A Study to Test if Fremanezumab is Effective in Preventing Chronic Migraine in Participants 6 to 17 Years of Age: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study to Test if Fremanezumab is Effective in Preventing Chronic Migraine in Participants 6 to 17 Years of Age (NCT04464707), a randomized phase 3 study. The primary outcome is Mean Change From Baseline in Monthly Average Number of Migraine Days During 12-Week Period After the First Dose of Study Drug.

2. Clinical Question

3. Trial Design

This was a phase 3, multicenter, randomized, double-blind, placebo-controlled, parallel-group study of fremanezumab for preventive treatment of chronic migraine in pediatric participants aged 6 to 17 years. The registry identifies the masking as quadruple. The sponsor was Teva Branded Pharmaceutical Products R&D, Inc. The record lists enrollment of 292 and a completed study. It gives a start date of 2020-09-24 and a primary completion date of 2024-11-29.

Participants were assigned to fremanezumab or matching placebo. The fremanezumab schedule was monthly subcutaneous administration for 3 months, with dose selection based on a weight threshold. The registry record describes two dose groups, with posted safety results distinguishing fremanezumab 120 mg and fremanezumab 225 mg. For the primary efficacy endpoint, the posted results combine fremanezumab as one group and compare it with placebo.

The primary endpoint was change from baseline in monthly average migraine days over the 12-week period after the first dose. The primary time frame is described as baseline from Day -28 to Day -1, up to Week 12. Monthly averages were normalized to a 28-day equivalent using diary data. The record describes a full analysis set requiring randomization, at least 1 dose, and at least 10 postbaseline diary days for the endpoint; it also defines an intent-to-treat set as all randomized participants. The detailed analysis-population language is incomplete in the registry record.

Secondary objectives included further efficacy evaluation, safety and tolerability assessment, and immunogenicity, including the impact of antidrug antibodies on clinical outcomes. The record also lists a planned total study duration of 75 months. The detailed original sample-size justification, treatment allocation ratio, and remaining protocol specifications 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.

Before assignment: A total of 494 participants were screened; of which 292 participants were randomized and included in the analysis. As pre-specified in the Protocol and Statistical Analysis Plan, the primary and secondary efficacy analyses were conducted to compare the placebo and the pooled active arms.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The full analysis set (FAS) included all randomized participants who received at least 1 dose of study drug and had at least 10 days of diary entries postbaseline for efficacy assessments on the primary endpoint. The intent-to-treat (ITT) analysis set included all randomized participants. As pre-specified in the Protocol and Statistical Analysis Plan, the primary and secondary efficacy analyses were conducted to compare the placebo and the pooled active arms.

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: The intent-to-treat (ITT) analysis set included all randomized participants. As pre-specified in the Protocol and Statistical Analysis Plan, the primary and secondary efficacy analyses were conducted to compare the placebo and the pooled active arms.

6. Primary Endpoint

The registry lists the primary outcome as Mean Change From Baseline in Monthly Average Number of Migraine Days During 12-Week Period After the First Dose of Study Drug, measured over Baseline (Day -28 to Day -1), up to Week 12.

The primary endpoint measures the change from baseline in the monthly average number of migraine days during the 12-week period after the first dose of study drug. It is expressed in days per month. A migraine day was defined in the registry record using diary-based headache information: a day with at least 2 hours of headache and at least 2 migraine symptoms, a headache treated with migraine medication, or a headache associated with aura. The endpoint therefore reflects a defined composite of headache experience and treatment recorded in the electronic diary, rather than a simple count of all headache days.

The monthly average was normalized to a 28-day equivalent using the number of days with recorded diary assessments. This makes the outcome interpretable on a common monthly scale even when diary completion does not cover exactly the same number of days for every participant. The endpoint was analyzed as a continuous measure using an analysis of covariance, with results reported as least-squares means.

Change from baseline is used to express how the measured outcome shifted during follow-up relative to the participant’s baseline period. A negative change represents fewer migraine days during follow-up than at baseline. The group mean describes the average change, not the experience of every participant. Diary-based endpoints can capture recurring symptoms over time, but their interpretation depends on the recorded assessments and on the analysis rules for incomplete diary data. Further details of those rules are not reported in the registry record.

