Group Treatment for PTSD: A Randomized Clinical Trial With Veterans: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Group Treatment for PTSD: A Randomized Clinical Trial With Veterans (NCT01544088), a randomized na study. The primary outcome is Clinician-Administered PTSD Scale for DSM-5 (CAPS-5).

2. Clinical Question

3. Trial Design

The registry record describes a randomized, single-masked, parallel-group clinical trial. Participants were assigned to group cognitive behavioral treatment (GCBT) or present-centered group treatment. The record labels the masking as single, but does not identify which people involved in the study were masked. The trial is listed as completed, with enrollment of 198.

The study summary describes a sample of male veterans with a primary diagnosis of chronic PTSD. Both treatments were planned as 14 weekly sessions. The stated assessment schedule included pretreatment, mid-treatment, post-treatment, and follow-up at 3, 6, and 12 months. The primary outcome reported in the registry is measured at 12 months, so the posted comparison addresses that follow-up rather than the entire course of outcomes across visits.

The posted primary outcome groups are GCBT, with 98 participants and a mean CAPS-5 score of 28.76, and present-centered group treatment, with 100 participants and a mean of 31.87. The reported standard deviations are 13.46 and 14.7, respectively. These are group summaries; they do not show the individual distribution of scores or the amount of change within each participant.

The record gives the study start as 2012-07-01 and primary completion as 2017-08-23. It lists the sponsor as the VA Office of Research and Development. Further details about the randomization procedure, concealment of assignment, masking procedures, recruitment sites, and participant flow are not 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

Analysis population for the primary outcome, as defined in the registry: Primary treatment outcomes were examined using hierarchical linear modeling.

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 Clinician-Administered PTSD Scale for DSM-5 (CAPS-5), measured over 12 months.

The primary endpoint is the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) total score at 12 months. The registry describes the CAPS-5 as a semi-structured interview used to assess the presence and severity of PTSD symptoms. The total score is reported in units on a scale, with a stated range of 0-80; higher scores indicate greater symptom severity.

A clinician-administered symptom measure is used to represent the outcome of interest in a consistent scoring framework. In general, using a defined instrument allows investigators to compare group-level symptom scores at a specified follow-up. It does not, by itself, explain how participants experienced treatment or establish why scores differ.

The registry identifies the mean as the summary measure and the standard deviation as the measure of spread. The mean describes the group’s average score, while the standard deviation indicates how dispersed individual scores are around that average. A group mean is not a score that every participant received, and a difference between group means does not describe each participant’s individual course.

The endpoint is designated as primary, but the registry record does not report a detailed endpoint analysis plan, including a definition of the analysis population or how repeated assessments and incomplete observations were handled. It states that primary treatment outcomes were examined using hierarchical linear modeling, without reporting the model specification or its fitted results.

7. Results Posted in the Registry

• Present Centered Group Treatment: mean 31.87 versus 28.76 on control; difference 3.11 (95% CI -0.81 to 7.03), standardized effect d = 0.22; z-test p = 0.120.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Beck Depression Inventory, II (BDI-II)

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Present Centered Group Treatment: mean 22.29 versus 18.95 on control; difference 3.34 (95% CI -0.26 to 6.94), standardized effect d = 0.26; z-test p = 0.069.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Present Centered Group Treatment and the control. The interval gives the range of effects that remain compatible with the data.

Short-Form Health Survey (SF-36)

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Present Centered Group Treatment: mean 59.05 versus 55.00 on control; difference 4.05 (95% CI -3.74 to 11.84), standardized effect d = 0.14; z-test p = 0.308.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Present Centered Group Treatment and the control. The interval gives the range of effects that remain compatible with the data.

Beck Anxiety Inventory (BAI)

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Present Centered Group Treatment: mean 18.67 versus 15.23 on control; difference 3.44 (95% CI -0.20 to 7.08), standardized effect d = 0.26; z-test p = 0.064.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Present Centered Group Treatment and the control. The interval gives the range of effects that remain compatible with the data.

The three posted secondary outcomes cover depression symptoms, health status, and anxiety symptoms at 12 months. Their group mean differences are all positive under the reported comparator-minus-GCBT direction, so the group averages are higher in the present-centered group across these measures. The confidence intervals for each comparison include zero, and the posted unadjusted p-values do not establish a clear difference on their own. The endpoints have different scales and should not be compared as though a point represented the same quantity across instruments.

