BG00012 Monotherapy Safety and Efficacy Extension Study in Multiple Sclerosis (MS): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for BG00012 Monotherapy Safety and Efficacy Extension Study in Multiple Sclerosis (MS) (NCT00835770), a randomized phase 3 study. The primary outcome is Number of Participants With Treatment-Emergent Adverse Events (AEs).

2. Clinical Question

The study’s primary objective was to evaluate long-term safety. Secondary objectives included clinical relapse outcomes, disability progression, MRI measures in participants with prior MRI scans in earlier studies, health economics assessments, and visual function. The posted primary comparison concerns overall treatment-emergent adverse events, while the secondary outcomes address different aspects of disease activity and function.

The central statistical question is whether the observed difference in the proportion of participants with at least one treatment-emergent adverse event is estimated precisely enough to distinguish the two dosing schedules. The registry reports counts and an unadjusted comparison. The interval around that comparison includes values on either side of no difference, so the estimate is compatible with more events in either group as well as little difference. This is a description of the posted evidence, not a treatment recommendation or a causal conclusion.

3. Trial Design

This was a Phase 3 randomized, double-masked, parallel-group extension study. The registry lists enrollment as 1,736. The study title describes a dose-blind, multicenter extension, and the posted record marks the study as completed. Its stated purpose was to evaluate long-term safety and efficacy of two BG00012 monotherapy doses in people with relapsing-remitting multiple sclerosis.

During the first phase, the BID group received BG00012 240 mg twice a day and placebo capsules once a day. The TID group received BG00012 240 mg three times a day. In the second phase, both groups received open-label BG00012 240 mg twice a day for at least 8 years. Thus, the randomized dose schedules distinguish the first phase, while the subsequent phase used the same open-label dose schedule in both groups.

The primary safety outcome covers Day 1 up to Week 561. The secondary outcomes include relapse measures and MRI and disability measures, with the posted relapse outcomes covering Day 1 up to Week 384. Secondary results are divided by prior treatment history, including earlier BG00012 schedules, matched placebo, and glatiramer acetate. Those subgroups are not interchangeable: their prior treatment differs, and their reported participant counts differ.

The registry record does not report the original sample-size justification, the detailed randomization procedure, or the full statistical analysis plan. Interim analyses are not reported in the registry record. The record also does not give a complete account of eligibility, adherence, treatment discontinuation, or the handling of missing outcome data. These gaps limit how fully the design and analysis can be reconstructed from the registry entry alone.

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: The study included participants who completed studies NCT00420212 and NCT00451451. A total of 1736 participants were treated in the open label phase extension study NCT00835770, out of which 759 completed the study.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Safety population included all participants who had any post-baseline safety follow-up in study NCT00835770, defined as any treatment emergent AE in study NCT00835770 or any post-baseline laboratory, vital signs, or physical exam assessment in study NCT00835770, and received at least one dose of study treatment in study NCT00835770.

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: Intent-to-Treat (ITT) population included participants who had entered study NCT00835770 and received at least one dose of study treatment. Data for ethnicity was not evaluated in the study.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Treatment-Emergent Adverse Events (AEs), measured over Day 1 up to Week 561.

The primary endpoint is the number of participants with treatment-emergent adverse events, counted from Day 1 up to Week 561. The registry defines an adverse event broadly as an untoward medical occurrence in a participant administered a pharmaceutical product, whether or not the event is judged to have a causal relationship with treatment. Accordingly, this endpoint records events occurring during the defined period; it does not by itself identify events caused by BG00012.

The posted result is a participant count for each group, with the group denominator also reported. The comparison is expressed as a risk difference: the estimated event proportion in the TID group minus the estimated event proportion in the BID group. A value below zero therefore represents a lower observed proportion in the TID group, using this comparison’s direction. The registry reports a risk difference of -0.011, with an interval from -0.033 to 0.010 and an unadjusted p-value of 0.298.

Counting participants with at least one event is useful for summarizing how many people experienced an event, but it does not capture how often events recurred or how long they lasted. Nor does this single broad endpoint describe the seriousness, type, or cause of every event. Separate serious-event summaries and event terms add context, but they do not replace the primary endpoint or establish causality.

7. Results Posted in the Registry

• BG00012 240 mg TID: 93.8% (814/868) versus 94.9% (824/868) on control; risk difference -1.2 percentage points (95% CI -3.3 to 1.0), risk ratio 0.99 (0.97–1.01); unadjusted two-proportion z-test p = 0.298.

