An Evaluation of MBSR and CBT for Veterans With Chronic Pain: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for An Evaluation of MBSR and CBT for Veterans With Chronic Pain (NCT04486066), a randomized na study. The primary outcome is Pain Interference Subscale of Brief Pain Inventory (BPI).

2. Clinical Question

The question is relevant to non-pharmacologic approaches because the registry background describes chronic pain as often occurring alongside other life problems, including depression and posttraumatic stress disorder, and notes concerns about opioid-related harm. Those statements explain the trial’s rationale; they are not findings from this comparison. The record identifies the study as completed, but completion alone does not establish what the outcome results were or whether any group differed. No clinical conclusion about the relative effects of MBSR, CBT-CP, or usual care can be drawn from the outcome information recorded.

3. Trial Design

This was a randomized, parallel-group trial with no masking. The registry reports 217 participants enrolled and identifies three groups: MBSR, CBT-CP, and usual care. The listed phase is NA. The sponsor is the VA Office of Research and Development. The study start date is 2021-01-27, the primary completion date is 2024-05-01, and the status is completed.

In the MBSR group, participants met in a video group format for 2 hours per week for 8 weeks. The program included mindfulness meditation instruction according to a standardized curriculum, daily homework, group discussions, and opportunities to ask questions. CBT-CP is described as a chronic-pain-focused version of cognitive behavioral therapy developed for use in VA with Veterans. The registry description is cut off before giving a full account of its approach or delivery. Participants assigned to usual care continued with their usual providers for medical and mental health care; the record notes that this could include medications, specialty referrals, and other usual elements of care.

The outcome schedule includes baseline, immediate post-treatment, and 6 months after completing treatment. The primary outcome is the Brief Pain Inventory Short Form Interference subscale. The record says that some participants did not complete post-treatment and 6-month follow-up assessments. It also says that means in the registry reflect participants with complete data, while the main analyses intended for publication are described as intent-to-treat. The actual publication analyses are not reported in the registry record.

Randomization describes how participants were assigned, but the registry information does not state the sequence-generation method, allocation concealment procedures, or the planned analysis model. Masking is listed as none. Further details about implementation, adherence, treatment attendance, and crossover are not reported in the registry record. The outcome information does not reduce the multiple assessment times and groups to a single comparison, so it does not provide a result that can be interpreted as a direct estimate of one intervention’s effect against another.

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: Some participants did not complete the post-treatment and 6-month follow-up assessments. The main analyses that will be shared in publication are intent-to-treat but the means below reflect only those with complete data.

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 Pain Interference Subscale of Brief Pain Inventory (BPI), measured over Baseline, Immediate post-treatment, 6 months after completing treatment.

The primary endpoint is the Pain Interference Subscale of the Brief Pain Inventory Short Form. It is a 7-item measure of how much pain interferes with activities in daily life. The listed domains include general activity, mood, walking ability, work, relationships with other people, sleep, and enjoyment of life. Scores range from 0 to 10, with higher scores indicating greater pain interference.

This measure focuses on the impact of pain on functioning rather than pain intensity alone. That makes it relevant to a trial whose stated aim is to evaluate approaches intended to improve functionality and quality of life for people with chronic pain. The registry specifies that the outcome is reported as a mean with standard deviation. The outcome schedule covers baseline, immediately after treatment, and 6 months after completing treatment, allowing the planned assessment to include more than one point in time.

The record does not report the mean scores, standard deviations, or group comparisons at those assessments. It also does not report a threshold for interpreting a score change as clinically important. Consequently, the measure’s scale and direction can be described, but the degree of change or its practical importance cannot be assessed from the registry outcome entry. The record notes that the posted means reflect participants with complete data, despite describing intent-to-treat analyses as the main analyses that will be shared in publication.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Random allocation means participants are assigned to study groups by a chance-based process rather than by their own choice or a clinician’s selection. In general, randomization is used to reduce systematic differences between groups at the start of a trial. It does not guarantee that groups are identical in every respect, and it does not by itself determine how outcomes should be analyzed. The registry identifies this trial as randomized and parallel, but the exact randomization procedure and allocation concealment approach are not reported in the registry record.

A parallel-group design assigns participants to a group and follows those groups over the study period. Here, the listed groups are MBSR, CBT-CP, and usual care. The record says masking was none. In general, masking can reduce the influence of expectations or knowledge of assigned treatment on some aspects of treatment delivery, outcome reporting, or assessment. In a behavioral program, participants know which activities they attend; the record does not describe any separate masking procedures for assessors or analysts.

The primary outcome is continuous: it is a score on a scale, summarized in the registry as a mean and standard deviation. A mean describes the central value of a set of scores, while the standard deviation describes how dispersed individual scores are around that mean. In general, a group mean alone does not show the distribution of individual experiences, and a standard deviation is not the uncertainty in the estimated mean. To assess uncertainty in a group comparison, readers would usually look for an effect estimate and a confidence interval, or another inferential analysis. Those outcome statistics are not reported in the registry record.

