Comparison of Therapeutic Effects of Greater Occipital Nerve Block, Topiramate, and Flunarizine on Episodic Migraine: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of Therapeutic Effects of Greater Occipital Nerve Block, Topiramate, and Flunarizine on Episodic Migraine (NCT03712917), a randomized na study. The primary outcome is Visual Analog Scale.

2. Clinical Question

3. Trial Design

The registry record describes a randomized, double-masked, parallel-group study comparing greater occipital nerve block, topiramate, and flunarizine in people with episodic migraine. The listed enrollment is 120, and the brief summary describes an estimated allocation of 40 participants to each treatment group. The study status is completed. Its recorded start date is 2019-03-01, and its primary completion date is 2019-03-31.

The planned follow-up period was four weeks. The brief summary says attack frequency and Visual Analog Scale scores were to be recorded weekly. It also describes calculating response rates based on 50% and 75% or more reductions in pain scores and attack frequencies at the end of follow-up. These are descriptions of intended assessments, not posted outcome findings.

The record lists greater occipital nerve block as a procedure and the other two interventions as drugs. It describes topiramate as starting at 25 mg/day twice a day and increasing to 100 mg/day in the second week; flunarizine is described at 10 mg/day as a single dose. The nerve-block description specifies its solution and some administration details, but the procedure description is incomplete in the registry record. Further details of randomization, masking implementation, 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

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.

6. Primary Endpoint

The registry lists the primary outcome as Visual Analog Scale, measured over Post treatment 4 weeks.

The listed primary outcome is the Visual Analog Scale score at post-treatment four weeks. The scale is described as measuring pain from 0, meaning no pain, to 10, meaning worst pain. The endpoint is recorded as a mean with standard deviation, so its intended summary is the average score and the spread of individual scores around that average.

A pain scale can translate a participant’s subjective experience into a structured measure that can be compared across treatment groups and assessment times. A change or difference in average score may describe the pattern of pain reported by participants, while the standard deviation helps convey how varied those scores are within a group. Neither statistic alone shows the full distribution of responses or whether a difference matters to participants.

The registry record does not give the observed group means, standard deviations, or a treatment contrast for this endpoint. It also does not identify a specific primary comparison among the three groups. The brief summary mentions attack frequency and response thresholds as planned assessments, but the record does not provide their outcome values either.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record gives useful information about the design and the intended outcome, but does not report an analysis plan or any completed outcome analyses. The methods below explain how common statistical quantities would be interpreted in general; they do not describe analyses confirmed to have been used in this trial.

What does randomization contribute?

In general, random allocation is used to reduce systematic differences in participant characteristics between treatment groups. This supports a causal comparison when the allocation process is implemented as intended and when outcomes are collected and analyzed appropriately. Randomization does not ensure that groups will be identical, especially in a particular study. The registry record labels the study randomized but does not report the sequence-generation method, allocation concealment, or whether allocation was stratified.

The parallel-group model means that participants are assigned to a group and the groups are compared over the study period. The record identifies three groups: greater occipital nerve block, topiramate, and flunarizine. It does not report which pairwise or overall comparisons were designated as primary, or how comparisons among all groups would be handled in the analysis.

How should a mean and standard deviation be read?

For a continuous measure such as a pain score, the mean describes the average recorded value in a group. The standard deviation describes the extent to which individual values tend to vary around that average. A mean alone cannot show whether most participants had values close to it or whether responses were widely dispersed. The standard deviation is not the uncertainty of the estimated mean; that uncertainty is commonly expressed with a standard error or confidence interval.

In general, a confidence interval gives a range of values compatible with the data and the statistical assumptions used to construct it. A narrower interval indicates greater precision than a wider interval, but the interval does not by itself determine whether an observed difference is important to participants. No confidence interval or treatment-effect estimate for the four-week Visual Analog Scale score is reported in the registry record.

What would a treatment comparison require?

Comparing group averages typically requires a defined contrast, such as a difference between two group means, together with an uncertainty estimate. For a study with three groups, an analysis could address an overall difference among the groups or particular pairwise differences. These approaches answer different questions and may require a plan for controlling the risk of false-positive findings when multiple comparisons are made. The registry record does not report which approach was planned or used.