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.

Percentage of Participants Who Had Relapses

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • BG00012 240 mg BID (Prior BG00012 240 mg BID): 39.9% (200/501) versus 34.1% (85/249) on control; risk difference 5.8 percentage points (95% CI -1.5 to 13.1), risk ratio 1.17 (0.95–1.43); unadjusted two-proportion z-test p = 0.124.
  • BG00012 240 mg TID (Prior BG00012 240 mg TID): 41.0% (206/502) versus 34.1% (85/249) on control; risk difference 6.9 percentage points (95% CI -0.4 to 14.2), risk ratio 1.20 (0.98–1.47); unadjusted two-proportion z-test p = 0.068.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between BG00012 240 mg BID (Prior BG00012 240 mg BID) 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 BG00012 240 mg TID (Prior BG00012 240 mg TID) and the control. The interval gives the range of effects that remain compatible with the data.

Annualized Relapse Rate (ARR)

• Endpoint type: Event rate: events per unit of follow-up, compared as a rate ratio.
• Test: Poisson rate ratio, based on the estimated number of events and follow-up time.
• Result:
  • BG00012 240 mg BID (Prior BG00012 240 mg BID): 0.16 versus 0.20 (relapses per participant-years) on control; rate ratio 0.79 (95% CI 0.00–690.41, approximate, Poisson model); p ≈ 0.947.
  • BG00012 240 mg TID (Prior BG00012 240 mg TID): 0.18 versus 0.20 (relapses per participant-years) on control; rate ratio 0.89 (95% CI 0.00–669.41, approximate, Poisson model); p ≈ 0.974.
• Interpretation:
  • The 95% confidence interval includes no difference (a ratio of 1), so these data do not show a statistically significant difference between BG00012 240 mg BID (Prior BG00012 240 mg BID) and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference (a ratio of 1), so these data do not show a statistically significant difference between BG00012 240 mg TID (Prior BG00012 240 mg TID) and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes broaden the focus beyond the primary count of participants with treatment-emergent adverse events. They include relapse occurrence, annualized relapse rate, disability change, and MRI lesion measures. The posted results include values for relapse outcomes by prior treatment history, while the registry lists a wider set of secondary outcome measures. The registry record does not report posted results for every listed outcome in the information available.

Across the relapse outcomes, the group values are not all alike, and their comparison depends on the treatment participants received before entering this extension. The prior-treatment categories include BG00012, matched placebo, and glatiramer acetate. Because these are distinct histories and the numbers of participants vary among categories, the results should not be collapsed into one simple contrast or treated as if every group began from the same background.

These outcomes relate to the primary result by addressing different dimensions of the study, not by confirming or contradicting the safety endpoint. The primary endpoint counts participants with any treatment-emergent adverse event over its safety timeframe. Relapse outcomes describe disease events, and MRI or disability outcomes assess other clinical or imaging measures. Agreement across different measures could be informative, but the registry does not provide a complete, prespecified synthesis of them.

Unadjusted secondary results carry less weight because many outcomes and subgroup comparisons create multiple opportunities for apparently notable estimates. The registry record does not report a multiplicity strategy, complete analysis plan, or sponsor-reported statistical analyses for the posted secondary comparisons. The comparisons should therefore be treated as descriptive or exploratory, with their uncertainty and differing prior-treatment histories kept in view. They do not establish a broad efficacy conclusion or resolve the primary safety comparison.

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

• Percentage of Participants Who Had Relapses
• Annualized Relapse Rate (ARR)
• Change From Baseline in the Expanded Disability Status Scale (EDSS) at Week 384
• Number of Gadolinium (Gd)-Enhancing Lesions as Measured by Magnetic Resonance Imaging (MRI)
• Volume of Gd-Enhancing Lesions as Measured by Magnetic Resonance Imaging (MRI)
• Number of New or Newly Enlarging T2 Lesions as Measured by Magnetic Resonance Imaging (MRI)
• Volume of New or Newly Enlarging T2 Lesions as Measured by Magnetic Resonance Imaging (MRI)
• Number of T1 Hypointense Lesions as Measured by Magnetic Resonance Imaging (MRI)

9. Statistical Interpretation

10. Statistical Methods Explained

For the primary endpoint, each group’s result is a count of participants with at least one treatment-emergent adverse event, alongside the number of participants in that group. The comparison uses a risk difference, defined generally as one group’s event proportion minus the comparator group’s event proportion. In this comparison, the TID group is contrasted with the BID group. A negative estimate indicates a lower observed proportion in the TID group; a positive estimate indicates a higher observed proportion.

