Computerized Tailored Intervention for Behavioral Sequelae of PTSD in Veterans: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Computerized Tailored Intervention for Behavioral Sequelae of PTSD in Veterans (NCT01510834), a na na study. The primary outcome is Change in PCL-M Score (PTSD Symptom Checklist-Military [PCL-M], Weathers et al., 1993).

2. Clinical Question

This is principally a development and feasibility project, rather than a controlled test of comparative effectiveness. The project adapted an existing computerized tailored intervention for veterans and included review and integration of programs, adaptation of feedback and multimedia, initial testing, cognitive and usability testing, and a feasibility study. The brief summary describes these sequential project phases, but does not report detailed results for each phase.

The clinical question needs to be interpreted in that context. A within-group change can describe how measured symptoms differed over follow-up among participants with recorded measurements. Without a comparator group, it cannot separate an intervention-associated change from other explanations, such as changes over time or the characteristics of participants who completed follow-up. The registry record does not report the primary outcome estimate needed to describe the observed change.

3. Trial Design

The registry identifies this as a completed, single-group study of the Multibehavioral, Computerized Tailored Intervention STR2IVE. The sponsor is VA Pacific Islands Health Care System. The study start is listed as 2011-07 and primary completion as 2012-03. Phase is listed as NA, allocation as NA, and masking as none. Enrollment is recorded as 90.

The project’s stated purpose was to assess the usability and feasibility of an Internet-delivered, multibehavioral computerized tailored intervention for veterans with post-traumatic stress symptoms. It adapted an existing system based on the Transtheoretical Model of Behavior Change for a veteran population. Its behavioral content addressed smoking, stress management, and depression prevention. The registry summary describes a sequence of development activities, including reviewing existing programs, adapting text and multimedia, initial testing, and cognitive and usability testing with veterans, followed by a feasibility study.

All STR2IVE participants were asked to complete online assessments at baseline, 1-month, and 3-months, and to complete 2 or more behavioral programs each month. The primary outcome timeframe compares baseline (T1) with the final 3 mos. follow-up (T3). The study therefore includes repeated assessment of participants in one group rather than a parallel-group comparison.

The single-group structure is important when interpreting any change over time. Repeated observations can describe the course of measured outcomes in participants, but they do not by themselves establish that the intervention caused a change. No randomized allocation, control arm, or like-for-like comparator is described in the registry record. The protocol’s detailed statistical analysis plan, any sample-size justification, and any interim analyses are not reported in the registry record. The enrollment figure is not, by itself, evidence about the number included in each outcome analysis; the primary outcome description separately identifies 57 participants who completed all time points.

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.

Before assignment: To minimize participant risk, secondary screening excluded veterans who did not meet risk criteria for mild to moderate PTSD (score \<25 or \>73 on the PCL-M), or had severe depression (scoring ≥20 on the PHQ-8). 354 veterans registered on the site, 95 did not complete screening; 169 screened out; 90 completed baseline assessments.

Overall Study

Analysis population for the primary outcome, as defined in the registry: 57 completing all time points for intervention and assessment.

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 PCL-M Score (PTSD Symptom Checklist-Military [PCL-M], Weathers et al., 1993), measured over Change in PCL-M score from baseline (T1) to final 3 mos. follow-up (T3).

The primary endpoint is change in the PTSD Symptom Checklist-Military, or PCL-M, score from baseline (T1) to final 3 mos. follow-up (T3). The PCL-M is a self-report questionnaire consisting of 17 questions that map to DSM-IV criteria for PTSD. Respondents report how often they have been bothered by each symptom in the past month, using a 5-point Likert scale from 1=not at all to 5=extremely.

The endpoint is described as a mean change in score, with standard deviation as the measure of dispersion. The PCL-M score can range from 17-85, and higher scores indicate more PTSD symptoms. Thus, a score reduction from T1 to T3 is a more favorable direction on this measure than an increase. The instrument description notes that a score of 48 typically indicates PTSD in military populations and states thresholds for response and clinically meaningful improvement. Those thresholds give context for interpreting individual change, but the registry record does not report how many participants met them.

