Real-Time fMRI Feedback Effects on Pain Perception: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Real-Time fMRI Feedback Effects on Pain Perception (NCT01588197), a randomized na study. The primary outcome is Average Unpleasantness.

2. Clinical Question

The study asks whether real-time functional magnetic resonance imaging feedback may have a role as a future approach to chronic pain. The registry names cognitive pain control as the condition and lists behavioral strategies involving attention or distraction, stimulus quality or severity, and a control strategy. The arm descriptions refer to ACC Real Time fMRI Feedback and PFC Real Time fMRI Feedback, but their descriptions are truncated, so the precise activities in each arm cannot be established from the registry record.

Pain unpleasantness is distinct from a pain threshold: the stated outcome is a participant rating of how unpleasant pain feels, not simply the temperature at which pain is detected. The record specifies thermal pain threshold assessments as part of the procedure, but the primary outcome is the unpleasantness rating. The study summary frames the broader motivation as determining whether real-time fMRI might be a viable treatment for chronic pain in the future. That stated aim is not itself evidence that participants had chronic pain, nor does it establish that the study tested treatment effectiveness in a chronic-pain population.

3. Trial Design

The registry describes a randomized, parallel-group study with no masking. Its status is completed, and its enrollment is 20. The recorded phase is NA. The sponsor is the Medical University of South Carolina. The study start is listed as 2010-11, and primary completion as 2016-12.

Random allocation means that assignment was intended to occur by chance, while a parallel design means the groups are intended to receive their assigned approaches rather than crossing over between approaches. Those are general descriptions of the design labels; details about the randomization sequence, allocation concealment, and implementation are not reported in the registry record. With no masking recorded, the registry does not indicate that participants or study personnel were kept unaware of assignments. Further details about who knew assignments and when are not reported in the registry record.

The intervention list names three behavioral approaches: Attention/Distraction Strategy, Stimulus Quality/Severity Strategy, and Control Strategy. The arm descriptions begin with thermal pain threshold assessments using an MRI-compatible thermode and refer to cognitive pain instructions, but the descriptions are truncated. The arm titles identify ACC Real Time fMRI Feedback and PFC Real Time fMRI Feedback. Separately, the adverse-event information uses the group labels Real Time fMRI Feedback and No Feedback. The registry record does not explain how these different labels correspond, or how the three named interventions were assigned to the listed arms. It is therefore not possible to give a more specific account of the comparison without guessing.

The stated measurement schedule includes ratings before the fMRI paradigm at baseline and directly after it, within a timeframe described as before and after the paradigm, an average of 2 hours. Whether measurements were repeated at other times, and how the multiple outcome categories or time points were intended to be analyzed, is not reported in the registry record. The record lists no analyses. The reason for the enrollment target, details of trial conduct, and any changes to the design 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

Reasons for not completing this period:

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 participants did not complete MRI scanning and so were not included in analyses

6. Primary Endpoint

The registry lists the primary outcome as Average Unpleasantness, measured over Before and After fMRI Paradigm, an average of 2 hours.

The primary outcome is Average Unpleasantness, measured in units on a scale. The registry describes the summary measure as a mean with standard deviation and gives a rating scale from 0 to 10. The endpoints are described at baseline, before the fMRI paradigm, and directly after the paradigm. A rating of 0 means no unpleasantness; a rating of 10 means the worst unpleasantness imaginable. The timeframe is stated as before and after the fMRI paradigm, an average of 2 hours.

A mean gives a measure of the central level of the ratings, while a standard deviation describes how spread out individual ratings are around that mean. In general, a patient-reported rating can capture an experience that is not fully represented by a threshold measurement alone. Pain threshold assessments are part of the described procedure, but unpleasantness is the named primary outcome; they should not be treated as interchangeable measurements.

Comparing ratings before and after a paradigm can describe change over the measurement period. However, the registry record does not report the means, standard deviations, participant-level changes, or an analysis comparing the groups. It also does not reduce the outcome to one comparison, as the record notes several categories or time points. Consequently, the endpoint definition clarifies what was intended to be measured, but the posted registry information does not establish the observed pattern of ratings or its precision.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies a continuous primary outcome summarized by a mean and standard deviation. These are descriptive statistics: the mean represents the average rating, and the standard deviation describes variation among ratings. They do not, on their own, quantify a between-group effect or indicate how precisely that effect is estimated. The registry record does not report the outcome summaries or an inferential analysis.

What does a comparison estimate?

In general, an intervention comparison estimates how outcomes differ under the assigned approaches. The choice of comparison must be explicit. For measurements taken before and after an intervention, investigators might analyze the post-intervention values, changes from baseline, or a model that accounts for baseline values. These approaches can answer related but not identical questions. The registry record does not report which method was planned or used for Average Unpleasantness, and it does not identify a single primary comparison across the recorded categories or time points.

