Transcranial Magnetic Stimulation for Facial Pain: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Transcranial Magnetic Stimulation for Facial Pain (NCT02633306), a na na study. The primary outcome is Visual Analogue Scale (VAS).

2. Clinical Question

3. Trial Design

This was a completed, single-group study of transcranial magnetic stimulation for complex oro-facial pain. The registry lists enrollment as 9. It gives allocation as NA and masking as none; there was no separate randomized control group. The sponsor was the University of Minnesota. The recorded study start was 2016-08-01, and primary completion was 2019-07-01.

The study had several aims: to characterize baseline MRI patterns in patients with chronic oro-facial pain without a definitive etiologic diagnosis, to estimate the rate of treatment success with stimulation of the primary motor cortex, and to identify post-treatment MRI patterns associated with treatment success. These aims span clinical measurement and imaging characterization. The primary outcome listed in the registry, however, was pain on a visual analogue scale, assessed as a mean difference from baseline to 7 days after treatment.

The registry describes three patients leaving before treatment. Of the 6 who began treatment, one did not complete the full treatment regimen, and post-treatment status could not be assessed for that participant. These details matter when interpreting the outcome: the baseline-to-post-treatment assessment was not available for every person who began treatment.

The listed intervention was transcranial magnetic stimulation, recorded as a device. The registry record does not report detailed treatment settings, the procedures used to deliver treatment, or the protocol for MRI acquisition and interpretation. Phase is listed as NA. The registry record also does not report a statistical analysis plan, a sample-size justification, or the allocation procedures beyond NA. The study's single-group structure means that its before-and-after measurements do not provide a like-for-like comparison with an untreated or alternative-treatment group.

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: Three patients left the study before treatment. One of 6 patients who began treatment did not complete the full treatment regimen and therefore post treatment status could not be assessed.

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.

Population: 2 of the 9 participants withdrew participant prior to the collection of baseline data. All 7 participants from whom data was collected are reported here.

6. Primary Endpoint

The registry lists the primary outcome as Visual Analogue Scale (VAS), measured over 7 days.

The primary endpoint was the Visual Analogue Scale (VAS), a pain score measured on a scale from 0, representing no pain, to 100, representing the worst possible pain. The registry describes the endpoint as the mean difference between baseline and 7 days after treatment. It also identifies the measure as continuous and specifies the mean and standard deviation as the summary statistics.

A continuous pain scale can retain information about the degree of reported pain rather than reducing responses to broad categories. A mean difference can describe the average change between the two assessment times. The standard deviation describes how spread out individual scores are around their mean; it is not the same as uncertainty about the mean difference. Because each assessment is intended to relate to the same participant over time, the measurements are naturally understood as repeated observations, although the registry record does not report the statistical method used to analyze them.

The endpoint gives a defined time for the post-treatment assessment: 7 days. The registry record does not report the observed mean difference, the standard deviation, or an interval estimate for this outcome. It therefore does not permit a numerical description of the amount or precision of the recorded change. The scale's direction is clear for individual pain scores, but no numerical change estimate is reported from which to characterize the direction of the study's average result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies a continuous primary outcome and specifies the mean and standard deviation as summary statistics. Understanding those summaries helps separate the size of an observed change from the variability of individual measurements and the uncertainty around an estimated average.

What does a mean difference represent?

In general, a mean is the arithmetic average of observed scores. A mean difference compares averages at two measurement times. For a repeated measure such as pain at baseline and after treatment, that difference can be calculated from within-participant changes or from a model that accounts for repeated observations. These approaches can have different assumptions and can handle incomplete records differently. The registry record does not report which approach was used, nor does it provide the numerical mean difference.

The scale endpoints give the score a plain-language interpretation: 0 means no pain, and 100 means the worst possible pain. The mean difference would indicate the average change on that scale, but the record does not report its value or specify a numeric direction for the subtraction. It would therefore be inappropriate to infer whether the average score rose or fell, or to describe the magnitude of any change.

What does the standard deviation tell the reader?

In general, a standard deviation describes how much observed scores vary around their mean. A relatively broad spread indicates more variation among measurements, while a narrower spread indicates that measurements are more clustered. It does not by itself show how precisely the average has been estimated. Precision also depends on the amount of usable information and on the analysis method. The registry identifies standard deviation as the dispersion measure but does not report its observed value for the primary endpoint.

How is uncertainty different from variability?