The reported primary risk difference is -0.011. Its interval runs from -0.033 to 0.010. In general, a confidence interval describes a range of values compatible with the data under the calculation’s assumptions. The interval is more informative than the point estimate alone because it shows the range of uncertainty around that estimate. The interval level is not reported in the registry record, so it should not be assigned a confidence percentage based on the entry.

The registry also gives an unadjusted p-value for the primary comparison. In general, a p-value measures how unusual the observed data, or data more extreme, would be under a specified null model. It is not the probability that the null hypothesis is true, nor is it a measure of effect size. The p-value is labelled unadjusted, and the record does not provide a multiplicity adjustment for the primary and secondary outcomes.

Binary secondary outcomes, such as whether a participant had a relapse, can also be compared using a risk difference. The posted comparisons use the prior matched-placebo group as the reference for the listed BG00012 histories. The registry reports unadjusted comparisons, but it does not list sponsor-reported analyses for these outcomes. Any comparisons calculated from the posted group summaries are consequently unadjusted recalculations, not a substitute for a prespecified sponsor analysis.

Annualized relapse rate is a rate rather than a simple proportion. Generally, a rate relates the number of events to the time participants are observed, allowing follow-up time to differ. A rate ratio compares two such rates. The posted rate ratios are accompanied by very wide intervals, including 0.001 to 690.4 for the prior BID comparison and 0.001 to 669.4 for the prior TID comparison. Those intervals communicate substantial uncertainty in the rate-ratio estimates. The registry identifies a Poisson calculation for these comparisons; generally, a Poisson model is used for event counts over exposure time and relies on assumptions about the event-count process. Over-dispersion matters in general because event counts can vary more than a Poisson model expects, making model-based uncertainty too narrow if extra variation is ignored. The registry record does not report whether over-dispersion was assessed or how it was handled.

For the primary endpoint, the posted group counts are the observed results. The additional sample-size illustrations use an assumed effect based on a fraction of the observed effect and specified planning assumptions. They are not the trial’s original design calculations. In general, a planning calculation asks how many participants might be needed under a chosen model and assumptions to detect a stated effect. Its answer depends on the assumed effect, error rate, allocation, and method. A planning figure is not evidence that the study had a particular probability of detecting an effect after the results were observed.

The registry describes the primary safety population as participants with post-baseline safety follow-up and at least one dose, but its final text is truncated. The record does not report a complete missing-data method, a detailed account of exclusions by outcome, or a complete description of analysis populations for all secondary outcomes. These details matter because the interpretation of a count or rate depends on who was included and how absent follow-up was treated.

In general, randomized comparisons are intended to reduce systematic differences between groups at assignment. That benefit does not resolve every issue in an extension study: later follow-up, open-label treatment, incomplete data, and subgrouping by prior treatment can affect how estimates should be interpreted. The registry record does not describe the detailed randomization process or provide enough analysis-plan information to assess all such issues. The posted estimates should therefore be read as the results and comparisons recorded, with their stated limitations, rather than as a complete account of the study’s analysis.

11. Confidence Intervals and Precision

The primary risk-difference estimate is -0.011, and its interval extends from -0.033 to 0.010. Because the interval includes zero, the posted estimate is compatible with no difference as well as with differences in either direction. Its width also means the result does not pin down a single precise value for the between-group contrast. The registry record does not report the interval’s confidence level.

Precision is not the same as importance. A narrow interval would indicate less statistical uncertainty, but whether a difference matters clinically requires context and a threshold that the registry does not report. A p-value does not replace the interval: p = 0.298 summarizes the primary comparison under its null model, while the estimate and interval convey the direction and range of the effect estimate.

Precision is notably limited for the posted annualized relapse rate comparisons. Their rate-ratio intervals extend from very small values to hundreds, indicating that those estimates do not sharply determine the relative rates. The registry’s rate calculations also depend on exposure time, and the posted comparison details describe the time source as derived from the outcome timeframe. The record does not provide enough detail to assess how that time construction affects the uncertainty.