A change score is used to express how the measured outcome differs between the specified assessments. Its interpretation depends on the observed average change, variability, and uncertainty, as well as the completeness of follow-up. The registry record does not report the primary mean change, standard deviation, confidence interval, or p-value. Consequently, it is not possible from the registry information to describe the size or precision of the observed primary endpoint result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registered primary outcome is a continuous measure: change in mean PCL-M score from baseline to final 3 mos. follow-up. The registry identifies the mean as the parameter and standard deviation as the dispersion measure. A mean describes the average score or average change in a group. A standard deviation describes how spread out individual scores or changes are around that average; it is not the uncertainty of the mean itself.

What does a mean change represent?

A mean change summarizes the average difference between scores at the specified assessments for the participants included in the analysis. The sign and direction need to be interpreted using the scale’s meaning: higher PCL-M scores indicate more PTSD symptoms, so a reduction is a decrease in reported symptoms on this measure. A group mean can mask variation among individuals, including some participants changing in different directions. The registry record does not report the mean change or the distribution of individual changes.

General statistical explanation: an estimate is more informative when presented with a measure of uncertainty. A confidence interval describes a range of values compatible with the data and the statistical method used, under its assumptions. A narrow interval indicates greater precision than a wide interval. A confidence interval is not a guarantee that the true value falls inside that particular interval. No confidence interval for the primary outcome is reported in the registry record, so its precision cannot be assessed from the registered results.

What role does the standard deviation play?

The standard deviation describes participant-level variability, whereas the standard error and confidence interval concern uncertainty in an estimated group mean. These quantities answer different questions. Larger between-participant variability can make an average change less precise, all else being equal. However, the registry record does not provide the primary outcome standard deviation or the analysis details needed to reconstruct an uncertainty interval. No recalculated estimate is reported.

General statistical explanation: continuous outcome analyses may use methods that compare means or model repeated observations. Repeated-measures methods can account for the fact that scores from the same participant are related over time. The appropriate approach depends on the analysis objective, data structure, assumptions, and missingness. The registry record does not state which method was used, whether the primary analysis used paired changes or a longitudinal model, or how its assumptions were evaluated.

How should a p-value be read?

General statistical explanation: a p-value measures how unusual data at least as inconsistent with a specified null hypothesis would be if that hypothesis and the statistical model were correct. It does not measure the probability that the null hypothesis is true, the size of an effect, or whether a result is important to participants. It should be interpreted alongside the effect estimate, its uncertainty, the analysis plan, and the study design. The registry record does not report a p-value for the primary outcome.

A p-value also cannot remedy limitations of design. In a single-group study, a test of change over time would concern whether the observed within-group change is compatible with a null model of no change under that analysis. It would not establish that the intervention caused a change, because there is no concurrent control group to account for other explanations. Statistical significance and causal interpretation are separate issues.

What is over-dispersion, and does it apply?

General statistical explanation: over-dispersion occurs when observed variability is greater than a statistical model expects. It is particularly relevant for count or binary outcomes analyzed with models that impose a particular variance structure; unmodeled extra variability can make standard errors too small and inference too certain. The primary outcome in this record is continuous, and no evidence of over-dispersion or a model assessing it is reported. It should not be assumed to be an issue for the PCL-M analysis without further information.

The registered secondary outcomes are changes in QOLS, PSS, and PHQ-8 scores from T1 to T3. Considering several outcomes raises the general issue of multiplicity: the more hypotheses tested, the greater the chance that at least one result appears statistically notable by chance if each is interpreted separately. Adjustment strategies and prespecified outcome hierarchies can address that concern, but the registry record does not report a multiplicity procedure or the statistical analysis plan.

