Developing an Online Therapeutic Intervention for Chronic Pain in Veterans: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Developing an Online Therapeutic Intervention for Chronic Pain in Veterans (NCT03655132), a randomized na study. The primary outcome is System Usability Scale (SUS).

2. Clinical Question

The study concerns the usability of an online intervention, rather than a primary test of whether the program changes pain or functioning. The registry describes Acceptance and Commitment Therapy for Chronic Pain as an approach focused on behavior change in keeping with personal values, and identifies the intervention as a behavioral program. It also lists pain-related and acceptance-related measures among the secondary outcomes.

The primary endpoint is explicitly limited to the VACT-CP group at post-intervention, at 8 weeks. Consequently, the result describes the usability scores of the participants who used the online program and completed the survey. It does not estimate a difference in usability between VACT-CP and waitlist, and it does not by itself estimate an effect of the intervention on pain or other clinical outcomes.

3. Trial Design

The registry record identifies NCT03655132 as a completed, randomized, parallel-group study of an online therapeutic intervention for chronic pain in Veterans. It lists enrollment as 42 and the phase as NA. The study start date is 2022-03-17, and primary completion is recorded as 2023-05-30. The intervention is named Veteran Acceptance and Commitment Therapy for Chronic Pain (VACT-CP).

Participants were assigned to VACT-CP or a waitlist control group. The VACT-CP description specifies 7 weekly online-module-based sessions, delivered through a personal computer or a provided tablet with wireless accessibility at the Bedford VAMC. The waitlist group was provided with a list of common pain resources at the Bedford VAMC. The record identifies the allocation as randomized, the model as parallel, and masking as none. Details of the randomization procedure and any allocation concealment are not reported in the registry record.

The primary outcome was the System Usability Scale (SUS), assessed post-intervention at 8 weeks for the VACT-CP group only. Although the record lists the waitlist group as a trial arm, it reports no waitlist value for this endpoint. The posted primary result therefore concerns the intervention group’s usability score, not a between-group treatment contrast.

The registry lists 8 outcome measures and 16 analyses. Six secondary outcomes are named: the Pain Outcomes Questionnaire - VA, the Chronic Pain Acceptance Questionnaire, the Multidimensional Experiential Avoidance Questionnaire, the Chronic Pain Values Inventory, the Pain Numeric Rating Scale, and the Client Satisfaction Questionnaire-8. The record does not report a protocol-level sample-size justification or detailed information about recruitment, follow-up schedules for all measures, or analysis populations beyond the primary outcome description.

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: Usability scores only reported for participants randomized to VACT-CP group only, i.e., using the online program who completed the Week 7 survey, n = 17 (due to 1 participant withdrawn prior to using VACT-CP program and 2 LTF).

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 System Usability Scale (SUS), measured over Post-Intervention, at 8 weeks for VACT-CP group only.

The primary endpoint is the System Usability Scale (SUS), a 10-item measure of human-computer interaction. Its items use a 5-point Likert scale from Strongly Disagree (1) to Strongly Agree (5). The scoring method reverses the contribution of alternating items, sums the item contributions, and multiplies that sum by 2.5 to produce an overall score from 0 to 100. Higher scores indicate greater system usability.

The SUS is used to capture users’ subjective assessment of how usable a system is. In this study, it addresses whether participants who used VACT-CP found the online program usable after the intervention. The registry describes scores above 58 as above average and scores above 80 as high, with the latter described as a level above which participants are likely to recommend the product to friends. These reference points do not replace the study’s own observed data or establish how any individual participant responded.

The reported endpoint is the mean SUS score and standard deviation for VACT-CP participants who completed the Week 7 survey. It is not reported for the waitlist group. The result is therefore a descriptive usability summary among respondents, rather than a randomized comparison or an assessment of changes in pain, daily functioning, or other clinical outcomes.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean and standard deviation describe?