The Brief Pain Inventory Short Form Interference subscale is measured at baseline, immediately after treatment, and 6 months after completing treatment. Repeated assessments can be analyzed in different ways. In general, an analysis might compare groups at a particular follow-up, compare changes from baseline, or model observations across time. These approaches answer related but not identical questions and can rely on different assumptions. The specific analysis model, contrast definitions, and handling of repeated measurements are not reported in the registry record. The outcome listing includes multiple groups and assessment times, and the record does not reduce them to a single comparison.

A confidence interval, when reported, gives a range of values compatible with the data under the statistical model and conveys precision as well as the estimated effect. A narrow interval generally indicates greater precision than a wide interval, while an interval that includes values on both sides of no difference may leave the direction or magnitude uncertain. This is general statistical interpretation, not a description of a trial-specific interval: no confidence interval for the primary outcome is reported in the registry record. Similarly, a p value is a measure of how surprising data would be under a specified null model, given the model’s assumptions. It does not quantify the probability that a treatment works, and no primary-outcome p value is reported.

The registry states that the primary outcome means reflect only participants with complete data, while the main analyses intended for publication are intent-to-treat. In general, a complete-case summary uses only participants with observed measurements at the relevant assessment. An intent-to-treat analysis aims to retain participants in the groups to which they were randomized, even if they did not complete treatment or follow-up, but the exact approach to missing measurements depends on the analysis plan. The registry does not report the missing-data method used for the intended publication analyses, the number of missing assessments at each time, or assumptions about why data are missing. Therefore, the label intent-to-treat cannot reveal how the missing values were treated in the actual analysis.

The registry also includes a sample-size-assumptions statement describing planning illustrations based on an observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says that the effect to detect is a stated fraction of the observed effect and that participant counts in non-time-to-event illustrations are per arm. Such illustrations are not observed power and are not evidence that an effect was found. The actual illustration outputs are not stated in the record information used for this explanation, and no trial-specific sample-size justification or design assumptions beyond that statement are reported in the registry record. It would be inappropriate to infer the trial’s original sample-size rationale from the illustration description.

Over-dispersion is a general statistical concept in which observed variability exceeds what a model assumes. It matters because a model that understates variability can make estimates appear more precise than they are. The primary outcome is a continuous score, and the registry does not report use of a count model or any analysis addressing over-dispersion. More broadly, readers should match statistical explanations to the outcome type and reported model rather than assume a method that the registry does not identify.

Finally, the safety counts are descriptive event summaries. In general, counts can help readers see how many participants had events in each group, but a formal comparison requires a defined method and must account for the amount of follow-up and uncertainty in sparse events. The registry gives group-specific numbers at risk and affected for serious and other adverse events, but does not report a comparative safety analysis. No effect estimate or uncertainty interval for between-group safety differences is reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is assessed at baseline, immediately after treatment, and 6 months after completing treatment, across three study groups. That creates multiple possible group and time comparisons. The registry record does not identify one primary contrast among these possibilities, report a multiplicity adjustment, or describe a hierarchy of hypotheses. It therefore does not show how the risk of false-positive findings across multiple comparisons was handled. The record’s note that the primary outcome has several categories or time points and was not reduced to one comparison is important: no single contrast should be treated as the definitive result based on this entry.

The registry says that some participants did not complete post-treatment and 6-month follow-up assessments. It states that the means in the outcome entry reflect participants with complete data, while the main analyses intended for publication are intent-to-treat. The analysis method for those intended analyses, the extent of missingness at each assessment, and the assumptions used to handle missing observations are not reported in the registry record. Without those details and the actual results, readers cannot evaluate whether the reported complete-data means would differ from the planned analysis or assess the robustness of findings to missing data.

The registry lists one outcome measure and no analyses in its record summary. No prespecified statistical analysis plan, interim analysis details, or adjustment strategy is reported in the registry record. This does not establish that such procedures were absent from other study documents; it means they cannot be assessed from this record. The distinction matters because a reported outcome can have different interpretations depending on whether comparisons and analysis choices were planned in advance or selected after seeing results.

11. 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: hospitalization (not study related) (1.4%).

The serious adverse event figures are listed by group. The MBSR group had 1 serious adverse event among 75 participants at risk, and the CBT-CP group had 1 among 71 participants at risk. The usual-care group had 0 serious adverse events among 71 participants at risk. The listed number of deaths was 0 in each group. These are descriptive counts from the registry record, not estimates of comparative safety effects.

The record identifies hospitalization (not study related) as the serious-event term, with a listed percentage of 1.4%. It does not give additional serious-event terms. For other adverse events, the record lists 0 affected participants in each group, with the corresponding at-risk counts shown in the group entries. The event counts should be read alongside the stated denominators; they are not a substitute for a formal comparison or an assessment of uncertainty.

The record does not report event timing, duration, recurrence, or detailed adjudication procedures. The phrase “not study related” is part of the listed hospitalization term, but further information about how relatedness was assessed is not reported in the registry record. These safety summaries should not be taken to establish that an intervention caused or prevented an event, or that the groups had equivalent safety profiles.