The sample-size assumptions refer to an illustrative calculation using a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect set as a stated fraction of the observed effect. Such calculations describe hypothetical planning requirements under those assumptions. They are not observed power, and they do not establish what the study was designed to detect. In particular, equal allocation between two arms is an illustration rather than the registered single-group design. The numerical planning estimates and the protocol’s own sample-size rationale 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("Mean Difference in PCL (T1, T3) (Negative Change i")
n   <- c(57)
m   <- c(-6.82456)
sp  <- c(14.1486)
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  Mean Difference in PCL (T1, T3) (Negative Change i  57  -6.825  14.149  -10.579  -3.070

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary PCL-M outcome and secondary changes in QOLS, PSS, and PHQ-8 scores from T1 to T3. It records 4 outcome measures and 4 analyses. Assessing several outcomes can create multiplicity: if each is tested separately, the chance of at least one apparently unusual result can increase. General statistical approaches include prespecifying a primary outcome, adjusting for multiple comparisons, or treating secondary analyses as exploratory. The registry record does not report whether any such approach was used, nor does it report a statistical analysis plan.

Missing-data interpretation is also important because the primary outcome description specifies 57 participants completing all time points for intervention and assessment, whereas overall enrollment is recorded as 90. These registry entries do not establish how many observations were available at each timepoint or which participants were included in each outcome analysis. The registry record does not report reasons for noncompletion, missing-data patterns, or whether any statistical method was used to address missing measurements.

Restricting analysis to participants with complete assessments can be straightforward to describe, but the resulting group may differ from those without complete measurements. General statistical explanation: when the likelihood of missing data is related to participant characteristics or outcomes, complete-case results may not represent all enrolled participants. The extent and direction of any such concern cannot be judged without information about missingness and the analysis method.

The registry does not report whether the primary analysis followed an intention-to-treat principle, used only complete cases, or used another analysis population. Beyond the description of 57 participants completing all time points, analysis populations are not reported in the registry record. No number of missing observations or participant-level disposition can be inferred from the available information.

12. Safety Results

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

Other (non-serious) adverse events

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

The registry records serious adverse events for an all-participant group, with 90 at risk and 0 affected. For other adverse events, it also records 90 at risk and 0 affected. These figures describe the entries in the registry record; they do not establish that no adverse events of any kind occurred outside the recorded categories or collection process.

The deaths field is not reported in the registry record. The record does not provide event definitions, severity criteria, timing, exposure duration, or a narrative description of how safety information was collected. It also does not report a comparator group. Accordingly, the entries cannot support a relative safety comparison between treatments or groups.

General statistical explanation: an observed count of zero is not proof that an event is impossible or that the underlying risk is exactly zero. Its interpretation depends on the completeness of follow-up, event ascertainment, and the amount of exposure observed. The registry figures should therefore be read as reported event counts in this study, not as a definitive estimate of safety for other settings or populations.

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

The registry record identifies an online, multibehavioral intervention project for veterans with post-traumatic stress symptoms. Its primary outcome was designed to describe change in PCL-M score between baseline and final 3 mos. follow-up. The record also identifies secondary measures of quality of life, perceived stress, and depression symptoms. These details explain what the project set out to assess, but the outcome estimates themselves are not reported in the registry record.

Without a reported primary mean change, standard deviation, confidence interval, or p-value, the size, direction, and precision of the observed PCL-M result cannot be described from this record. The same limitation applies to the listed secondary outcomes: their measure names and timeframes are recorded, but their results are not reported. The registry information therefore does not establish whether scores changed or how consistently they changed across participants.

Even if a within-group score change were reported, the single-group design would not show how that change compares with what might have happened without the intervention. Changes over time can have multiple explanations, and the design has no concurrent comparator to distinguish among them. A within-group before-and-after result is not equivalent to a randomized treatment effect.

The project is described as assessing usability and feasibility and adapting a computerized intervention for a veteran population. Those aims differ from establishing comparative efficacy. The record describes a sequence of development and testing activities, but does not report detailed measures or results for usability, feasibility, or each project phase. It is therefore not possible to characterize those findings from the registry information.

The recorded adverse-event counts are limited to the registry entries: 0 serious events affected among 90 at risk, and 0 other adverse events affected among 90 at risk. The record does not report a deaths figure. These counts do not provide a comparative safety estimate and should not be interpreted beyond the recorded follow-up and reporting.