For a continuous measure such as the SUS, the mean is the arithmetic average of the observed scores. It gives a compact description of the group’s central result, but it does not show the full distribution. Different sets of participant scores can have the same mean while differing in their spread or shape.

The standard deviation describes how dispersed scores are around the mean. A larger standard deviation indicates more variability in scores within the group, while a smaller one indicates that scores are more clustered. It is not the same as a confidence interval and is not a measure of uncertainty about the mean. The posted result gives a mean of 79.6 and a standard deviation of 12.8 for 17 participants.

What would a confidence interval add?

General statistical explanation: a confidence interval expresses uncertainty around an estimate under a specified statistical procedure and assumptions. For a mean, it can help readers judge how precisely the sample average estimates a broader population average. The registry record does not report a confidence interval for the SUS mean, so the precision of that estimate cannot be assessed from an interval in the posted primary result. A standard deviation alone cannot substitute for that interval.

Why does the endpoint population matter?

The SUS result applies to VACT-CP participants who completed the Week 7 survey, rather than to both randomized groups. The endpoint description identifies 17 respondents and notes 1 participant withdrew before using the program and 2 LTF. A result among survey respondents can be affected by who did and did not contribute data, especially if their experiences differ. The registry record does not report enough detail to determine whether missingness was related to usability or how missing endpoint data were handled analytically.

Because the waitlist group has no posted SUS value, no between-group mean difference can be estimated from this endpoint. Randomization can support comparisons when outcome data are collected and analyzed for the randomized groups, but it does not create a comparator result where none is posted. The reported usability summary should therefore be interpreted as descriptive for VACT-CP respondents, not as a randomized estimate of an intervention effect.

What is the role of the SUS thresholds?

The measure description provides reference points: scores above 58 are regarded as above average, and scores above 80 as high. Such thresholds may help contextualize SUS scores, but they are not statistical tests and do not indicate the precision of the group mean. A group average also does not tell how many individuals cross a threshold. To assess that, the distribution or participant-level results would be needed; those are not reported in the registry record.

How should planning calculations be understood?

General statistical explanation: sample-size calculations for a future study depend on a chosen effect to detect, the assumed variability, the significance level, allocation, and the statistical model. The registry record describes planning illustrations based on fractions of the observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such illustrations are planning scenarios, not a measure of the probability that this completed study found a true effect. They do not establish that the study was designed with a particular sample-size justification; that justification is not reported in the registry record.

The record does not provide numerical planning results in the registry record for this account, so no specific target sample size can be interpreted. Any planning illustration based on an observed effect is also dependent on the assumptions used to construct it. It should not be confused with the number of participants enrolled or with observed power.

Why do multiplicity and analysis choices matter?

The registry lists 8 outcome measures and 16 analyses. When multiple outcomes or analyses are considered, the chance of at least one apparently unusual result can increase if each is treated as a separate test without adjustment. Methods such as family-wise error control or false-discovery-rate procedures can address different multiplicity goals. Which outcomes were grouped together, whether testing was confirmatory or exploratory, and whether any multiplicity adjustment was used are not reported in the registry record. The counts alone do not show that any particular adjustment was necessary or performed.

More broadly, interpretation depends on the prespecified analysis population, handling of missing observations, model assumptions, and whether the endpoint analysis was planned in advance. These details are not reported for the primary usability result. Given the descriptive endpoint and absence of a comparator score, the central statistical reading rests on the observed mean, standard deviation, and the limited respondent population, rather than on an unreported inferential test.

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("VACT-CP Group")
n   <- c(17)
m   <- c(79.6)
sp  <- c(12.8)
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  VACT-CP Group  17  79.600  12.800  73.019  86.181

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 8 outcome measures and 16 analyses, including the primary SUS endpoint and six named secondary outcomes. Assessing many outcomes or analyses can raise multiplicity concerns when results are interpreted through repeated statistical tests. A prespecified hierarchy, correction method, or clear distinction between confirmatory and exploratory analyses can help readers understand how to interpret multiple findings. Such details are not reported in the registry record. The counts do not reveal which results were tested together or whether any adjustment was used.

