Mindfulness and Mechanisms of Pain Processing in Adults With Migraines: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Mindfulness and Mechanisms of Pain Processing in Adults With Migraines (NCT02695498), a randomized na study. The primary outcome is Change in Frequency of Migraine Days Per Month From Baseline.

2. Clinical Question

The clinical question concerns change over time within each randomized group, while the practical comparison of interest is whether change differed between the groups. A migraine day was defined using headache duration and intensity, or use of abortive medication, and was tracked with headache logs. This operational definition makes the endpoint more specific than a general report of headache occurrence. The registry record reports a mean change and a 95% confidence interval for each group. It does not report an estimable direct comparison between groups for this continuous endpoint, so the group-specific changes should not be treated as evidence that one course produced a larger change than the other.

3. Trial Design

The registry record describes a completed, randomized, quadruple-masked, parallel-group trial sponsored by Wake Forest University Health Sciences. Enrollment was 89. The record lists the trial start as 2016-08-26 and primary completion as 2019-07-17. The phase is listed as NA. These details identify the registered design and timeline, but do not establish how masking was implemented or maintained in practice.

Participants were assigned to Mindfulness Based Stress Reduction or Migraine/Stress Education. MBSR was described as a standardized course in mindfulness meditation and yoga. The education course addressed migraine pathophysiology, headache triggers, stress, gentle stretches, and daily migraine readings. The registry record does not report the number or length of sessions, attendance, adherence, instructor qualifications, or whether participants received other care during the trial.

The primary endpoint was change in frequency of migraine days per month from baseline to immediately after the intervention at 12 weeks. The registry reports results for 45 participants in the MBSR group and 44 in the education group. Those arm counts correspond to the reported enrollment, although participant flow, exclusions, and the number included in the endpoint analysis are not described separately. The record also lists multiple secondary outcomes relating to migraine and headache frequency, duration, severity, unpleasantness, and response to experimental heat pain. Detailed allocation procedures, the rationale for the chosen sample size, the analysis populations, and the statistical analysis plan 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

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 Frequency of Migraine Days Per Month From Baseline, measured over Baseline and immediately post-intervention (12 weeks).

The primary endpoint is change in the frequency of migraine days per month from baseline to immediately after the intervention, at 12 weeks. A migraine day was defined as a calendar day from 00:00 to 23:59 on which the participant reported at least 4 or more continuous hours of a moderate to severe headache, rated 6-10 on a 0-10 pain intensity scale, and/or treated a headache with abortive medication. Headache logs were used to track the outcome.

This definition combines duration, reported pain intensity, and treatment use. It is intended to count days meeting the trial’s specified migraine-day criteria rather than all headache experiences. Counting days over a month gives a frequency measure that can be compared between baseline and the post-intervention assessment. The endpoint is reported as a mean change, with a 95% confidence interval, for each group.

Negative changes indicate fewer migraine days at the follow-up assessment than at baseline, given the stated change-from-baseline endpoint. The posted group estimates therefore describe average within-group change. They do not, on their own, quantify the difference in change between groups. The registry record does not report additional details about how headache logs were completed, checked, or handled when observations were missing.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: it is a count of migraine days expressed as a change from baseline, and the registry reports a mean. A mean summarizes the average change across participants in a group. It can be informative about the group’s overall direction of change, but it does not show how changes varied among individual participants or how many participants had increases, decreases, or no change.

What a confidence interval conveys

A confidence interval gives a range of values compatible with the data and the method used to estimate the mean, under the assumptions of that method. In general, it is a way to communicate precision: a narrower interval indicates greater precision than a wider interval, all else being equal. It is not a range containing every participant’s change, nor does it mean that a particular proportion of participants experienced changes within its endpoints. The registry labels the reported intervals as 95% confidence intervals. The exact estimation procedure and any adjustments used to obtain them are not reported in the registry record.

The interval for each group is centered on its reported group estimate, but the group intervals do not directly answer the randomized comparison. A trial comparison typically focuses on a contrast in outcomes between assigned groups. For a change endpoint, that could be a difference in mean changes, if that is the specified estimand and the required data are available. The registry entries do not include such a contrast. They state that values were missing or not estimable for a two-arm comparison of this continuous endpoint. Consequently, an uncertainty interval for the comparative effect and a corresponding significance test are not available in the registry record.

Why the comparison matters

Within-group change and between-group difference answer different questions. A group’s baseline-to-follow-up change describes what happened over time among participants assigned to that group. A between-group contrast asks whether the changes differed across randomized groups. Change within either group can reflect more than the intervention itself, including the passage of time, measurement variation, or other influences. Random allocation is intended to support a fair comparison, but the posted within-group estimates alone do not show the effect of assignment relative to the comparator.