Overall, the registry defines a research question and the measures used to address it, but its available result information is insufficient to describe the primary or secondary outcome findings. It should not be read as evidence that the intervention did or did not produce a particular clinical effect.

14. Why This Trial Matters Statistically

This trial is statistically notable for the distinction between a feasibility-oriented, single-group project and a controlled comparison. The record describes adaptation, initial testing, cognitive and usability testing, and a feasibility study for a computerized tailored intervention delivered online. Those activities can address whether an intervention is developed and assessed in its intended population, but they do not by themselves estimate comparative treatment effects.

The repeated assessment schedule—baseline, 1-month, and 3-months—makes measurement over time central to the project. The primary endpoint uses the baseline and final 3 mos. follow-up PCL-M scores. Repeated measures can describe change within participants, while the absence of a comparator limits causal interpretation. This distinction is useful when reading any numerical result from a one-group design: the statistic may quantify change, but its design does not establish what would have happened otherwise.

The record also illustrates the importance of separating enrollment from the analysis population. Enrollment is 90, while the primary outcome description identifies 57 completing all time points. Those are meaningful but distinct registry entries. Without the analysis plan, missing-data information, and outcome estimates, readers cannot determine how the complete-timepoint population relates to the primary analysis or how precise its estimate is.

Finally, outcome multiplicity and reporting completeness matter. The registry lists a primary measure and additional quality-of-life, stress, and depression measures, but does not report the estimates or a multiplicity approach. The statistical interpretation depends not only on what was measured, but on how outcomes were analyzed, how missing measurements were handled, and how uncertainty was quantified. Those analysis details are not reported in 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 central limitation for interpreting outcomes is that the registry record does not report the primary or secondary outcome estimates. It identifies a mean PCL-M change as the primary outcome and gives the assessment timeframe, but provides no mean change, standard deviation, confidence interval, or p-value. Results for QOLS, PSS, and PHQ-8 are also not reported in the registry record.

The single-group design has no randomized comparator. It can describe measurements over time among participants with recorded outcomes, but cannot isolate intervention effects from other influences. Allocation is listed as NA, and masking as none. The record therefore does not support a like-for-like comparison with another group.

Enrollment is recorded as 90, while the primary outcome population is described as 57 completing all time points for intervention and assessment. The registry record does not report reasons for incomplete follow-up, the number with observations at each individual timepoint, or how missing values were addressed. It does not specify the analysis population or whether the analysis included participants without complete follow-up.

The registry does not report a detailed statistical analysis plan, sample-size justification, or interim analyses. It also does not report whether multiplicity was addressed across the listed outcomes or which statistical methods and assumptions were used. These omissions limit assessment of analysis choices and precision.

The study’s stated emphasis on usability and feasibility and its development phases are described in the brief summary, but detailed phase-specific results are not reported in the registry record. Safety interpretation is also limited: serious and other adverse-event counts are recorded, but definitions, ascertainment details, timing, and a deaths figure are not reported. These limitations concern what can be concluded from the registry information, not a judgment about the conduct of the study.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Computerized Tailored Intervention for Behavioral Sequelae of PTSD in Veterans — NCT01510834.
• Registry record last updated 2017-12-07; status last verified 2013-07.
• Results first posted 2013-07-04.
• 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

NCT01510834 is a completed, single-group study sponsored by VA Pacific Islands Health Care System. Enrollment is recorded as 90. The study start is listed as 2011-07 and primary completion as 2012-03. Phase and allocation are listed as NA, and masking as none.

The project assessed usability and feasibility of an online multibehavioral computerized tailored intervention for veterans with post-traumatic stress symptoms. Participants were asked to complete online assessments at baseline, 1-month, and 3-months and to complete 2 or more behavioral programs each month. The primary measure was change in PCL-M score from baseline to final 3 mos. follow-up. The primary outcome description identifies 57 participants completing all time points for intervention and assessment.

The registry record does not report the primary or secondary outcome estimates, the detailed statistical analysis plan, or missing-data methods. It records 0 serious adverse events affected and 0 other adverse events affected among 90 at risk; a deaths figure is not reported in the registry record.