For a repeated measurement, observations from the same participant are related rather than independent. A suitable analysis generally accounts for that within-participant relationship. If comparing groups, the analysis also needs to reflect the randomized assignment and the outcome’s timing. These are general considerations, not claims about the method used in this study. The registry lists no analyses, so its statistical model, handling of repeated ratings, covariates, and analysis population are not reported in the registry record.

What do uncertainty measures add?

A point estimate describes the observed effect on a chosen scale, while a confidence interval conveys uncertainty around that estimate under the model’s assumptions. A p-value, when reported, addresses how compatible the observed data are with a specified null hypothesis under those assumptions; it does not measure clinical importance or the probability that a hypothesis is true. Neither a point estimate, confidence interval, nor p-value for the primary outcome is reported in the registry record. Without them, statistical significance and precision cannot be evaluated.

Standard deviations and standard errors have different roles. A standard deviation describes the spread of individual observations; a standard error describes uncertainty in an estimated quantity. The endpoint lists standard deviation as its dispersion measure, but no values are posted in the registry record. It would be inappropriate to treat a standard deviation as a confidence interval or infer an effect’s precision from the endpoint definition alone.

Why can over-dispersion matter?

In general, over-dispersion occurs when observed variability exceeds what a statistical model assumes. If ignored, standard errors may be too small and confidence intervals may be too narrow. The concept is especially relevant to certain count or categorical models; it cannot be assumed to apply to this continuous rating outcome. The registry record does not report a model or a diagnostic assessment, so there is no basis for saying that over-dispersion was present or addressed in this study.

The planning illustration described in the registry is a calculation from an observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. It varies the target effect as a fraction of the observed effect and reports participants per arm for non-time-to-event outcomes. Such calculations illustrate how a hypothetical future study’s required size depends on assumptions about effect and variability. They are not observed power, do not prove that the completed study was adequately powered, and are not the trial’s original design justification. The sample-size justification and the statistical plan are not reported in the registry record.

How should multiple outcomes or time points be handled?

When several outcomes, categories, time points, or comparisons are examined, the chance of a false-positive finding can increase if each is tested without adjustment. In general, multiplicity methods may control this risk or designate a primary comparison in advance. The record indicates that the primary outcome includes several categories or time points and was not reduced to one comparison. It does not report a multiplicity strategy, a hierarchy of comparisons, or inferential analyses. No conclusion about adjustment can therefore be made.

For interpretation, the most informative reporting would identify the estimand or contrast, analysis population, model, effect estimate, interval estimate, and handling of missing observations. Those details are not reported in the registry record. The available endpoint description and design labels establish context, but they do not substitute for outcome data or a statistical analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry identifies Average Unpleasantness as the primary outcome, but notes that it has several categories or time points and is not reduced to one comparison. It lists no analyses. The specific primary contrast, any secondary comparisons, and any plan for controlling multiplicity are not reported in the registry record. In general, testing multiple outcomes or time points without an appropriate strategy can increase the chance of a false-positive result. The record does not support a judgment about whether this risk was addressed.

Missing-data handling is also not reported in the registry record. There is no description of how incomplete ratings, missed assessments, or withdrawals were treated; whether any imputation was used; or whether sensitivity analyses were conducted. The analysis population is not reported either. It is not possible to determine whether the intended analysis included all randomized participants, only participants with observed measurements, or another population.

These omissions matter because missingness and analysis choices can affect both the estimate and its uncertainty. General methods include examining reasons for missingness and comparing plausible assumptions, but no such procedures can be attributed to this study. The registry record also does not report a statistical analysis plan, interim analyses, or a sample-size justification. Without these details and the outcome results, the credibility and robustness of any treatment comparison cannot be assessed from the registry information.

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.

The safety information lists two groups: Real Time fMRI Feedback and No Feedback. For each group, the registry records 9 participants at risk for serious adverse events and 0 serious adverse events; it also records 9 at risk for other adverse events and 0 other adverse events. Deaths are listed as 0 in each group. No serious adverse-event terms are listed.

These figures describe what the registry records, not a complete account of how safety was monitored or what events were actively sought. The registry does not report the event definitions, observation period for safety, ascertainment procedures, or whether the listed at-risk counts represent everyone enrolled or a safety population. The figures should therefore be read as no events recorded in the displayed categories for the listed groups, rather than as proof that no adverse events could occur.

The enrollment is listed as 20, while the safety information gives 9 at risk in each of its two named groups. Those entries should not be combined or reconciled by inference; the registry does not explain the difference in the recorded counts. Zero recorded events also does not establish equivalence between groups, particularly without a reported comparative analysis or uncertainty estimate. The record does not report a safety analysis beyond the counts.

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

The registry record establishes that a randomized, parallel-group study of real-time fMRI feedback and pain perception was completed and that Average Unpleasantness was the named primary outcome. It specifies a 0-to-10 rating scale and measurements before and directly after the MRI paradigm. It also records safety counts for feedback and no-feedback groups. These registry entries describe the study’s structure and measurement, not the effect of the intervention.

