Safety Aid Reduction Treatment for PTSD Among Veterans: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety Aid Reduction Treatment for PTSD Among Veterans (NCT04515784), a na na study. The primary outcome is Change in PTSD Diagnostic Status as Measured by the Clinician Administered PTSD Scale for DSM-5 (CAPS-5).

2. Clinical Question

3. Trial Design

The registry describes an interventional behavioral study with a single-group model and one active arm, START-PTSD. Allocation is listed as NA and masking as none. There is no control group or randomized comparison. This design can describe participants’ measured outcomes over time, but by itself cannot identify what would have happened over the same period without the intervention.

The planned enrollment is 45. The registry lists the study as completed, with a start date of 2023-08-07 and a primary completion date of 2025-09-29. It identifies the VA Office of Research and Development as sponsor. These record details describe the study’s status and design; they do not establish that all enrolled participants completed follow-up or contributed endpoint data.

The stated purpose is to examine acceptability, feasibility, and utility of START among veterans with PTSD. The registry summary hypothesizes that START will be acceptable and feasible and will lead to reductions in PTSD symptom severity immediately and over time. The primary outcome is CAPS-5 change, assessed from baseline to one-month follow-up. Secondary outcomes concern anxiety, depression, PTSD cognitions, and functional impairment. The record lists 8 outcome measures but 0 analyses.

No protocol details beyond the registry information are available in the registry record. In particular, the record does not report a randomized allocation procedure, a comparison treatment, or an analysis plan that would support causal interpretation. The single-group structure is therefore central to reading any change: a before-and-after difference can be described, but it cannot alone show that the intervention caused that difference.

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Analysis population for the primary outcome, as defined in the registry: Subjects lost to follow-up or withdrew/were withdrawn (14); Subjects missing data on CAPS-5 (3)

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 Change in PTSD Diagnostic Status as Measured by the Clinician Administered PTSD Scale for DSM-5 (CAPS-5), measured over One-month follow-up.

The primary endpoint is change in PTSD diagnostic status measured by the Clinician Administered PTSD Scale for DSM-5 (CAPS-5), with a one-month follow-up time frame. The record describes CAPS-5 as a 30-item clinician-administered interview assessing current, meaning past month, and lifetime PTSD diagnostic status. It assesses the 20 DSM-5 PTSD symptoms and includes questions about symptom onset and duration, impairment across life domains, and the dissociative subtype.

For this endpoint, the past month CAPS-5 is to be administered at baseline and one-month follow-up to assess change. The scale’s total scores range from 0-80, with higher scores indicating greater symptom severity. The registry specifies the mean as the outcome parameter and standard deviation as the measure of dispersion. These choices describe a continuous score summary; they do not provide an observed score change or its precision.

CAPS-5 is used to quantify PTSD symptoms and diagnostic status in a structured clinician-administered assessment. Repeated measurement can describe whether scores differ between baseline and follow-up. The registry record does not report the actual scores, the estimated change, or a confidence interval, so the magnitude and precision of any change are not available from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies a continuous primary outcome summarized by a mean and standard deviation. A mean describes the central value of a set of scores, while a standard deviation describes how spread out scores are around that mean. For repeated assessments, change can be represented by comparing baseline and follow-up measurements. The registry specifies this measurement framework, but does not report the values needed to quantify the observed change.

What does a confidence interval communicate?

In general, a confidence interval expresses the precision of an estimated effect: a narrower interval indicates greater precision, while a wider interval indicates greater uncertainty. Its interpretation depends on the analysis and assumptions used. No primary endpoint confidence interval is reported in the registry record, so the precision of the CAPS-5 change cannot be assessed from the registry entries.

What can a single-group change show?

In general, comparing measurements within one group can describe how scores changed between assessment times. Without a concurrent comparator, that comparison cannot isolate the effect of the intervention from other influences over time. Changes in symptoms could reflect the intervention, other care, natural fluctuation, measurement conditions, or differences in which participants provide follow-up data. This is a design limitation, not a defect that can be resolved by a more elaborate calculation on the same single-group data.

What does the analysis listing tell readers?

The record lists 0 analyses. This means the registry record does not contain registered analysis entries for the outcomes described. It does not establish which analyses may have been conducted outside the registry, nor does it reveal whether an analysis plan was followed. The statistical plan, including any model specification, covariate adjustment, handling of repeated measurements, or prespecified testing procedure, is not reported in the registry record.

How should planning illustrations be read?