The brief summary describes weekly measurements and outcomes at the end of the four-week period. Repeated measurements can be analyzed in several ways, and the choice affects the question being answered. For example, an analysis might focus on the final measurement, change over time, or the pattern across repeated assessments. This is a general distinction; the statistical method for the weekly scores is not reported in the registry record.

Why do assumptions matter?

Statistical methods rely on assumptions about the data and study conduct. For a mean-based comparison, relevant considerations can include the distribution of values, the independence of observations, and whether the variability is adequately represented by the chosen model. If observations are more variable than a model assumes, uncertainty may be understated unless the analysis accounts for that extra variation; this general issue is called over-dispersion in settings where it applies. The registry record does not report diagnostic checks or model assumptions for this study.

Attack frequency is a count-like outcome, whereas the Visual Analog Scale score is described as a continuous measure summarized by a mean and standard deviation. Count outcomes can have different statistical properties from continuous scores. In general, a model for counts may need to account for the relationship between the mean and variability, and for any clustering or repeated measurements. The registry record does not specify how attack frequencies were to be analyzed.

What can planning calculations say?

In general, a sample-size calculation is a planning exercise based on assumptions about the effect to detect, variability, significance level, allocation, and desired power. It is not evidence that a study had a particular probability of detecting its observed result after the fact. The record describes a planning illustration based on a fraction of an observed effect and states assumptions of a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. This illustration is not identified as the trial’s own design justification. The numerical effect and the trial’s sample-size justification are not reported in the registry record.

Because outcome estimates and analysis results are absent, no recalculated comparison can be interpreted. A recalculation from summary statistics would be an unadjusted analysis, distinct from a sponsor’s own analysis; if the two disagree, the sponsor’s own analysis takes precedence. The registry record contains no sponsor analysis results to compare with a recalculation.

10. Multiplicity, Missing Data and Analysis Populations

The trial description includes three treatment groups, a primary pain-score outcome, and planned tracking of attack frequency. The brief summary also describes response rates based on 50% and 75% or more reductions and weekly assessments. Considering multiple outcomes, thresholds, time points, and group comparisons can create multiplicity: the more questions tested, the greater the general chance of at least one apparently unusual result arising by chance. The registry record does not report a multiplicity strategy, such as a hierarchy of outcomes or an adjustment for multiple comparisons.

The record does not report a statistical analysis plan, a prespecified primary contrast, or the method used to select the time point and analysis population. The listed primary endpoint is the Visual Analog Scale score at post-treatment four weeks, but the brief summary also describes other measurements. The registry record does not explain how the role of these assessments was prioritized in analysis.

Missing data can affect estimates when measurements are unavailable, particularly if missingness is related to participants’ outcomes or treatment experiences. The registry record does not report follow-up completion, missing outcome counts, reasons for missingness, or methods for handling missing observations. It also does not report whether analyses followed an intention-to-treat principle or used another analysis population. Therefore, the extent to which outcome analyses included all randomized participants cannot be determined from the registry record.

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 adverse-event record lists zero serious adverse events among 40 participants at risk in each of the three groups. It also lists zero deaths in each group. These counts describe what is entered in the registry record; they do not establish that no events occurred outside the recorded definitions or observation period.

For other, non-serious adverse events, the record lists zero affected participants in the greater occipital nerve block group, 4 in the topiramate group, and 3 in the flunarizine group. These are counts, not a statistical comparison. The record does not provide event descriptions, severity details beyond the serious-versus-other classification, timing, duration, or a comparative analysis. It also does not report whether participants could experience more than one event.

Safety counts should be read alongside the number of participants monitored, the event definitions, the observation period, and completeness of reporting. The record supplies denominators of 40 for each group in the adverse-event listing, but does not describe the safety analysis population or collection procedures. The four-week follow-up described in the study summary gives context for the planned study period, but the safety listing does not state a separate event-collection timeframe.

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

The registry record makes the comparison clinically and statistically identifiable: it concerns episodic migraine, three specified interventions, and a four-week follow-up, with a post-treatment Visual Analog Scale score named as the primary endpoint. It also outlines planned weekly recording of pain scores and attack frequency. Those details clarify what the study intended to examine.

They do not reveal which group had a higher or lower average pain score, whether attack frequency changed, how participants responded, or how uncertain any difference might be. The record contains no reported outcome estimates or analyses. It therefore does not support a conclusion about the relative results of greater occipital nerve block, topiramate, or flunarizine.