The primary outcome result is not reported in the registry record. The record lists no analyses and notes that the outcome spans several categories or time points without a single comparison. No effect estimate or uncertainty measure is reported. Consequently, the available registry information does not establish whether unpleasantness changed, whether any change differed between groups, or how precise a comparison might be. It cannot support a conclusion that feedback improved or failed to improve pain perception.

The study summary frames the purpose as assessing whether real-time fMRI may be a viable treatment for chronic pain in the future. That purpose should not be mistaken for a demonstrated treatment effect. Chronic-pain status of participants, longer-term outcomes, and follow-up beyond the stated before-and-after timeframe are not reported in the registry record. The primary endpoint is a rating of unpleasantness around an MRI paradigm, not by itself evidence about durable effects or broad clinical benefit.

The safety listing records zero serious events, zero other events, and zero deaths in each named group. This is a limited registry account, and details about safety ascertainment and the relationship between listed counts and enrollment are not reported. It should not be interpreted as proof of no risk.

Overall, the record supports a description of the research question, design labels, endpoint, and selected safety entries. It does not provide enough outcome or analysis information to estimate an effect or judge its precision. Any broader interpretation would go beyond what the registry record reports.

13. Why This Trial Matters Statistically

This study raises a statistical question that is common in early investigations of behavioral and imaging-based approaches: how should a short-term, subjective outcome be compared across randomized groups and measurement times? The registry defines unpleasantness ratings before and after an MRI paradigm, but the outcome spans multiple categories or time points and is not reduced to one comparison. That makes the choice of estimand and analysis central to interpretation.

The design labels matter, but they are only a starting point. Randomization is intended to make groups comparable on average, yet a randomized label cannot substitute for a clearly reported contrast, estimate, and uncertainty interval. A parallel design and no masking are also relevant context, while the registry does not report the sequence-generation or masking details needed to assess implementation. Statistical interpretation depends on transparent reporting of those choices alongside the results.

The outcome’s scale also highlights the distinction between a measured rating and a clinical claim. A mean and standard deviation can describe ratings, but an intervention question needs a comparative estimate and an assessment of its precision. The record does not report those results. This is why a clearly defined endpoint, complete follow-up information, and an explicit analysis population are important even in a small, focused study.

Finally, the record demonstrates why planning illustrations must be separated from study findings. A sample-size calculation based on an observed effect and stated assumptions can inform planning for later research, but it is not observed power and does not remedy missing outcome reporting. Without the primary result and its uncertainty, statistical significance, practical importance, and reproducibility cannot be evaluated. The trial’s topic is relevant to pain research, but the registry information leaves the central statistical comparison unresolved.

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 principal limitation for interpreting the trial is that the registry record does not report the primary outcome results or any analyses. It therefore gives no estimate of Average Unpleasantness, no confidence interval, and no statistical test. The record also notes that the primary outcome covers several categories or time points without a single comparison, leaving the intended contrast unclear.

Descriptions of the intervention and arms are incomplete or use differing labels. The intervention list names three behavioral strategies, the arm descriptions identify ACC and PFC real-time fMRI feedback, and the adverse-event information labels groups Real Time fMRI Feedback and No Feedback. The registry does not clarify how these descriptions correspond. The arm descriptions themselves are truncated, limiting what can be said about the assigned procedures.

The registry record does not report whether participants had chronic pain, although chronic pain appears in the study’s stated future-treatment motivation. This limits the ability to characterize the population or connect the stated motivation to the participants studied. It also does not report allocation procedures beyond the randomized label, the statistical plan, a sample-size justification, missing-data handling, or the analysis population.

The endpoint is measured before and directly after the MRI paradigm, with a timeframe described as an average of 2 hours. Longer-term outcomes and follow-up are not reported in the registry record. The safety counts are limited to the listed categories, and safety ascertainment details are not reported. In addition, the safety counts do not match the enrollment figure in a way the record explains. These gaps prevent a full assessment of outcome completeness, precision, safety, and generalizability.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Real-Time fMRI Feedback Effects on Pain Perception — NCT01588197.
• Registry record last updated 2019-06-14; status last verified 2019-03.
• Results first posted 2019-06-14.
• 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

The registry record identifies a completed randomized, parallel-group study with no masking, sponsored by the Medical University of South Carolina. Enrollment is listed as 20. The study began in 2010-11, with primary completion in 2016-12. Its stated motivation is to determine whether real-time fMRI may be a viable future treatment for chronic pain.

The primary outcome is Average Unpleasantness, a mean rating on a 0-to-10 scale, measured before and directly after the fMRI paradigm. Behavioral strategies and real-time fMRI feedback appear in the intervention and arm descriptions, but their mapping is not clear because the descriptions are truncated or use different labels. The registry lists no analyses and does not report primary outcome results. Safety entries record zero serious adverse events, zero other adverse events, and zero deaths for each named group. The statistical plan, sample-size justification, missing-data methods, and analysis population are not reported in the registry record.