The overall direction of the secondary group summaries is consistent with the direction of the primary CAPS-5 mean contrast, but secondary outcomes do not independently confirm the primary result. The endpoints measure related but distinct aspects of symptoms or health, and their results do not replace the primary outcome. Nor does a similar direction across outcomes establish a common underlying treatment effect.

Unadjusted secondary results carry less weight because multiple outcomes create multiple opportunities for apparently notable findings. If many comparisons are considered, some may look unusual even when there is no underlying difference. Whether multiplicity was controlled, and whether the secondary outcomes had a prespecified inferential hierarchy, are not reported in the registry record. The posted p-values should therefore be read as unadjusted rather than as a family-wise assessment across outcomes.

The registry identifies three secondary outcomes and reports no analyses in its analysis listing. As with the primary result, the record gives group summaries and comparison quantities but does not describe a full modeling strategy for these outcomes. No conclusions about the clinical importance of the secondary differences can be drawn from these statistics alone; the registry record does not state meaningful-difference thresholds for them.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Beck Depression Inventory, II (BDI-II)
• Short-Form Health Survey (SF-36)
• Beck Anxiety Inventory (BAI)

9. Statistical Interpretation

10. Statistical Methods Explained

The registry identifies the CAPS-5 outcome as a continuous measure summarized by its mean and standard deviation. These summaries are useful for describing average scores and their variability, but they do not retain all information about the underlying score distributions. A mean difference is a direct expression of the distance between the group averages on the outcome’s original scale. Here, the reported contrast is defined as the present-centered group mean minus the GCBT group mean.

What does the mean difference represent?

The estimate of 3.11 is the observed difference between the posted 12-month group means. Because the outcome is scored so that higher values indicate greater symptom severity, a positive value under this contrast definition means the comparator group’s average is higher than the GCBT group’s average. This is a group-level comparison. It is not the average change from baseline, and it does not imply that all participants had scores in the same direction.

The standard deviations of 13.46 and 14.7 describe variation in CAPS-5 scores within the two groups. They are not standard errors of the group means. A standard error describes uncertainty in an estimate, while a standard deviation describes the spread of observations. The registry also reports standard errors for the means, 1.36 and 1.47. These quantities answer different questions and should not be used interchangeably.

How should the confidence interval be read?

A confidence interval gives a range of values compatible with the data and the statistical procedure used to construct it. In general, it conveys the precision of an estimated contrast: a narrower interval indicates greater precision than a wider interval, all else being comparable. The reported interval for the CAPS-5 mean difference includes zero. Thus, it does not exclude a null mean difference at the interval’s corresponding confidence level. The confidence level itself is not stated in the registry record.

The interval is not a range containing a fixed proportion of individual participant scores, and it is not a probability distribution for the true effect. Its interpretation depends on the analysis assumptions and procedure. The record does not state the confidence-interval method for this comparison, so it is not possible to assess from the registry entry whether it accounts for the stated hierarchical linear model.

What does the p-value contribute?

The unadjusted p-value of 0.12 describes how unusual a result at least as incompatible with a null hypothesis would be under the assumptions of the test, if the null hypothesis were true. It does not measure the size of the treatment contrast, the likelihood that the null is true, or the probability that the finding is due to chance. Interpretation depends on the test and model, and the registry record does not specify those details for the posted p-value.

Because the p-value is labeled unadjusted, it should not be treated as accounting for testing across multiple endpoints or analyses. Whether and how multiplicity was addressed is not reported in the registry record. A p-value also does not measure clinical importance; that requires a meaningful-outcome benchmark, which is not reported for this endpoint.

Why does the stated model matter?

The registry says primary treatment outcomes were examined using hierarchical linear modeling. In general, hierarchical models can represent data that have levels or repeated observations, and can account for dependence among observations when the model is specified to do so. This can be relevant when measurements are collected repeatedly from participants. The registry lists multiple assessment times, but does not describe the hierarchy, covariance structure, time terms, covariates, or estimation procedure. Those details cannot be inferred from the model label alone.