Randomization, masking, and a parallel-group structure are listed in the record. These design features describe the registered trial, not proof that all potential sources of bias were eliminated. The registry record does not describe sequence generation, concealment of allocation, who was masked, or how masking was assessed. It also does not give enough information to determine whether the analysis accounted for baseline values, repeated observations, or other covariates. Those details should not be inferred from the design labels.

Over-dispersion and count outcomes

As a general statistical consideration, count outcomes can vary more widely than a simple model assumes. Over-dispersion means that the observed variability exceeds what a particular count model expects. If over-dispersion is present, an analysis that ignores it may understate uncertainty. This is a general issue for count data, not a finding about this trial. The registry record does not report the distribution of migraine-day changes, a dispersion estimate, or the model used to analyze the endpoint. The posted mean and confidence intervals do not establish whether over-dispersion was assessed.

Planning illustrations

The registry’s planning illustrations are described as calculations based on the observed effect, rather than the trial’s own design. Their stated assumptions include a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation; the effect to detect is a stated fraction of the observed effect. Such calculations illustrate sample sizes under chosen assumptions. They are not evidence that the trial was designed using those assumptions, and they are not observed power. The registry record does not report the trial’s own sample-size justification or the planning inputs used when the trial was designed.

In general, power is a design-stage probability tied to a specified effect, variability, significance level, and analysis. It does not measure the probability that a result is true after data have been collected. A retrospective power calculation based on an observed estimate would not resolve the missing direct comparison or replace its confidence interval. Since the planning illustration outputs are not reported in the registry record for this record, no participant requirement from those illustrations can be stated.

The record lists no analyses. It does not report the model, estimation method, treatment of missing observations, or the population included in the primary analysis. These omissions limit reproducibility: readers cannot determine from the registry alone how the posted group estimates were calculated or whether the analysis followed a prespecified plan. The estimates can still be described as posted, but their full statistical provenance is not available in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 40 outcome measures, including 39 posted secondary outcomes. These outcomes cover several aspects of migraine and headache frequency, duration, severity, unpleasantness, and response to experimental heat pain. Considering multiple outcomes raises a general multiplicity issue: the more effects examined, the greater the chance that at least one result may appear notable by chance if each is assessed separately. This is a general statistical concern, not evidence that a particular error occurred in this trial.

The registry record does not report a hierarchy of outcomes beyond identifying a primary outcome and listing secondary outcomes. It does not report whether multiplicity adjustments were planned or applied, how time points were prioritized across outcomes, or whether any secondary analyses were prespecified. Numerical estimates for the secondary outcomes are not reported in the registry record for this record, so their direction, precision, and relationship to the primary endpoint cannot be assessed.

Missing-data procedures are also not reported in the registry record. The reported arm counts are 45 and 44, but the record does not separately state how many participants contributed data at each assessment, whether observations were incomplete, or how any missing headache-log entries were handled. It does not describe imputation, exclusions, sensitivity analyses, or reasons for missingness. These details matter because estimates can depend on which observations are available and on assumptions used to address missing values.

The analysis populations are not reported in the registry record. It is therefore not possible to establish whether the posted results used all randomized participants, only participants with observed outcomes, or another defined group. The record lists no analyses, and the analysis plan is not reported. These limitations prevent a full assessment of multiplicity control, missing-data assumptions, and consistency between the intended and reported analyses.

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 non-serious adverse event terms

The registry reports serious adverse event counts for each group. In the MBSR group, 45 participants were at risk for serious adverse events and 0 were reported as affected. In the Migraine/Stress Education group, 44 participants were at risk and 0 were reported as affected. No deaths were reported in either group. The registry lists no serious adverse event terms.

For other adverse events, the MBSR group had 1 participant affected among 45 at risk, while the education group had 0 affected among 44 at risk. These counts describe what was recorded in the registry; they do not provide event-level details, timing, severity, or an assessment of whether an event was related to an intervention. The record does not report additional context about how adverse events were collected or classified.

Zero reported serious adverse events should be read as a count in this trial record, not as proof that serious events cannot occur. Small or limited event counts provide little information about uncommon outcomes, and the registry does not provide a comparative safety analysis. These figures are descriptive and should not be used to infer a broader safety profile.

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

The posted results show negative mean changes in monthly migraine-day frequency in both randomized groups between baseline and the immediate post-intervention assessment. The MBSR estimate was -1.6, with a 95% confidence interval from -2.5 to -0.7; the education estimate was -2.0, with a 95% confidence interval from -2.9 to -1.1. The estimates describe average within-group change, with uncertainty represented by the respective intervals.

They do not establish that MBSR produced a greater reduction than migraine/stress education, or the reverse. The direct two-group comparison for this continuous endpoint is reported as missing or not estimable. Without a comparative estimate and its uncertainty, the relative effect of assignment to the two courses cannot be quantified from the registry record. The within-group confidence intervals should not be substituted for that missing contrast.