7. Results Posted in the Registry

• Fremanezumab: mean -3.80 versus -3.70 on control; difference -0.10 (95% CI -2.29 to 2.09), standardized effect d = -0.01; z-test p = 0.929.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Number of Participants With Abnormal Physical Examination Findings as Identified by the Investigator

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Fremanezumab 120 mg: 0.0% (0/26) versus 7.7% (11/143) on control; risk difference -7.7 percentage points (95% CI -12.1 to -3.3); unadjusted two-proportion z-test p = 0.144.
  • Fremanezumab 225 mg: 7.3% (9/123) versus 7.7% (11/143) on control; risk difference -0.4 percentage points (95% CI -6.7 to 6.0), risk ratio 0.95 (0.41–2.22); unadjusted two-proportion z-test p = 0.908.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Fremanezumab 120 mg and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Fremanezumab 225 mg and the control. The interval gives the range of effects that remain compatible with the data.

Mean Change From Baseline in Monthly Average Number of Headache Days of at Least Moderate Severity During 12-Week Period After the First Dose of Study Drug

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • Fremanezumab: mean -3.10 versus -3.80 on control; difference 0.70 (95% CI -1.43 to 2.83), standardized effect d = 0.08; z-test p = 0.520.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Fremanezumab and the control. The interval gives the range of effects that remain compatible with the data.

Number of Participants Reaching at Least 50% Reduction in the Monthly Average Number of Migraine Days During the 12-week Period After the First Dose of Study Drug

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Fremanezumab: 20.1% (30/149) versus 20.0% (28/140) on control; risk difference 0.1 percentage points (95% CI -9.1 to 9.4), risk ratio 1.01 (0.64–1.60); unadjusted two-proportion z-test p = 0.977.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Fremanezumab and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover several different domains: headache burden, migraine-day response, physical examination findings, and safety assessments. These are not interchangeable measures. Some address symptom patterns, while others describe participant counts or clinical observations during follow-up. The registry lists 13 posted secondary outcomes, but the estimates summarized in the available endpoint results cover only a subset. Further endpoint estimates are not reported in the registry record details used for this analysis.

At a broad level, the reported secondary efficacy estimates do not provide a clear, consistent contrast that changes the interpretation of the primary result. The headache-day comparison and the responder comparison are both uncertain, with their reported intervals spanning no difference. The physical-examination outcome concerns an event count rather than a direct efficacy measure and does not resolve the primary efficacy question. These patterns should be considered alongside, not in place of, the primary endpoint.

Secondary outcomes are often assessed in greater numbers than primary outcomes. If each is tested separately without a specified adjustment for multiple comparisons, the chance of finding one apparently unusual result by chance can increase. The registry record does not report a multiplicity adjustment for the posted secondary analyses. The registry also does not provide a complete statistical analysis plan for these outcomes, including whether particular comparisons were prespecified or how missing observations were handled.

For those reasons, unadjusted secondary p-values and confidence intervals carry less evidential weight than the designated primary analysis when interpreting the main trial question. They can help describe the range of outcomes considered and may identify questions for further study, but they should not be used selectively to overturn a primary result that is itself uncertain. A coherent assessment would require the complete endpoint results, analysis plan, and multiplicity strategy, none of which is fully reported in the registry record details.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Number of Participants With Treatment-Emergent Adverse Events (TEAEs)
• Number of Participants With Shift From Baseline to Last Assessment in Electrocardiogram (ECG) Findings (Assessed by Investigator)
• Number of Participants With Shift From Baseline to Last Assessment in ECG Findings (Assessed by Cardiologist)
• Number of Participants With Any One or More Potentially Clinically Significant Vital Sign Abnormalities
• Number of Participants With Potentially Clinically Significant Abnormal Laboratory (Serum Chemistry, Hematology, Coagulation, and Urinalysis) Results
• Number of Participants With Abnormal Physical Examination Findings as Identified by the Investigator
• Number of Participants With Suicidal Ideation or Suicidal Behavior as Assessed by the Columbia Suicide Severity Rating Scale (C-SSRS)
• Mean Change From Baseline in Monthly Average Number of Headache Days of at Least Moderate Severity During 12-Week Period After the First Dose of Study Drug

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous: each participant contributes a change in monthly average migraine days, and the group results are expressed as least-squares means. The registry identifies analysis of covariance (ANCOVA) as the method for the reported primary comparison. ANCOVA estimates a group contrast while accounting for covariates specified in the analysis model. The registry record does not report the full covariate list or all model details, so the adjusted result cannot be independently reproduced from the arm summaries alone.