The secondary relapse-proportion comparisons also have intervals that include zero: -0.015 to 0.131 for the prior BID comparison, and -0.004 to 0.142 for the prior TID comparison. These estimates are unadjusted and arise among multiple outcomes and prior-treatment groups. The interval level is not specified in the record. Taken together, the posted uncertainty argues for cautious interpretation rather than a definitive ranking of the dosing schedules.

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 planning illustrations estimate participants per arm for the binary outcomes and rate outcomes. The record’s general convention says time-to-event illustrations give total events, but the listed outcomes are not described as time-to-event outcomes; their planning figures are participants per arm. The original trial’s own sample-size assumptions and justification are not reported in the registry record.

The planning assumptions 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 the stated fraction of the observed effect. The illustration uses the observed effect as its starting point, then also considers planning for 75% and 50% of that effect. These are hypothetical planning scenarios rather than features of the original trial design.

The 80% power column gives the estimated participants per arm under those assumptions for a design with an 80% chance of detecting the selected effect if that effect were the true one. The 90% power column uses the same idea with a higher target chance of detection, which generally requires more participants for a given assumed effect. These calculations do not report how likely the completed study was to detect a real effect.

Smaller effects are harder to detect, so planning for a smaller fraction of the observed effect requires more participants per arm. For example, the primary endpoint illustration lists 6,299 participants per arm for 80% power at 100% of the observed effect and 23,985 participants per arm for 80% power at 50% of the observed effect. These values illustrate how strongly a planning estimate can depend on the effect assumed. They are not observed power, and they should not be read as a retrospective score for the trial.

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, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.949; treatment proportion p₁ = 0.938; average p̄ = 0.944.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.3264 = 0.6397.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.3263 = 0.2746.
4. n = (0.6397 + 0.2746)² / (-0.0115)² = 6,298.5, rounded up to 6,299 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
p0 <- 0.949308755760369                          # control proportion
p1 <- 0.93778801843318                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^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 (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(835770)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 6,299 (80% power), 8,432 (90% power)
 75% of observed effect: n per arm = 10,930 (80% power), 14,631 (90% power)
 50% of observed effect: n per arm = 23,985 (80% power), 32,109 (90% power)
power.prop.test: 6298.5 
Simulated power at n = 6,299 per arm: 0.796 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-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. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary safety endpoint and numerous secondary outcome measures, including relapse, disability, and MRI outcomes. When several outcomes and comparisons are examined, the chance of obtaining an apparently notable result by chance can increase. Statistical plans commonly address this issue through a prespecified hierarchy or adjustment, but the registry record does not report whether either approach was used.

The posted secondary comparisons are unadjusted, and no sponsor-reported analyses are listed for them. That makes their p-values, where posted, less persuasive as confirmatory evidence when interpreted across the wider set of outcomes. The record also does not describe whether the secondary outcomes were prespecified in a hierarchy, whether any endpoint was designated for formal testing after the primary endpoint, or how the family of comparisons was defined. Those details are not reported in the registry record.

Missing-data handling is also not reported in sufficient detail. The primary safety population definition refers to post-baseline safety follow-up and at least one dose, but the registry text is truncated. The record does not state how participants without later assessments were treated, whether outcome-specific analysis populations were used, or what methods were applied to incomplete follow-up. For long-term outcomes, the amount and pattern of missing information can affect estimates and their precision.

The record does not report interim analyses or stopping rules. It also does not describe whether subgroup analyses were planned in advance or how the prior-treatment categories were handled statistically. These absences do not show that an analysis was or was not performed; they mean its methods cannot be established from the registry entry. Consequently, the primary comparison can be described using the posted estimate and interval, while claims from multiple unadjusted secondary comparisons require particular restraint.

15. 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: multiple sclerosis relapse (14.1%), fall (2.1%), urinary tract infection (1.2%), breast cancer (0.9%), cholelithiasis (0.8%).

The serious adverse event summary reports 279 affected participants among 868 at risk in the BID group and 272 among 868 at risk in the TID group. These are participant counts, not counts of every serious event; the registry does not present the serious-event totals in this summary. The primary treatment-emergent adverse event endpoint is broader and counts participants with any qualifying event, not only serious events.

The registry lists “Multiple sclerosis relapse” at 14.1% among the top serious-event terms, followed by fall at 2.1%, urinary tract infection at 1.2%, breast cancer at 0.9%, cholelithiasis at 0.8%, and pneumonia at 0.7%. These are listed terms and percentages; the entry does not provide enough context to infer causation or compare each term between groups.