The results also do not establish how long any change lasted beyond the 12-week post-intervention assessment. They do not answer whether headache duration, intensity, unpleasantness, or experimental pain responses changed, because numerical results for the listed secondary outcomes are not reported in the registry record for this record. The registry does not report a threshold for judging whether the observed average changes would be clinically important.

General interpretation of trial results also depends on enrollment, follow-up, outcome measurement, and analysis choices. Here, details of eligibility criteria, participant flow, missing-data handling, analysis populations, and the statistical analysis plan are not reported in the registry record. That absence does not negate the posted summaries, but it limits how fully their precision and possible sources of bias can be evaluated.

The appropriate conclusion is narrow: the record reports average decreases from baseline in both groups at the stated assessment, with group-specific confidence intervals. It does not provide the direct comparative result needed to determine whether the changes differed between the courses. No claim about treatment effectiveness or an individual participant’s likely experience follows from these summaries alone.

13. Why This Trial Matters Statistically

This trial is statistically informative because it illustrates the distinction between describing change in each randomized group and estimating a difference between groups. A randomized design is organized around comparison, but the registry record’s primary results are group-specific mean changes. Because the direct continuous-outcome comparison is missing or not estimable, the most important comparative quantity is unavailable. The two arm summaries cannot be turned into a reported treatment contrast without additional information and analysis.

The endpoint also illustrates how a clinical event must be operationally defined before it can be counted. Here, a migraine day was specified using a full calendar day, a threshold for headache duration and intensity, and/or use of abortive medication. The definition supports consistent outcome tracking in principle, while leaving practical questions about headache-log completion and missing entries unanswered in the registry record.

Precision is another central issue. Each group mean is accompanied by a 95% confidence interval, allowing readers to see uncertainty around its estimate. Yet interval precision for each group does not substitute for precision around the between-group effect. This makes clear why statistical interpretation should focus on the estimand that addresses the clinical comparison, not only on whether each group’s own change interval includes zero.

The record also lists many secondary outcomes, but does not report their numerical results in the registry record for this record. This highlights why outcome multiplicity and transparent reporting matter: readers need to know which outcomes were prespecified, how analyses were handled, and whether all relevant results are available. The trial’s posted information offers a useful description of its design and primary group summaries, while the missing comparative and analytic details constrain the statistical conclusions.

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.

Several trial-specific limitations arise from details not reported in the registry record. The adult migraine population is identified, but the detailed eligibility criteria, recruitment setting, participant characteristics, and baseline distribution of migraine days are not described. Without these details, readers cannot assess how closely the enrolled sample reflects a particular clinical population or how comparable the groups were at baseline.

The record reports enrollment and arm counts but does not provide a participant-flow account. It does not state how many participants completed the intervention, posted headache logs at each assessment, or were included in the primary outcome analysis. Attendance, adherence, deviations from the courses, and use of other care are also not reported. These omissions make it difficult to understand exposure to the assigned interventions and the completeness of outcome follow-up.

The primary outcome is defined and its assessment time is identified, but the registry does not explain how headache logs were reviewed, how incomplete days were treated, or how missing observations were handled. The analysis populations, statistical model, and method used to calculate the confidence intervals are not reported. The direct between-group comparison is missing or not estimable, leaving the central comparative question unanswered by the posted primary summaries.

Finally, the registry does not report the sample-size justification, a detailed statistical analysis plan, multiplicity procedures, or numerical results for the listed secondary outcomes in the registry record for this record. The description of quadruple masking does not explain who was masked or how masking was maintained. These are reporting limitations; the registry record alone does not establish whether the details were absent from the full trial conduct or documentation.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Mindfulness and Mechanisms of Pain Processing in Adults With Migraines — NCT02695498.
• Registry record last updated 2023-11-27; status last verified 2019-08.
• Results first posted 2023-11-27.
• 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

NCT02695498 is a completed randomized, quadruple-masked, parallel-group trial sponsored by Wake Forest University Health Sciences, with enrollment of 89. It compared Mindfulness Based Stress Reduction, a standardized course in mindfulness meditation and yoga, with a migraine/stress education course.

The primary endpoint was change in monthly migraine days from baseline to immediately after the intervention at 12 weeks. The registry reports mean changes of -1.6 (95% confidence interval -2.5 to -0.7) for MBSR and -2.0 (95% confidence interval -2.9 to -1.1) for education. A direct comparison for the continuous endpoint is reported as missing or not estimable. Thus, the posted results describe group-specific changes but do not quantify the difference between groups.

Detailed analysis methods, missing-data handling, analysis populations, and numerical secondary-outcome results are not reported in the registry record.