What do least-squares means represent?

Least-squares means are model-based estimates of group averages. They can differ from simple arithmetic averages when the model adjusts for covariates or other design features. The primary result is reported as a least-squares mean difference between fremanezumab and placebo. A negative difference indicates a more negative mean change in the fremanezumab group under the stated group ordering. Because change is measured from baseline, more negative values correspond to a larger decline in monthly migraine days. This direction should not be read as a conclusion about clinical importance without considering the endpoint scale, uncertainty, and study context.

How should the confidence interval be read?

A confidence interval expresses the range of treatment differences reasonably compatible with the data and the statistical model at the stated confidence level. The reported 95% confidence interval runs from -1.48 to 1.22 days/month. It includes zero, which represents no difference in the modeled group means. Its inclusion of values on both sides of zero means that the data do not pin down the direction of the treatment contrast. A confidence interval is not a range containing every individual participant’s outcome, nor does it assign a probability to a particular treatment effect after the study is complete.

What does the p-value add?

The reported p-value is 0.848. In general, a p-value measures how unusual results at least as inconsistent with a null hypothesis would be under the assumptions of the specified statistical model, if the null hypothesis were true. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of an effect. The large p-value is consistent with the confidence interval’s inclusion of zero; neither statistic proves that there is no treatment difference.

How does the recalculation differ?

The unadjusted recalculation uses posted summary statistics to estimate a simple difference between group means and its uncertainty. It does not reproduce the registry’s ANCOVA, because individual-level data and the model’s full specification are not available in the record details. The recalculated estimate is -0.1, with an interval from -2.29 to 2.09 and p = 0.929. This is a descriptive cross-check rather than a replacement for the sponsor’s analysis. The recalculated pooled standard deviation is approximate, as indicated by the calculation description, and should be interpreted as an approximation based on the available summaries.

The registry’s reported result and the unadjusted result answer related but not identical statistical questions. One is model-adjusted, while the other is a simple comparison based on posted aggregate results. Differences in interval width and p-value can arise from adjustment and from the methods used to estimate variability. Without the full analysis data and specification, the reasons for each numerical difference cannot be separated further.

Why can dispersion matter?

For a continuous outcome, variability among participants affects how precisely a group mean and a between-group difference can be estimated. Greater variation generally makes estimates less precise when other features are held constant. The primary arm summaries report standard errors, which describe the estimated uncertainty of each group’s mean, rather than the spread of individual observations. The unadjusted recalculation estimates a pooled standard deviation from summary information and marks it as approximate. That approximate dispersion is used for the planning illustrations, not as a substitute for a fully specified model of the trial data.

For a count or binary outcome, the statistical method depends on what is being measured and how events are distributed. A participant count with an event is not the same type of measure as a continuous mean change. A risk difference compares event proportions between groups, while a mean difference compares average values on a continuous scale. The secondary physical-examination comparison is expressed as a risk difference, and the responder outcome is likewise a participant-count endpoint. Those contrasts should not be interpreted as if they were changes in migraine days.

What does the analysis population mean?

The registry describes a full analysis set that includes randomized participants who received at least 1 dose and had at least 10 days of postbaseline diary entries for primary efficacy assessment. It also describes an intent-to-treat set as all randomized participants. These definitions differ in which participants can contribute to an analysis. The remaining registry text about the intended primary analysis population is incomplete, and the handling of participants who did not meet the diary-entry requirement is not reported in the registry record. Consequently, the exact relationship between the posted estimate and each stated population definition is not fully clear from the available record.

Overall, the posted primary analysis is an adjusted comparison of modeled average changes. The confidence interval and p-value characterize uncertainty under that analysis, while the recalculated estimate is an unadjusted summary-based check. Neither method turns the observed study results into a guarantee about future participants or resolves limitations in outcome recording and analysis-population reporting.

11. Confidence Intervals and Precision

The primary reported estimate is -0.1 days/month, and its 95% confidence interval extends from -1.48 to 1.22 days/month. This interval includes zero and reaches in both directions from the point estimate. It therefore indicates that the study’s primary estimate is not highly precise with respect to the direction of the difference: the posted data are compatible with a modest difference favoring either group. The interval is for the modeled group contrast, not for individual changes.