The result presented as a mean difference is an easily read group contrast, but the registry does not establish that it is the estimate from the hierarchical model. No primary model output is listed among the reported analyses. Consequently, the posted summary statistics support a descriptive comparison, while a fuller appraisal of the prespecified or fitted model is not possible from this record.

What is over-dispersion, in general?

Over-dispersion is a general concern for some statistical models when observed variability exceeds what the model assumes. If unaccounted for, uncertainty can be understated and tests can appear more precise than warranted. The primary endpoint is reported as a continuous score with standard deviations, and the registry does not report a model dispersion diagnostic or identify over-dispersion as an issue. It should not be assumed to have occurred in this trial. More generally, model diagnostics and the fit of the analysis are important parts of interpreting an estimate, but the relevant details are not reported in the registry record.

Overall, the posted analysis quantities include group means, standard deviations, a mean difference, a confidence interval, and an unadjusted p-value. The study description additionally identifies hierarchical linear modeling as the approach for primary treatment outcomes. Without a model-specific estimate and analysis details, these items should be kept distinct rather than treated as a complete account of the statistical analysis.

11. Confidence Intervals and Precision

The primary mean difference is 3.11 CAPS-5 points, with a confidence interval from -0.815 to 7.035. This interval spans zero, so the posted result does not rule out a null difference. It also encompasses possible values on either side of zero, meaning that the precise direction and magnitude of the population contrast remain uncertain. The unadjusted p-value is 0.12, which is consistent with the interval’s failure to exclude zero, but the p-value and interval communicate different aspects of the result.

Precision is about the range of effect sizes compatible with the data and the analysis, not simply whether a statistical threshold has been crossed. The interval allows a reader to assess both direction and possible magnitude more directly than a p-value alone. The registry does not state the confidence level or the method used to calculate this interval. It also does not report a model-based interval from the hierarchical linear analysis, so the interval should be interpreted as the one attached to the posted mean-difference comparison, not assumed to be the model’s result.

The group standard deviations, 13.46 and 14.7, show that individual scores vary around their respective means. They do not directly determine the confidence interval in isolation, and they do not show the full score distributions. The record does not report a clinically important difference threshold, so statistical precision cannot be translated into a judgment about clinical importance from these results alone.

Confidence intervals are sensitive to analysis choices and assumptions. Since details about missing observations, analysis populations, and the interval procedure are not reported in the registry record, readers cannot fully evaluate how those choices influence precision. The interval is informative about uncertainty in the posted contrast, but not a substitute for those missing methods details.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total events. They are illustrations based on the observed effect, rather than the trial’s original design calculation. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect set at the stated fraction of the observed effect. The trial’s own original sample-size assumptions are not reported in the registry record.

The 80% power column represents the planned number of participants per arm for a hypothetical study to have an 80% chance of detecting the specified effect under those assumptions, if that effect were the true one. The 90% power column uses a higher target chance of detecting that effect, and therefore generally calls for more participants per arm. These are planning calculations, not observed power; they do not describe the probability that the completed trial detected a true effect.

The rows illustrate planning for 100%, 75%, and 50% of the observed effect. For the primary CAPS-5 comparison, the figures are 323 participants per arm for 80% power and 432 for 90% power when planning for 100% of the observed effect. Planning for 75% gives 574 and 768 per arm, while planning for 50% gives 1,291 and 1,728 per arm. The pattern reflects a general statistical principle: smaller effects are harder to distinguish from random variation and require more participants for the same target power.

These values are conditional on the stated simplified assumptions and the observed effect used as a planning reference. They should not be read as a recommendation for a future study or as evidence that the original trial was designed around these numbers. The original design assumptions, including any allowances or model-based considerations, are not reported in the registry record.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 3.110; pooled standard deviation σ = 14.100.
2. n = 2 × (1.96 + 0.842)² × 14.100² / 3.110² = 322.7, rounded up to 323 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 3.11                      # observed difference in means
sigma <- 14.0999629468322                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1544088)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 323 (80% power), 432 (90% power)
 75% of observed effect: n per arm = 574 (80% power), 768 (90% power)
 50% of observed effect: n per arm = 1,291 (80% power), 1,728 (90% power)
power.t.test: 323.6 
Simulated power at n = 323 per arm: 0.798 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when investigators evaluate more than one endpoint, contrast, time point, or subgroup. As the number of statistical tests grows, the chance of at least one apparently notable result can increase, even if there are no real differences. Common approaches include defining a primary endpoint in advance, specifying a testing hierarchy, or adjusting inference across a family of tests. Which approach was used, if any, is not reported in the registry record.

