stated proposal aim of 15 veterans and the recorded enrollment of 21 are distinct details, and the record does not explain their relationship.

Single-group outcome interpretation

In general, a within-group outcome analysis describes how measurements in a group vary over time. Without a concurrent comparator, that description cannot isolate the intervention’s contribution from other influences on outcomes. For example, symptoms may fluctuate, participants may receive other care, and repeated measurement may affect reporting. These are general considerations, not findings about this study. The registry record lists PTSD, depression, and quality-of-life measures, but gives no outcome analyses or estimates of change. Thus there is no reported statistical result to interpret as a within-group change, much less as a causal treatment effect.

Uncertainty and statistical tests

In general, a confidence interval describes a range of values compatible with data and an estimation procedure, and communicates uncertainty around an estimate. A hypothesis test addresses compatibility between data and a specified null model under its assumptions. Neither is a substitute for design: a precise estimate from a single-group study would still not, by itself, provide a controlled estimate of treatment effect. The registry record reports no confidence intervals, test statistics, or p-values for the listed outcomes. Their absence is not evidence of a statistically nonsignificant result; no such analysis is reported in the registry record.

Planning illustrations

The record describes a sample-size illustration based on a stated fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says that time-to-event illustrations use a total event count, while other illustrations use participants per arm. These are planning assumptions, not the design description of this single-group study. No numerical illustration, effect estimate, or inputs for such calculations are reported in the registry record. The illustration cannot be read as an observed result or as evidence of observed power. A calculation based on a hypothetical effect is a planning exercise; it does not establish that the effect occurred or that the actual study had a particular power.

In general, power calculations depend on the effect size being targeted, variability or event frequency, allocation, and statistical assumptions. If the assumed effect is reduced, the required sample size generally increases; if it is increased, the required sample size generally decreases, all else equal. This is a general explanation, not a calculation for this trial. No planning sample size or assumption set specific to the study’s single-group feasibility objective is reported in the registry record.

Event counts and dispersion

The primary endpoint is a count, but the record does not report a count distribution or an inferential model for it. In general, count outcomes can have variation that differs from a simple model’s assumptions. Over-dispersion means that observed variability is greater than a model expects; if ignored, uncertainty estimates can be too small and tests can be misleading. This is a general statistical issue, not a finding in this study. The registry record does not report a model assessment or a dispersion parameter.

Analysis transparency

The record lists 38 outcome measures and reports zero analyses. It does not specify which analysis populations would be used, how missing measurements would be handled, or whether analyses would be adjusted for baseline values or other factors. These details are important because analysis decisions can affect estimates and their uncertainty. In their absence, interpretation should remain limited to the design and descriptive values that the registry actually records, rather than assuming a particular statistical method.

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("Home-based tDCS + Prolonged Exposure Therapy")
n      <- c(21)
events <- c(21)
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  Home-based tDCS + Prolonged Exposure Therapy  21  21  100.0  83.9  100.0  84.5  100.0  84.6  99.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists multiple secondary outcomes addressing PTSD, depression, and quality of life, and reports 38 outcome measures. It does not report analyses. The statistical plan is not reported in the registry record, including whether a primary analysis hierarchy was specified, whether any adjustment for multiple comparisons was planned, or how the listed outcomes relate to each other analytically.

In general, when many outcomes or comparisons are tested, the chance of obtaining at least one apparently unusual result can increase. Multiplicity procedures can help manage that issue, but the appropriate approach depends on the study question and analysis plan. Because there are no reported statistical results or multiplicity methods, there is no basis for judging whether any outcome finding was adjusted, prioritized, or exploratory. The absence of a reported adjustment does not establish that none was planned; that information is not reported in the registry record.

Missing-data methods and analysis populations are also not reported. The record does not state how many participants contributed measurements to each listed outcome, how incomplete assessments were handled, or whether analyses were based on all enrolled participants or a defined subset. The safety fields list 16 participants at risk, while the enrollment field lists 21; the record does not explain the difference. It would be inappropriate to infer a reason for that difference or to treat it as an attrition figure.

In general, missing outcomes can affect both the estimated result and its uncertainty, particularly when the reasons for missingness are related to participant experience or outcome status. A statistical method cannot resolve this concern without information about the missingness pattern and assumptions. Here, no outcome analyses or missing-data procedures are reported in the registry record, so the magnitude and direction of any potential impact cannot be assessed.

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 0% reporting threshold.

The serious adverse-event fields list 16 participants at risk and 0 affected. The other-adverse-event fields also list 16 at risk and 0 affected. Deaths are recorded as 0. These are registry counts, not estimates from a comparative safety analysis.

The listed intervention group is home-based tDCS plus Prolonged Exposure Therapy. No serious adverse-event terms are listed. A recorded count of 0 means that the registry field reports no events for the recorded denominator; it does not establish that an event is impossible, nor does it show how comprehensively events were collected. The record does not provide event definitions, surveillance details, or a narrative explaining the at-risk denominator.

The at-risk count of 16 differs from the enrollment field of 21. The registry record does not explain that difference. It should not be assumed that the safety denominator represents all enrolled participants, or that the difference reflects attrition or a specific analysis population. These counts also should not be interpreted as evidence that the intervention is safe or unsafe. They are descriptive entries whose scope is limited by the information recorded.