A confidence interval is a statistical summary of uncertainty around an estimated quantity under the assumptions of the analysis. It can show a range of values compatible with the data and model, rather than focusing only on the point estimate. The interval's width reflects precision: a wider interval indicates less precision than a narrower one. This is a general explanation; the registry record does not report a confidence interval for the primary outcome. A p-value, when used, addresses compatibility between data and a specified null model. It does not measure the size or clinical importance of an effect. No primary-outcome p-value is reported in the registry record.

Why does the single-group design matter?

In general, observing a measure before and after an intervention can describe change over time, but it cannot by itself establish what would have happened over the same period without the intervention. A concurrent comparison group can help separate treatment-related change from background change, provided the comparison is appropriately designed and analyzed. This study is listed as single group, with allocation NA and no masking. Its recorded endpoint is a baseline-to-follow-up measure, not a randomized contrast between groups. The registry record does not report a method that would address the absence of a control group.

What can be said about planning calculations?

The planning assumptions describe an illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They describe detecting a stated fraction of the observed effect. Such calculations are planning illustrations, not observed power and not results from the study. They also do not change the study's recorded single-group design: a two-arm allocation is an assumption for the illustration, not a control comparison in the trial. The numerical planning outputs and the observed primary effect are not reported in the registry record, so no planning count or recalculation can be stated from that record.

What remains unknown about the analysis?

The registry record does not report the statistical test or model, whether any covariates were included, how repeated measurements were handled, or whether confidence intervals were calculated. It does not report checks of distributional assumptions or how missing outcome information was treated. These details matter because different choices can affect the estimate and its uncertainty. Without the analysis description and numerical outcome results, the endpoint definition can be explained, but the statistical result cannot be independently interpreted or reproduced from 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("Transcranial Magnetic Stimulation")
n   <- c(5)
m   <- c(5.4)
sp  <- c(11.7)
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  Transcranial Magnetic Stimulation  5  5.400  11.700  -9.127  19.927

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 7 outcome measures and 7 analyses. It identifies the primary pain outcome and also lists World Health Organization Quality of Life Abbreviated measures for overall quality of life and physical health, psychological health, social relationships, and environment. When a study examines several outcomes or analyses, the chance of finding an apparently notable result by chance can increase. In general, multiplicity methods can account for this, but the method depends on the analysis plan and the relationship among outcomes. Whether a multiplicity adjustment was planned or applied is not reported in the registry record.

Missing information is relevant to the primary outcome. Three patients left before treatment. Of the 6 who began treatment, one did not complete the full regimen, and post-treatment status could not be assessed for that participant. The registry record does not report the reasons for leaving, a missing-data method, or the number included in each outcome analysis. It does not report whether the analysis used only participants with observed post-treatment measurements, used an imputation approach, or applied another method. These are possible general approaches, not descriptions of what this study did.

The record does not specify an analysis population, such as whether all enrolled participants or only those who started or completed treatment were included in particular analyses. It also does not report sensitivity analyses that might examine how conclusions depend on assumptions about missing outcomes. Because the primary outcome estimate itself is not reported, the impact of missingness on that estimate cannot be assessed. The registry's stated outcome and participant-flow details make the issue visible, but they do not resolve how missing data affected the analysis.

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 non-serious adverse event terms

The registry records 6 participants at risk for serious adverse events and 0 affected. It records 6 at risk for other adverse events and 6 affected. The death count is 0. These are event counts as entered in the registry, not estimates of comparative risk: the study has a single group and no control group.

The serious-event count should be read in the context of the number at risk and the study's size. A recorded count of 0 means no serious adverse event was recorded among those listed as at risk; it does not demonstrate that such events cannot occur or that the risk is absent. The registry does not provide serious adverse-event terms, and it does not identify the types of other adverse events. The term list for serious events is empty in the record.

The other-adverse-event figure indicates that all 6 participants listed as at risk were recorded as affected. The registry does not report the event descriptions, severity, timing, duration, or whether events were considered related to treatment. Those details are important for a fuller safety interpretation. The counts alone cannot establish the nature or clinical importance of the reported events, and they do not permit a comparison with another treatment or with no treatment.

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

The study's registry record establishes what the investigators set out to examine: transcranial magnetic stimulation for complex oro-facial pain, a baseline-to-7-days-after-treatment pain score, and MRI patterns that might relate to treatment success. It also documents a completed single-group study with enrollment of 9 and describes the participant follow-up gap. These registry entries clarify the scope of the investigation, but they are not themselves evidence of a measured treatment effect.