The registry identifies CAPS-5 at 12 months as the primary outcome and lists three secondary outcomes at 12 months. It gives unadjusted p-values for the posted comparisons. The record does not report a multiplicity adjustment, a hierarchy for interpreting secondary outcomes, or a complete list of planned contrasts across all assessment times. Therefore, the secondary p-values should not be treated as if they were adjusted for the number of outcomes or analyses.

Missing-data handling is also not reported in the registry record. The trial summary lists assessment at pretreatment, mid-treatment, post-treatment, and follow-up, but does not state how missing scores were addressed, whether imputation was used, or what assumptions underpinned any model-based handling. The posted group summaries do not reveal whether every randomized participant contributed to the 12-month analysis.

The record does not identify an intention-to-treat, per-protocol, or other analysis population for the posted results. It also does not provide participant-flow details or explain how treatment discontinuation, missed visits, or protocol deviations were handled. These omissions limit assessment of how closely the reported groups represent the randomized groups and how missing observations may affect the comparison.

Hierarchical linear modeling is named for the primary treatment outcomes, but the model specification is not reported. The registry does not state the covariates, time structure, covariance assumptions, estimator, diagnostic procedures, or whether the posted contrast corresponds to that model. These details, together with the absence of reported analyses, leave important elements of the inferential strategy unclear. The descriptive results remain interpretable as posted summaries, but their relationship to the full planned analysis cannot be established from the registry record.

15. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: psychiatric hospitalization (9.0%), hospitalization due to medical illness (4.0%), general disorders (4.0%), infection disease (3.1%), gi illness (3.1%).

The registry reports serious adverse events affecting 15 of 98 participants in the GCBT group and 22 of 100 participants in the present-centered group. It reports zero other adverse events and zero deaths in each group. These counts describe events recorded during the trial; they do not, by themselves, establish that an event was caused by a treatment. The registry record does not provide information about event timing, severity beyond the serious classification, or the investigators’ assessment of relatedness.

Among the listed serious-event terms, the record gives psychiatric hospitalization as 9.0%, hospitalization due to medical illness as 4.0%, General disorders as 4.0%, Infection disease as 3.1%, GI illness as 3.1%, and Uninary disorder as 2.0%. These are registry labels and percentages. The record does not explain whether event categories overlap, how terms were grouped, or the denominator used for each percentage. The categories should not be added together or interpreted as mutually exclusive.

The safety figures are separate from the symptom-scale results. They provide a limited account of reported adverse events and do not establish comparative safety or causality without further details about ascertainment, event definitions, exposure, and relatedness.

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

The registry results describe average 12-month scores in two randomized group-treatment conditions. The mean CAPS-5 score was 28.76 for GCBT and 31.87 for present-centered group treatment, with a reported mean difference of 3.11 under the comparator-minus-GCBT definition. Because higher CAPS-5 values indicate greater symptom severity, the comparator group’s posted average is higher. The confidence interval includes zero, leaving uncertainty about the direction and size of the population difference.

These findings do not establish that either treatment is effective or ineffective. They do not show that every participant improved, worsened, or had the same response. Group averages can conceal substantial variation among participants, and the record does not provide individual trajectories or the distribution of changes. It also does not provide an estimate of change from baseline in the primary result.

The result is limited to the reported outcome, follow-up, population, and comparison. It concerns male veterans described as having chronic PTSD, and compares two group treatments rather than treatment with no intervention. The registry provides no basis for extending the result to populations or settings not described in the record. The registry also does not state a CAPS-5 threshold for a clinically important difference, so the observed contrast cannot be classified as clinically meaningful or unimportant on the basis of these registry entries alone.

Statistical uncertainty is not evidence that the groups are identical. The interval includes a null difference but also allows differences in either direction. Likewise, the p-value is not the probability that the null hypothesis is true. The posted values describe the data under the comparison and analysis information available, while the study’s stated hierarchical modeling approach is not accompanied by reported model output.