In general, sample-size calculations are planning tools. The stated assumptions describe an illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The stated effect to detect is a fraction of the observed effect. The assumptions also distinguish total event counts for time-to-event illustrations from participants per arm for other illustrations. These are not the trial’s own design assumptions: the actual study is single-group, and the record does not report a comparator allocation. Such planning figures should not be interpreted as observed power or as evidence that the study could detect a particular effect.

Over-dispersion is a general concern when data vary more than a statistical model assumes. If a model understates variability, standard errors can be too small and intervals can be too narrow. The registry record does not specify a model for the primary endpoint or report variability estimates beyond naming the standard deviation as the dispersion measure. There is therefore no basis in the registry entries to say whether over-dispersion was assessed or relevant to a particular fitted model.

Statistical significance and clinical importance are also distinct concepts in general. A test result addresses compatibility with a statistical null model under specified assumptions; it does not by itself describe the size or practical importance of an effect. Conversely, an estimate needs its uncertainty and context to be interpreted. Since the registry record does not report an endpoint estimate or test, neither statistical significance nor the clinical importance of a change can be determined from it.

The study summary mentions acceptability and feasibility as goals, but the registry entries presented do not define measures or thresholds for those concepts. The primary endpoint is CAPS-5 change, not an explicit acceptability or feasibility measure. The record also does not report a statistical plan for the secondary outcome measures. Any interpretation of those goals would require their operational definitions and results, which are not reported in the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Active Arm- START-PTSD")
n   <- c(28)
m   <- c(27.89)
sp  <- c(11.25)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Active Arm- START-PTSD  28  27.890  11.250  23.528  32.252

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 8 outcome measures, including the primary CAPS-5 outcome and secondary measures of anxiety, depression, PTSD cognitions, and functional impairment. It lists 0 analyses. The record does not report a multiplicity strategy, such as a hierarchy of outcomes or adjustment for multiple comparisons. Without that information, the handling of statistical testing across outcomes is not reported in the registry record. No outcome-specific results or p-values are reported in the registry entries.

The primary endpoint description lists subjects lost to follow-up or withdrew/ were withdrawn (14), and subjects missing CAPS-5 data (3). These are reported categories associated with the endpoint population. The record does not explain whether the categories overlap, when missingness occurred, or the reasons for loss or missing measurement. It also does not specify how missing scores were handled in an analysis, whether any imputation was used, or whether sensitivity analyses were planned.

Missing outcome data can affect interpretation if the participants with observed follow-up differ from those without it. In general, the consequences depend on why data are missing and on the methods used. The registry entries do not provide enough information to judge the direction or size of any resulting bias. The analysis population, inclusion rules, and number contributing to a primary endpoint estimate are not reported in the registry record.

The planned enrollment of 45 should not be treated as the endpoint analysis population. The registry record does not connect the enrollment figure to a reported CAPS-5 estimate or provide a participant flow accounting that resolves follow-up and missing-data categories.

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.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: suicidal ideation (6.7%), suicide attempt (2.2%).

The active arm reports 4 serious adverse events among 45 at risk, with 0 other adverse events and 0 deaths recorded in the listed safety fields. The leading serious adverse event terms are suicidal ideation (6.7%) and suicide attempt (2.2%). These figures are descriptive registry entries; the record does not provide a control group for comparison.

The serious-event count and the percentages attached to named terms should not be added together. A participant may have more than one event or term, and the record does not specify whether the terms overlap. The percentages describe the listed terms as reported; they do not establish causation, comparative risk, or the probability of an event in another setting. The registry record does not report event timing, severity details beyond the serious classification, or attribution to the intervention.

Zero recorded deaths and zero other adverse events refer to those listed safety categories in the registry entry. They do not negate the serious events reported, and they should not be read as evidence that no unlisted event occurred. The one-arm design also means the safety figures cannot establish whether event frequency differs from what would occur without the intervention.

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

The registry describes a completed single-group study of START-PTSD among veterans with PTSD, with CAPS-5 change from baseline to one-month follow-up as the primary endpoint. It also reports serious adverse event entries for the active arm. Those details establish what the study set out to examine and what safety information appears in the record.

The record does not report the primary CAPS-5 results. It therefore does not establish whether scores decreased, increased, or remained similar, nor how precisely any change was estimated. The stated hypothesis of reduced PTSD symptom severity is an expectation, not a posted finding. No conclusion about the intervention’s efficacy or lack of efficacy can be drawn from the absence of endpoint results in the registry record.