The primary usability summary is available for 17 VACT-CP participants who completed the Week 7 survey. The outcome description notes 1 participant withdrew before using VACT-CP and 2 were recorded as LTF. The record does not report a detailed missing-data method, an imputation approach, or a sensitivity analysis for the SUS endpoint. It also does not explain whether missingness was considered related to participants’ usability experiences.

The endpoint population is therefore a respondent group, not all participants enrolled or randomized. If participants without usability results had systematically different experiences, the observed mean might not represent the full intervention group. The posted information does not allow that possibility to be evaluated. A comparison of included and missing participants, along with the prespecified analysis population and missing-data plan, is not reported in the registry record.

The waitlist group has no reported SUS value, so the primary endpoint cannot be used to estimate a between-group difference. Details of the analysis plan, including any planned comparison for other outcomes, are not reported in the registry record. The available primary result should be interpreted as a descriptive summary for VACT-CP survey respondents, with no reported multiplicity adjustment or missing-data sensitivity analysis to qualify it further.

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 registry reports serious adverse event figures for 22 participants at risk in the waitlist control group and 20 in the VACT-CP group. Serious adverse events affected 0 participants in each group. The record also reports 0 deaths in each group. These are the posted serious-event and death counts; they do not establish that no events of any kind occurred.

The record separately lists 22 participants at risk for other adverse events in the waitlist group and 20 in VACT-CP, with 0 affected in each group. No top serious adverse event terms are listed. The safety counts should be read as registry-reported counts over the period captured by the record. The duration and completeness of adverse-event monitoring are not reported in the registry record.

Zero reported events in these groups is a descriptive observation, not proof that an event is impossible or that risks are identical between groups. The figures do not provide a comparative statistical analysis or an estimate of how precisely event rates are known. They also do not establish safety in populations or settings beyond the participants and observation covered by this trial.

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

The primary result describes reported usability among VACT-CP participants who completed the Week 7 survey. Their mean SUS score was 79.6, with a standard deviation of 12.8, for 17 participants. This offers a summary of how the responding participants rated the online program on a measure designed to assess human-computer interaction.

The result does not show a randomized difference in usability, because the registry does not report a SUS score for the waitlist group. It also does not answer whether the online intervention improves chronic pain or related functioning. Those questions require their relevant outcome results and an analysis suited to the comparison being made. The registry lists pain-related and other measures as secondary outcomes, but numerical findings for those measures are not included in the registry record for this account.

The summary does not report individual scores, a confidence interval, or a hypothesis test for the mean. It therefore cannot establish how precisely the average represents a wider population, how varied participants’ experiences were beyond the standard deviation, or how many participants reached a particular SUS reference threshold. The fact that respondents provided usable data also does not establish that all participants would have had the same experience.

The record says usability results are limited to VACT-CP users who completed the Week 7 survey, and notes 1 participant withdrew before using the program and 2 LTF. The registry does not report a detailed missing-data analysis or reasons that would allow the potential effects of missingness to be assessed. The sample mean should therefore be understood as applying to the reported respondents.

The appropriate conclusion is bounded: the registry reports a mean SUS score of 79.6 and a standard deviation of 12.8 among the 17 VACT-CP survey respondents. This is descriptive evidence about usability in that group. It does not, by itself, establish comparative usability, clinical effectiveness, or a conclusion about all Veterans with chronic pain.

14. Why This Trial Matters Statistically

Usability is an important statistical and practical question for an online behavioral intervention because a program’s content can only be engaged with if participants can use its system. The SUS captures participants’ subjective assessment of that human-computer interaction. Reporting a group mean alongside a standard deviation gives readers both a central summary and an indication of variation among those who responded.