The unadjusted recalculation has a wider interval, from -2.29 to 2.09, around the same rounded point estimate of -0.1. It is based on aggregate summaries and an approximate pooled standard deviation, and it does not reproduce the reported ANCOVA. For interpreting the trial’s primary result, the registry’s reported adjusted analysis is the relevant estimate; the recalculation is an additional view of uncertainty under a simpler approach.

Precision is distinct from statistical significance and from clinical importance. A confidence interval that includes zero does not establish no effect, while a narrow interval would not by itself establish that a difference matters to patients. The registry record does not state a threshold for a clinically important difference, so the estimates cannot be classified against such a threshold from the posted information. The confidence interval shows uncertainty in the group contrast under the reported analysis, but it does not account for every possible limitation, including incomplete reporting of missing-data handling and model details.

The group estimates are based on 140 participants in the placebo arm and 149 in the fremanezumab arm for the primary outcome. The analyzed numbers are not identical to the registry’s total enrollment, and the record describes diary-entry requirements for the full analysis set. The reason each participant was or was not included in the primary analysis is not reported in the registry record. This limits assessment of how missing or incomplete diary data may affect precision and interpretation.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size illustrations describe hypothetical future planning based on the observed effect, not the original design calculation for this trial. For continuous outcomes and participant-count outcomes, the displayed figures are participants per arm, not the total across arms. A time-to-event illustration would instead be expressed as total events, but the primary endpoint is continuous and its planning figures are participants per arm.

The stated assumptions for these illustrations are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set to a stated fraction of the observed effect. The trial’s own original sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the hypothetical number of participants per arm under which a study would have an 80% chance of detecting the specified effect using the stated assumptions, if that effect and the assumptions were correct. The 90% power column makes the analogous illustration for a 90% chance. Higher target power generally requires a larger planned sample size when other assumptions remain unchanged. The rows using 75% or 50% of the observed effect ask what planning would look like if the target effect were smaller than the observed estimate. Smaller effects are harder to distinguish from random variation, so they require more participants under these assumptions.

These calculations are planning illustrations, not observed power. They do not show the probability that the trial’s result is true or the probability that a treatment effect exists. Since the primary observed difference is close to zero, planning directly from that estimate produces very large figures; those figures should be read as a consequence of the calculation’s chosen effect input, not as a recommended trial size or as evidence about clinical relevance.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -0.100; pooled standard deviation σ = 9.509.
2. n = 2 × (1.96 + 0.842)² × 9.509² / -0.100² = 141,951.2, rounded up to 141,952 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -0.0999999999999996                      # observed difference in means
sigma <- 9.50934695142147                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(4464707)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 141,952 (80% power), 190,033 (90% power)
 75% of observed effect: n per arm = 252,358 (80% power), 337,836 (90% power)
 50% of observed effect: n per arm = 567,805 (80% power), 760,130 (90% power)
power.t.test: 141952.2 
Simulated power at n = 141,952 per arm: 0.797 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The registry’s reported primary analysis is an ANCOVA estimate of the least-squares mean difference: -0.1 days/month, with a 95% confidence interval from -1.48 to 1.22 and p = 0.848. This is the sponsor-reported analysis posted for the primary outcome. It is adjusted according to the model used for that analysis, although the full model specification is not reported in the registry record.

The recalculated comparison from posted arm summaries is also -0.1, with a confidence interval from -2.29 to 2.09 and p = 0.929. It is an unadjusted calculation and uses an approximate pooled standard deviation. It does not reproduce the ANCOVA result and should not be treated as if it did. Its purpose is to provide a summary-based comparison alongside the registry’s reported analysis.

The two analyses have similar rounded point estimates but different uncertainty intervals and p-values. Their methods and available inputs differ, so they should not be expected to match exactly. The sponsor’s analysis is the principal result for interpreting the trial’s stated primary endpoint; the recalculation is a supplementary statistical check. Neither result establishes that the groups are equivalent, and the registry record does not report enough model detail to independently reconstruct the sponsor’s analysis.