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

The record supports a description of a completed feasibility-focused study of home-based tDCS combined with PE in Gulf War veterans with chronic pain and PTSD. It identifies recruitment feasibility, measured by the number enrolled at Week 0, as the primary endpoint. The enrollment field lists 21 participants, and the proposal description states an aim involving 15 veterans. The registry record does not explain the difference between these figures or report a separate statistical analysis of the recruitment endpoint.

The record also lists secondary measures related to PTSD, depression, and quality of life. It reports no analyses, so it does not provide outcome estimates, confidence intervals, or statistical tests with which to assess changes in these domains. The absence of analyses is not evidence that outcomes improved, worsened, or remained unchanged. It means that such results are not reported in the registry record.

The design has no comparator. In general, a single-group study can provide descriptive information about recruitment, implementation, and measured outcomes, but it cannot by itself distinguish intervention effects from other influences. Accordingly, the record does not establish that the combined intervention caused any change in symptoms or quality of life. It also does not provide a comparative estimate of benefit or harm.

The recorded safety fields show 0 serious adverse events and 0 other adverse events among 16 participants listed at risk, with deaths recorded as 0. These counts are limited to the reported fields and denominator. The registry does not explain why the safety denominator differs from the enrollment field, and the counts do not replace detailed safety reporting.

In general, feasibility findings can inform whether a research approach warrants further evaluation, but they do not answer the same question as a controlled treatment-effect study. Here, recruitment and the stated feasibility purpose are central, while detailed feasibility results and clinical outcome analyses are not reported in the registry record. The appropriate interpretation is therefore narrow: the record documents the study design, enrollment field, and selected safety counts, but does not provide statistical evidence establishing treatment effectiveness or a causal safety comparison.

14. Why This Trial Matters Statistically

This study is statistically notable because its stated aim is feasibility, while its primary endpoint is a recruitment count. That distinction matters: feasibility questions concern whether and how a study can be conducted, whereas treatment-effect questions ask whether outcomes differ because of an intervention. A recruitment count can contribute to the former, but it is not a measure of symptom change or a comparison of treatment effects.

The study is recorded as single-group, with no comparator. This makes the design consistent with an exploratory feasibility purpose, but it limits causal interpretation of clinical outcomes. Even if outcome changes had been reported, a single-group design could not isolate the intervention’s contribution from other influences. The registry lists PTSD, depression, and quality-of-life outcome measures, but reports no analyses for them.

The record also illustrates why denominators need context. The enrollment field lists 21 participants, the proposal description states an aim involving 15, and the safety fields list 16 participants at risk. Each number is attached to a different registry entry or description, and the record does not explain how they relate. Treating them as interchangeable would obscure what each field actually represents.

Finally, the absence of reported analyses is important in its own right. It prevents assessment of outcome estimates, uncertainty, missing-data handling, and multiplicity. Statistical interpretation should distinguish clearly between the study’s rationale, its recorded design, and results that are actually reported. The record provides useful design and feasibility context, but does not supply the analyses needed to estimate clinical effects.

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 registry record does not report outcome analyses, although it lists 38 outcome measures. It therefore provides no estimates of change, confidence intervals, test statistics, or p-values for the listed PTSD, depression, and quality-of-life outcomes. The recorded enrollment field is not a substitute for a statistical analysis of the recruitment endpoint.

The design is single-group and has no comparator. This prevents a controlled estimate of treatment effect and limits causal interpretation of any measured changes. The record does not report an analysis plan, outcome-specific methods, or a prespecified hierarchy for the secondary outcomes.

Several details needed to assess feasibility are not reported in the registry record, including recruitment duration, attrition results, intervention adherence, completion of assessments, and a formal criterion for feasibility success. The arm description is incomplete, so the full intervention schedule is not available. The relationship between the proposal’s stated aim of 15 veterans and the enrollment field of 21 is not explained.

The safety fields list 16 participants at risk, compared with 21 in the enrollment field. The record does not explain the denominator difference or describe adverse-event ascertainment in detail. Thus, the safety counts cannot be assumed to cover all enrolled participants.

Missing-data procedures and analysis populations are not reported. Without those details, the completeness and representativeness of any potential outcome data cannot be assessed. Taken together, these limitations mean the registry supports a description of the study’s intent, design, enrollment field, and safety entries, but not a full statistical evaluation of feasibility or clinical outcomes.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Management of Chronic Pain and PTSD in Gulf War Veterans With tDCS+Prolonged Exposure — NCT04236284.
• Registry record last updated 2023-02-03; status last verified 2023-01.
• Results first posted 2023-02-03.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT04236284 is a completed, single-group study of home-based tDCS combined with Prolonged Exposure Therapy in Gulf War veterans with chronic pain and PTSD. Allocation is listed as not applicable, masking as none, and the enrollment field lists 21. The primary endpoint is recruitment feasibility, measured by the number enrolled at Week 0. The proposal description states an aim involving 15 veterans; the registry record does not explain the difference from the enrollment field.

The record lists secondary outcomes related to PTSD, depression, and quality of life, and 38 outcome measures overall, but reports no analyses. Safety fields list 16 at risk and 0 affected for serious and other adverse events, with deaths recorded as 0. The record does not explain the safety denominator or report detailed outcome analyses, missing-data methods, or a statistical analysis plan. It therefore supports a design-level and descriptive reading, not a controlled estimate of treatment effects.