The primary outcome result is not reported in the registry record. Without the observed mean difference, its variability, or an uncertainty estimate, the amount and precision of any change in pain cannot be described. The record also does not report a definition or numerical rate of treatment success, or numerical findings for the imaging aims. Accordingly, the listed aims should not be confused with results demonstrating that those aims were achieved.

Even if a before-and-after estimate were available, the single-group design would limit causal interpretation. A change from baseline could reflect treatment, but could also reflect other influences over time or the way measurements vary. A randomized control comparison is not part of the recorded design. This is a design limitation, not a claim that any particular alternative explanation occurred.

The safety counts show 0 serious adverse events among 6 at risk, 6 affected by other adverse events among 6 at risk, and 0 deaths. The lack of reported event details limits interpretation of the latter count and the overall safety profile. These counts should not be taken as proof of absence of risk, and they do not compare safety against another group.

In short, the registry record is informative about study structure, outcome definitions, follow-up, and recorded adverse events. It does not provide enough outcome detail to quantify the primary result, assess its precision, or establish a treatment effect. No clinical recommendation follows from the information recorded.

14. Why This Trial Matters Statistically

This study is statistically informative in part because it illustrates the difference between specifying an outcome and reporting its result. The registry defines a continuous pain measure and a follow-up time, and it identifies the intended summary as a mean difference with standard deviation. Those choices make the research question understandable. Yet without the estimate and its uncertainty, a reader cannot judge the size, direction, or precision of the observed change.

The single-group design also highlights a central issue in clinical research: a before-and-after contrast answers a different question from a randomized comparison. It can describe how measurements changed among participants with observed follow-up, but it cannot by itself distinguish treatment-related change from changes that might have occurred over time for other reasons. Being explicit about this distinction prevents an uncontrolled change from being interpreted as a controlled treatment effect.

Participant flow is another important statistical feature. Three patients left before treatment, and one of 6 who started treatment did not complete the regimen, leaving post-treatment status unavailable for that participant. These details show why analysis populations and missing-data methods matter. The registry record does not explain how these issues were handled, so the reader cannot determine their effect on the endpoint analysis.

Finally, the study's aims include imaging characterization alongside clinical outcomes. Connecting imaging patterns to treatment success would require clearly reported definitions, estimates, and analysis methods. The registry record does not report those results. Taken together, the record underscores that design, endpoint definition, follow-up, and complete statistical reporting all shape what can be learned from a clinical study.

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.

Several limitations are specific to the information recorded for this study. First, its single-group design lacks a concurrent control group. The baseline-to-7-days-after-treatment pain comparison can describe change over time, but it cannot separate a treatment-associated change from other influences. Allocation is listed as NA and masking as none, so the registry does not describe randomization or masking that could support a controlled contrast.

Second, the participant flow creates incomplete post-treatment assessment. Three patients left before treatment, and one of the 6 who began treatment did not complete the full regimen, so post-treatment status could not be assessed for that participant. The registry record does not report why these participants left, whether their baseline characteristics differed from those with follow-up, or how the missing outcome was handled. The direction or magnitude of any resulting bias cannot be determined from the recorded information.

Third, the primary outcome result is not reported. The record specifies the VAS and its assessment timing but gives no numerical mean difference, standard deviation, confidence interval, or p-value. Without these, neither the observed change nor its statistical precision can be evaluated. The record also does not provide outcome results for the listed quality-of-life measures or numerical findings for the imaging aims.

Further limitations of interpretation arise because the registry does not report detailed treatment procedures, the definition of treatment success, the statistical analysis plan, or multiplicity and missing-data methods. The adverse-event record lacks descriptions of the other events and details of severity or timing. These omissions constrain interpretation of both outcomes and safety; they do not establish that unreported procedures or analyses were absent from the study.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Transcranial Magnetic Stimulation for Facial Pain — NCT02633306.
• Registry record last updated 2021-04-08; status last verified 2021-03.
• Results first posted 2021-04-08.
• 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

NCT02633306 is a completed, single-group study sponsored by the University of Minnesota. Enrollment is listed as 9; the study start was 2016-08-01, and primary completion was 2019-07-01. The intervention was transcranial magnetic stimulation, and the primary outcome was the mean difference in Visual Analogue Scale pain score from baseline to 7 days after treatment.

The registry describes three patients leaving before treatment and one of 6 who began treatment not completing the full regimen, leaving post-treatment status unavailable for that participant. It does not report the numerical primary outcome result or its uncertainty. Safety figures list 0 serious adverse events among 6 at risk, other adverse events affecting 6 of 6 at risk, and 0 deaths. The record does not give descriptions of the other adverse events.