15. Multiplicity, Missing Data and Analysis Populations

The registry record identifies a primary outcome and lists multiple secondary outcomes. Testing many outcomes can increase the probability that at least one result appears statistically notable by chance, particularly when each comparison is interpreted without adjustment. The record does not report whether a multiplicity-control procedure was used for secondary outcomes, whether a hierarchy of tests was specified, or how the family of outcomes was defined. The reported secondary results should therefore be read as exploratory or descriptive unless a fuller analysis plan establishes otherwise.

The primary endpoint analysis is reported as ANCOVA, but the registry record does not give the complete model specification. It does not report the full covariate set, the detailed handling of diary observations that are missing, or the sensitivity analyses used to assess the effect of missing data. These details matter because the primary endpoint depends on electronic diary entries and because the stated full analysis set requires at least 10 postbaseline diary days.

The record defines the full analysis set as randomized participants who received at least 1 dose and had at least 10 days of postbaseline diary entries for primary efficacy assessment. It also defines an intent-to-treat set as all randomized participants. The description that follows the population definitions is incomplete, so the record does not fully clarify which population was used for the reported primary estimate or how participants outside the diary-entry requirement were handled. The reasons for missing diary data and the number of participants excluded from each analysis population are not reported in the registry record details used.

The study is described as randomized and quadruple masked, which are design features intended to support a fair comparison and reduce bias. They do not by themselves resolve uncertainty about missing outcomes, analysis choices, or multiple testing. A complete interpretation would benefit from the prespecified statistical analysis plan, the missing-data strategy, the analysis population used for each endpoint, and any multiplicity procedure. Those items are not reported in the registry record.

16. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: migraine (2.4%), status migrainosus (0.8%), anaphylactic shock (0.7%), meningitis (0.7%), headache (0.7%).

The registry posts serious adverse event figures separately for placebo, fremanezumab 120 mg, and fremanezumab 225 mg. The record lists 5 serious adverse events among 143 at risk in the placebo group, 0 among 26 at risk in the 120 mg group, and 4 among 123 at risk in the 225 mg group. It reports 0 deaths in each of these groups. These are descriptive counts from the posted safety record, not adjusted comparisons or proof that a particular treatment caused or did not cause an event.

The record also lists other adverse events separately from serious adverse events: 39 among 143 at risk for placebo, 8 among 26 at risk for fremanezumab 120 mg, and 30 among 123 at risk for fremanezumab 225 mg. The registry lists serious-event terms with reported rates, including Migraine at 2.4%, Status migrainosus at 0.8%, Anaphylactic shock at 0.7%, Meningitis at 0.7%, Headache at 0.7%, and Neurosis at 0.7%. The record details do not assign these listed terms to individual groups in this summary.

Counts depend on the number of participants at risk and the way events are coded and reported. The figures do not by themselves establish comparative safety, explain each event’s timing or outcome, or show whether an event was considered related to study drug. Further event-level detail is not reported in the registry record.

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

The primary result is an estimate of the difference between groups in mean change in monthly migraine days over the 12-week period after the first dose. The registry reports a small point estimate and a 95% confidence interval that includes zero. The result therefore does not show a clear between-group difference in this trial’s primary analysis, while the interval also leaves uncertainty about the size and direction of any underlying difference.

This finding should not be translated into a claim that the treatments are equivalent or that the true difference is exactly zero. Equivalence requires a prespecified margin and an analysis designed to assess whether the interval falls within that margin. Such a margin is not reported in the registry record. A nonsignificant p-value likewise does not establish absence of an effect; it describes the compatibility of the data with a null model under the analysis assumptions.

The mean change in each group is not the same as the treatment effect. Both groups’ posted means reflect change from baseline, but the randomized comparison is the difference between those changes. Improvements observed within a group can reflect multiple influences, including the course of symptoms and study participation, and cannot on their own identify a treatment-specific effect. The placebo group provides the trial’s concurrent comparison for that purpose.

The endpoint is based on diary records and a specific definition of a migraine day. It describes an average over the stated follow-up period, not every participant’s course, symptom severity in all respects, or long-term outcomes. The study’s treatment period is described as monthly dosing for 3 months; the primary endpoint covers the 12 weeks after first dose. These results do not establish longer-term effects or answer every question about tolerability, immunogenicity, or safety.