The secondary measures and adverse-event counts add context but do not resolve the primary uncertainty. The secondary comparisons are unadjusted, and key information about multiplicity, missing data, analysis populations, and model specification is not reported in the registry record. Accordingly, the results support a cautious account of the posted group summaries, not a definitive causal or clinical judgment.

17. Why This Trial Matters Statistically

This trial is statistically notable as a randomized comparison between two active group-treatment conditions, rather than a comparison with no treatment. That design makes the estimand a relative contrast between GCBT and present-centered group treatment. The primary result therefore addresses how the groups’ reported 12-month mean CAPS-5 scores compare, not what would have occurred without group treatment.

The registry makes it possible to inspect both the scale-level outcome and uncertainty around the group contrast. The reported mean difference is interpretable in CAPS-5 points, and its interval shows that the data remain compatible with a range of possible differences, including zero. This is a useful reminder that an estimate and its precision should be considered together rather than reducing a result to a single p-value.

The record also illustrates why the analysis method matters. Hierarchical linear modeling is identified for primary treatment outcomes, while the posted result is presented as a group mean contrast without corresponding model output. An analysis label does not reveal its specification or establish that a displayed summary estimate is the model-based result. Clear reporting of model estimates and assumptions would help readers connect the statistical method to the observed outcome.

Finally, the planning illustrations show how design requirements depend on the effect size targeted. Smaller target effects require larger planned samples under the stated assumptions. These illustrations are distinct from the original trial design, whose assumptions are not reported. Taken together, the record offers a concrete setting for considering contrasts, interval precision, multiplicity, and the gap that can exist between a named analysis method and the details needed to evaluate it.

18. 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.

Several trial-specific details needed to evaluate the reported comparison are not reported in the registry record. Although the study is identified as randomized and single-masked, the record does not describe the randomization method, allocation concealment, or who was masked. It also does not provide a participant-flow account or explain how many randomized participants contributed outcome data at each assessment.

The study summary lists repeated assessments, and the registry says hierarchical linear modeling was used for primary treatment outcomes. However, the model specification and its estimate are not reported. The registry does not explain how time was represented, whether baseline scores or other covariates were included, or how within-participant correlation was handled. The posted 12-month comparison therefore cannot be confidently identified as the result of the stated model.

The handling of missing data and the analysis population are not reported. The record does not state whether analyses followed an intention-to-treat approach, how incomplete follow-up was managed, or whether sensitivity analyses were performed. These omissions matter because the posted group summaries alone do not show whether outcome availability differed across groups.

The registry reports unadjusted secondary comparisons but does not describe a multiplicity strategy or hierarchy for interpreting multiple endpoints and assessments. It also does not report a threshold for clinically important differences on the CAPS-5 or secondary measures. As a result, neither the statistical priority of secondary findings nor the clinical importance of the observed mean contrasts can be established from the record.

Finally, the posted safety information does not describe event ascertainment, timing, relatedness, or category overlap. The record’s summary of serious adverse events is therefore descriptive and limited. These reporting gaps do not negate the results that are posted, but they constrain how fully the trial’s analysis and safety findings can be assessed.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Group Treatment for PTSD: A Randomized Clinical Trial With Veterans — NCT01544088.
• Registry record last updated 2020-03-23; status last verified 2020-03.
• Results first posted 2019-04-29.
• 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.

22. Record Summary

NCT01544088 is a completed randomized, parallel-group trial with single masking, comparing group cognitive behavioral treatment with present-centered group treatment for male veterans with chronic PTSD. The registry reports enrollment of 198 and describes both conditions as 14 weekly group sessions.

The primary outcome was mean CAPS-5 total score at 12 months. The posted group means were 28.76 for GCBT and 31.87 for present-centered group treatment. The reported mean difference was 3.11, with a confidence interval spanning -0.815 to 7.035 and an unadjusted p-value of 0.12. The registry states that primary treatment outcomes were examined using hierarchical linear modeling, but does not list model analyses.

Three secondary outcomes are posted, along with serious adverse-event counts. Important details about model specification, missing data, analysis populations, multiplicity, and the trial’s original sample-size assumptions are not reported in the registry record.