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

The registry record establishes that a randomized, parallel-group trial evaluated MBSR, CBT-CP, and usual care for Veterans with chronic pain, with pain interference designated as the primary outcome. It also describes the intervention format, the outcome scale, its direction, and the planned follow-up schedule. These details help readers understand what the trial set out to assess.

The registry record does not report the primary outcome means or the results of a comparison among groups. It therefore cannot show whether pain-interference scores changed, whether one group differed from another, how large any difference was, or how precisely a difference was estimated. The scale ranges from 0 to 10, with higher scores indicating greater interference, but the scale description alone is not an outcome finding.

The record’s statement that some participants did not complete follow-up assessments also limits interpretation of the complete-data means described in the outcome entry. The intended main analyses are characterized as intent-to-treat, but those analyses and their missing-data methods are not reported in the registry record. A reader cannot infer their results from the statement that they were intended for publication.

The serious adverse event counts document what the registry lists for the groups, including one event in each of MBSR and CBT-CP and none in usual care. They do not establish that an intervention caused an event, prevented an event, or differed from another group in safety. Small or sparse event counts are especially difficult to interpret without a comparative analysis and uncertainty estimates.

In short, the record supports description of the study design and the registered outcome and safety entries, but not a conclusion about comparative effectiveness or a precise estimate of benefit or harm. Such conclusions would require outcome analyses and fuller reporting that are not reported in the registry record. The study’s completed status should not be confused with a result, and the rationale for conducting the trial should not be mistaken for evidence about what the trial found.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of why a clear outcome definition and a complete results record are both necessary. The registered primary measure is specific: a 7-item pain-interference subscale with a stated score range and direction. The schedule includes baseline, immediate post-treatment, and 6-month follow-up. These features identify what was intended to be measured and when, but they do not reveal the observed group patterns.

The three-group design also makes the choice of comparison important. MBSR, CBT-CP, and usual care create several possible contrasts, and repeated assessment times add further possible comparisons. Without a reported primary contrast and analysis, readers cannot know which statistical question the investigators used to summarize the study’s main result. This is not merely a technical detail: different contrasts can support different interpretations.

Missing follow-up data matter because the registry distinguishes complete-data means from intended intent-to-treat analyses. That distinction makes transparent reporting of both the analysis population and the missing-data method especially important. The registry record does not provide enough information to evaluate those methods or their impact on interpretation.

Finally, the safety entry illustrates the limits of sparse descriptive event counts. Group-specific counts are useful for documenting recorded events, but without a comparative analysis and uncertainty estimates they do not establish differences between groups. Taken together, the record shows why design, outcome measurement, missing-data handling, multiplicity, and reporting precision all contribute to the interpretation of a clinical trial. In this case, the design and outcome definitions are described, while comparative outcome results are not reported in the registry record.

14. 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 most important trial-specific limitation for interpreting the registry entry is the absence of reported primary outcome values and group comparisons. Although the record specifies the outcome, its score range, direction, and assessment times, it does not give means, standard deviations, estimates of between-group effects, confidence intervals, or p values. This prevents assessment of the observed direction, magnitude, and precision of the outcome.

The registry says that some participants did not complete post-treatment and 6-month assessments. It says the listed means reflect complete data, while the main analyses intended for publication are intent-to-treat. The number and pattern of missing assessments, the handling of missing data in the intended analyses, and the analyses’ results are not reported in the registry record. This leaves uncertainty about how representative the complete-data summaries are of the randomized groups.

The outcome schedule and three groups allow multiple possible comparisons, but the registry entry does not identify a single primary contrast or describe a multiplicity strategy. It also does not report the statistical model, any prespecified analysis plan, or interim analysis details. The registry description of CBT-CP and usual care is incomplete, limiting detail about treatment content. Further information on adherence, attrition by group, and implementation is not reported in the registry record.

The safety counts are descriptive and sparse, and no comparative safety analysis is reported. The record also does not supply detailed information about event timing or adjudication. These limitations concern what can be assessed from the registry record; they do not establish that additional information is unavailable elsewhere.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: An Evaluation of MBSR and CBT for Veterans With Chronic Pain — NCT04486066.
• Registry record last updated 2025-06-25; status last verified 2025-06.
• Results first posted 2025-06-25.
• 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.

18. Record Summary

NCT04486066 is a completed, randomized, unmasked, parallel-group trial sponsored by the VA Office of Research and Development. It enrolled 217 participants and evaluated MBSR, CBT-CP, and usual care for Veterans with chronic pain. The primary outcome is the Brief Pain Inventory Short Form Interference subscale, measured at baseline, immediately after treatment, and 6 months after completing treatment.

The registry describes the outcome measure and notes incomplete follow-up, with posted means reflecting complete data and intent-to-treat analyses intended for publication. However, primary outcome values and comparative analyses are not reported in the registry record. Safety entries list one serious adverse event in each of the MBSR and CBT-CP groups, none in usual care, and no deaths in any listed group. These are descriptive counts, not comparative estimates.