Even if a within-group change estimate were available, a single-group design would not by itself distinguish an intervention effect from other changes over time. There is no randomized control arm or like-for-like comparator. The design can support description of observed patterns among participants with data, but not a controlled causal comparison.

The safety information is similarly limited in scope. The serious-event entries indicate that suicidal ideation and suicide attempt were among the named terms, and the listed record includes no deaths. Without a comparison group, event timing, and further attribution details, these entries cannot quantify comparative risk or establish that the intervention caused an event.

The appropriate interpretation is therefore bounded: the registry record documents a behavioral intervention study, a planned CAPS-5 endpoint, missing-data categories, and safety counts. It does not provide the outcome estimates or analysis details needed to judge the magnitude, precision, or cause of change. The record’s completion status should not be mistaken for a report of successful outcomes.

14. Why This Trial Matters Statistically

This study is statistically instructive because it focuses on a clinically relevant repeated measure while using a single-group design. Repeated CAPS-5 assessment can describe change within the group, but without a comparator the observed trajectory cannot isolate the intervention’s contribution. That distinction between description and causal evidence is central when interpreting before-and-after measurements.

The registry also makes the gap between planned enrollment and outcome availability important to notice. It lists enrollment of 45, alongside endpoint-related categories for loss to follow-up or withdrawal and missing CAPS-5 data. The record does not report the analysis population or explain how missing observations were handled. Readers therefore cannot assess whether the endpoint summary, if reported elsewhere, would represent all enrolled participants or a subset with available measurements.

Another statistical lesson is the difference between a study hypothesis and an observed result. The registry states expected acceptability, feasibility, and reductions in symptom severity, but does not provide outcome estimates. A completed study entry and a stated hypothesis do not replace numerical results with uncertainty measures.

Finally, the record’s sample-size assumptions describe a two-arm planning illustration even though the listed study model is single-group. This highlights why planning illustrations must be read in light of the actual design: assumptions about equal allocation and a two-arm comparison do not describe this study’s structure. Overall, careful interpretation requires separating registry status, design, hypotheses, missing data, and reported results rather than treating them as interchangeable evidence.

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 primary limitation for interpreting the posted record is the absence of numerical CAPS-5 results. No baseline or follow-up mean, change estimate, uncertainty interval, or test result is reported in the registry record. Although the study is marked completed, the record does not provide the outcome findings needed to evaluate its stated hypothesis.

The single-group design has no concurrent control arm. Any observed change over time would be difficult to attribute specifically to START-PTSD, because the design does not separate the intervention from other time-related influences. Allocation is listed as NA and masking as none; the record does not describe additional procedures that would address these design constraints.

The endpoint population details identify subjects lost to follow-up or withdrawn and subjects missing CAPS-5 data, but the registry does not explain whether these categories overlap or how missing outcomes were handled. It also does not report the final analysis population. These omissions limit assessment of the representativeness and robustness of any endpoint estimate.

Although secondary outcomes are named, the registry lists 0 analyses and does not report their findings or a multiplicity plan. The statistical analysis plan, model details, and handling of repeated measurements are not reported in the registry record. The stated sample-size assumptions describe a two-arm planning illustration rather than the listed single-group design, so they should not be read as the study’s own design justification.

Safety reporting is limited to the listed counts and serious-event terms. No comparator, event timing, or attribution details are reported. The record therefore supports a descriptive account of those entries, not a comparative safety assessment.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety Aid Reduction Treatment for PTSD Among Veterans — NCT04515784.
• Registry record last updated 2026-10-09; status last verified 2026-09.
• Results first posted 2026-10-09.
• 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 NCT04515784, titled “Safety Aid Reduction Treatment for PTSD Among Veterans,” as a completed behavioral intervention study sponsored by the VA Office of Research and Development. It lists a single active START-PTSD group, planned enrollment of 45, no masking, and no randomized comparison.

The primary endpoint is CAPS-5 change from baseline to one-month follow-up, summarized by a mean and standard deviation. The record describes 8 outcome measures and 0 analyses. It lists endpoint-related categories for loss to follow-up or withdrawal and missing CAPS-5 data, but does not report how these were handled.

Serious adverse events are reported for the active arm, including suicidal ideation and suicide attempt among the leading terms; the listed safety fields report no deaths. Numerical primary outcome results, uncertainty estimates, and a statistical analysis plan are not reported in the registry record.