This study’s endpoint also illustrates why the population behind an estimate matters. The SUS result is reported only for VACT-CP participants who completed the Week 7 survey. It is not a randomized contrast with waitlist, and the endpoint description notes participants without usability results. A transparent distinction between respondents and the randomized groups helps prevent a descriptive usability result from being read as a treatment effect.

The registry record names several secondary outcomes and reports counts of 8 outcome measures and 16 analyses. This highlights the importance of knowing which questions were primary, how multiple analyses were handled, and whether missing data were addressed according to a prespecified plan. Those statistical details are not reported in the registry record for this account. Their absence limits how fully readers can evaluate confirmatory claims or the robustness of results across outcomes.

The posted mean of 79.6 and standard deviation of 12.8 are useful descriptors, but they cannot stand in for uncertainty intervals, individual score distributions, or comparative analyses. These distinctions matter when a usability measure is interpreted alongside clinical outcomes. A usability score addresses user experience; it does not demonstrate that pain or other health-related outcomes changed.

Statistically, the study illustrates the value of matching the claim to the outcome, analysis population, and available comparison. The primary result can inform a focused description of usability among respondents, while its design and reported data do not support broader claims about comparative usability or 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 main limitation for interpreting the primary endpoint is that it is reported for the VACT-CP group only. No waitlist SUS value is posted, so the endpoint cannot support a randomized comparison of usability between groups. It is also a subjective usability measure, not a direct measure of pain improvement or functional change.

The result is based on 17 participants who completed the Week 7 survey. The registry notes 1 participant withdrew before using VACT-CP and 2 were recorded as LTF, but does not report a detailed analysis of missingness or the characteristics and experiences of those without scores. This limits assessment of whether the reported respondents represent all those assigned to VACT-CP.

The posted primary summary gives a mean of 79.6 and standard deviation of 12.8 but does not include a confidence interval, participant-level results, or a reported inferential test. Precision and the distribution of scores therefore cannot be evaluated fully. The registry’s SUS thresholds provide context but do not resolve those limitations.

The registry lists multiple outcome measures and analyses, but the statistical plan, prespecified hierarchy, and any multiplicity adjustment are not reported in the registry record. A protocol-level sample-size justification, detailed randomization procedures, and further analysis-population details are also not reported in the registry record. These limitations make it difficult to determine how completely the posted summary reflects the planned analyses or how results across outcomes should be interpreted together.

The study record describes one particular online intervention and a waitlist condition that received common pain resources at the Bedford VAMC. Details needed to assess applicability across other delivery settings or groups of Veterans are not reported in the registry record. The limitations do not negate the descriptive result, but they define its scope: usability among the reported VACT-CP respondents at the stated assessment point.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Developing an Online Therapeutic Intervention for Chronic Pain in Veterans — NCT03655132.
• Registry record last updated 2026-07-21; status last verified 2026-06.
• Results first posted 2024-09-19.
• 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

NCT03655132 is a completed randomized, parallel-group study titled “Developing an Online Therapeutic Intervention for Chronic Pain in Veterans.” The registry lists enrollment as 42, phase as NA, and no masking. The intervention was Veteran Acceptance and Commitment Therapy for Chronic Pain (VACT-CP), described as 7 weekly online-module-based sessions. The waitlist group received a list of common pain resources at the Bedford VAMC.

The primary outcome was the System Usability Scale at post-intervention, at 8 weeks, for the VACT-CP group only. The posted result is a mean of 79.6 and a standard deviation of 12.8 among 17 participants who completed the Week 7 survey. The registry notes 1 participant withdrew before using the program and 2 LTF. No waitlist usability result is reported.

The record lists 8 outcome measures and 16 analyses, including six named secondary outcomes. It reports 0 serious adverse events and 0 deaths in each group. The record does not report the primary endpoint’s confidence interval, a between-group SUS comparison, or detailed methods for multiplicity and missing data.