The record does not report a clinical-importance threshold for the primary difference, complete missing-data methods, or the full analysis model. Interpretation should therefore remain tied to the reported estimate, its uncertainty, the trial population, and the endpoint definition. The results are evidence about this randomized comparison, not individualized predictions and not medical advice.

18. Why This Trial Matters Statistically

This trial illustrates why a treatment comparison should be interpreted through the between-group estimate and its uncertainty, rather than by focusing only on changes within each arm. The posted arm means show changes from baseline, but the primary question is whether the average change differs between randomized groups. The reported least-squares mean difference is close to zero, and its interval spans both sides of zero. That combination communicates both the estimated contrast and the limits of its precision.

The contrast between an adjusted primary analysis and an unadjusted recalculation is also statistically instructive. Aggregate arm summaries can support a useful cross-check, but they cannot reproduce a model-based analysis when the full model specification and individual-level data are unavailable. A recalculation should be labeled as such and should not silently replace the analysis the trial designated for its primary endpoint.

The trial also has several outcomes across efficacy and safety domains. This makes multiplicity and prespecification important: a collection of separate results is harder to interpret when the record does not explain how testing across outcomes was managed. A coherent primary endpoint helps organize interpretation, while secondary outcomes can add context without being treated as independent confirmation of the primary finding.

Finally, sample-size illustrations based on an observed effect are not retrospective measures of whether the completed trial had adequate power. They are planning calculations whose output depends on assumptions and the chosen target effect. When the estimated effect is near zero, such illustrations can become very large and should not be mistaken for the trial’s original design justification. The record’s incomplete reporting of design assumptions, missing-data methods, and analysis details underscores the importance of transparent statistical reporting.

19. 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 registry record does not report the original sample-size justification or the assumptions used to plan enrollment. The planning illustrations based on the observed effect are separate calculations and do not fill that gap. The detailed analysis plan, full ANCOVA specification, covariates, missing-data procedures, and sensitivity analyses are also not reported in the registry record.

The primary outcome relies on electronic diary entries, and the stated full analysis set requires at least 10 days of postbaseline diary data. The record’s population description is incomplete after defining the full analysis set and intent-to-treat set. The number and characteristics of participants with insufficient diary entries, and the impact of diary incompleteness on the result, are not reported in the registry record details used.

The posted primary efficacy results combine fremanezumab into one group, while safety results distinguish 120 mg and 225 mg. This presentation does not allow a dose-specific primary efficacy comparison from the reported primary result. The record describes dose selection by weight threshold but the threshold value is not given in the details summarized for this analysis.

Some endpoint results are available in the registry record details, but the full set of secondary estimates and their analysis methods are not. The record does not report a multiplicity strategy for secondary comparisons or a clinical-importance threshold for the primary endpoint. These omissions limit assessment of how the secondary findings were selected and how large a difference would be meaningful.

Safety counts are descriptive and do not provide event-level timing, treatment attribution, or adjusted comparisons in the details. The study’s primary follow-up window is limited to 12 weeks after first dose, so the primary efficacy result does not characterize longer-term outcomes. These reporting and follow-up limitations do not negate the randomized design, but they narrow what can be concluded from the posted results.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: A Study to Test if Fremanezumab is Effective in Preventing Chronic Migraine in Participants 6 to 17 Years of Age — NCT04464707.
• Registry record last updated 2025-12-19; status last verified 2025-12.
• Results first posted 2025-12-19.
• 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.

23. Record Summary

The registry describes a completed phase 3, multicenter, randomized, quadruple-masked, placebo-controlled, parallel-group study of fremanezumab for chronic migraine prevention in participants aged 6 to 17 years. Enrollment was 292. The primary endpoint was change from baseline in monthly average migraine days over the 12-week period after the first dose.

The reported ANCOVA estimate was a least-squares mean difference of -0.1 days/month, with a 95% confidence interval from -1.48 to 1.22 and p = 0.848. The interval includes zero and allows for differences in either direction. The registry also posts secondary efficacy and safety outcomes, but the record details do not provide a complete account of analysis populations, missing-data handling, multiplicity, or the full statistical model.

The result describes this trial’s primary comparison and should not be interpreted as proof of equivalence or as a conclusion about every outcome or time horizon. The registry record is the source for the reported trial estimates; the unadjusted recalculation is supplementary and does not replace the reported analysis.