Even when a numerical difference is available, statistical interpretation requires attention to its size and precision, the analysis method, and the study’s outcome definitions. A p-value alone would not convey the magnitude of an effect, and a confidence interval would be needed to describe uncertainty around an estimate. Neither is reported for the primary endpoint in the registry record.

The listed adverse-event counts are also limited. The serious-event and death counts are zero in each group, while non-serious affected-participant counts are recorded for the drug groups. These entries do not provide enough information to compare safety comprehensively, because event details, analysis methods, and reporting completeness are not described.

The distinction is between a completed study record and a record with interpretable results. Completion status indicates the study is marked completed, but it does not itself provide evidence about outcomes. The findings and their uncertainty are not reported in the registry record, so no conclusion about benefit or lack of benefit follows from the information recorded.

13. Why This Trial Matters Statistically

This study is statistically interesting because it places a procedure and two preventive drugs in a randomized, parallel-group comparison. Such a design can address comparative questions directly when allocation, follow-up, and analysis are adequately documented. The record identifies the treatment groups and a specific post-treatment pain measure, giving readers a starting point for understanding the intended comparison.

It also illustrates why endpoint definitions and analysis plans matter. The primary outcome is a mean pain score at four weeks, while the brief summary describes repeated weekly scores, attack frequency, and response thresholds. These measures can answer related but distinct questions. A clear prespecified hierarchy and analysis plan would help explain which result is primary and how the other assessments are interpreted. That information is not reported in the registry record.

The entry also shows the limits of design information without results. Randomization, masking, and a stated enrollment do not reveal the estimated treatment effects, their precision, or how much data were available for analysis. Readers need outcome summaries and analysis details to evaluate a comparison rather than infer results from the study’s stated aims or completion status.

Finally, safety counts require context as well as numerators and denominators. The registry record lists serious and other adverse events, but does not give event descriptions or a comparative analysis. Statistical interpretation depends on how events were defined and collected, and on whether follow-up was complete. These considerations apply generally to clinical-trial reporting and are particularly relevant when a registry entry contains design and safety information but no outcome analyses.

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 main limitation for interpretation is that the registry record does not report outcome results or analyses. It identifies the four-week Visual Analog Scale score as the primary outcome but gives no group-level values or comparison estimates. Planned attack-frequency and response-rate assessments are described without corresponding results.

Further trial details needed to assess risk of bias are not reported in the registry record. These include the randomization method, allocation concealment, how masking was implemented, and the statistical analysis plan. The record labels the study double-masked, but does not describe who was masked or how masking was maintained for the procedure and drug groups.

The brief summary estimates 40 participants per group, and enrollment is listed as 120. The record does not report the number randomized to each group in the final analysis, participant flow, withdrawals, or outcome completion. It also does not state how missing measurements were handled or define the analysis population.

The procedure description is truncated in the registry record, limiting interpretation of the full intervention protocol. Eligibility criteria, baseline characteristics, and details of concomitant care are not reported in the information recorded. The registry record also does not identify a primary comparison among the three groups or explain how the several planned outcomes, thresholds, and weekly measurements were prioritized. These omissions prevent assessment of the comparability of analyzed groups, the effects of missing data, and the interpretation of any planned multiple comparisons.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Comparison of Therapeutic Effects of Greater Occipital Nerve Block, Topiramate, and Flunarizine on Episodic Migraine — NCT03712917.
• Registry record last updated 2020-01-21; status last verified 2020-01.
• Results first posted 2020-01-21.
• 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 record describes a completed randomized, double-masked, parallel-group study of greater occipital nerve block, topiramate, and flunarizine for episodic migraine. Listed enrollment is 120. The planned follow-up was four weeks, with weekly recording of pain scores and attack frequency described in the brief summary.

The primary outcome is the Visual Analog Scale score at post-treatment four weeks, summarized as a mean and standard deviation on a scale from 0, no pain, to 10, worst pain. The registry record does not report outcome results, analysis results, or the statistical analysis plan.

The safety listing records zero serious adverse events and zero deaths in each group, with other adverse events affecting zero participants in the nerve-block group, 4 in the topiramate group, and 3 in the flunarizine group. Event details and comparative safety analyses are not reported in the registry record.