The record reports 5 deaths in the BID group and 6 in the TID group. These counts alone do not establish that treatment caused or prevented any death. The registry’s broad adverse-event definition explicitly does not require a causal relationship with treatment. Interpretation of serious events also depends on timing, clinical review, exposure, and follow-up details that are not fully reported in the registry record.

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

The primary result describes the proportion of participants in each dosing group who had at least one treatment-emergent adverse event during the specified safety follow-up. The posted risk-difference estimate is slightly below zero for TID relative to BID, but its interval crosses zero. The result therefore does not clearly establish a difference between these groups in the broad participant-level endpoint.

That conclusion is limited to this outcome, the stated safety population, and the reported follow-up. It does not show that every adverse event was caused by BG00012, nor does it summarize event frequency, duration, severity, or the experience of participants who may not be represented in the safety analysis. The serious-event summaries and listed terms add descriptive context but do not resolve causality.

The result also does not compare BG00012 with placebo for the primary endpoint. The primary safety groups are the BG00012 240 mg BID and BG00012 240 mg TID schedules. Although placebo appears in the description of the first phase and in prior-treatment histories for secondary results, it is not the comparator in the posted primary safety comparison.

Secondary relapse findings address separate questions and are divided by prior treatment. Their unadjusted nature, varying subgroup histories, and broad uncertainty mean they should not be used as definitive evidence of comparative efficacy. The record does not provide a complete analysis plan, missing-data methods, or multiplicity strategy. A statistically careful reading therefore distinguishes the observed values from causal or general claims that the registry does not support.

Overall, the registry supports reporting the observed event counts and their estimated contrast, along with the uncertainty around that contrast. It does not establish that the schedules are equivalent, that one schedule is safer, or that either schedule has a particular clinical effect. Such conclusions would require design, analysis, and clinical context beyond what is reported in the registry entry.

17. Why This Trial Matters Statistically

This extension study is statistically notable because its central endpoint concerns long-term safety, while the planned treatment phases differ in masking and dose schedule. The first phase distinguishes BID from TID dosing, and the second phase is described as open-label BG00012 240 mg BID in both groups for at least 8 years. Understanding which phase and follow-up period an outcome covers is essential when interpreting a long-term extension.

The primary result illustrates why an estimate should be read together with its interval. The observed participant counts are close, but the main statistical point is not the apparent closeness of the raw counts; it is the estimated difference and the uncertainty around it. The interval includes zero, so the registry result does not sharply separate the schedules on the broad adverse-event endpoint.

The study also illustrates the distinction between a primary endpoint and multiple secondary outcomes. Safety, relapse, disability, and MRI measures describe different questions. Subgrouping secondary results by prior treatment adds further complexity, and unadjusted comparisons do not automatically provide confirmatory evidence across that collection of outcomes. The registry’s lack of reported multiplicity and missing-data methods makes disciplined interpretation especially important.

Finally, the planning illustrations make clear that sample-size requirements depend strongly on the effect selected for detection. Those figures are scenarios based on observed effects and stated assumptions, not evidence about the trial’s original design or the chance that it detected an effect. Keeping observed results, uncertainty intervals, exploratory comparisons, and planning calculations separate is central to sound statistical interpretation.

18. 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’s primary population description is truncated, ending before its full eligibility wording is complete. Although the record identifies a safety population and reports the group counts, it does not fully explain how participants with incomplete follow-up or missing assessments were handled. This limits assessment of the endpoint population and the possible effect of missing data.

The study is an extension with two described phases: an initial dose-blind comparison of BID and TID schedules followed by open-label BG00012 240 mg BID in both groups for at least 8 years. The primary endpoint spans Day 1 up to Week 561, while posted relapse outcomes span Day 1 up to Week 384. This difference in outcome windows makes direct cross-endpoint comparisons difficult, and the registry does not provide enough detail to reconstruct exposure and follow-up for every outcome.

Secondary results are separated by prior treatment history, including BG00012 schedules, matched placebo, and glatiramer acetate. Differences among these histories and subgroup sizes complicate interpretation of cross-group patterns. The registry does not report whether these subgroup comparisons were planned, nor does it list sponsor-reported inferential analyses for the posted relapse outcomes.

The record also lacks the original sample-size justification, detailed statistical analysis plan, multiplicity strategy, interim analysis information, and full missing-data methods. It does not give a complete account of adherence, discontinuation, or outcome-specific analysis populations. These are limitations of what the registry entry reports; they do not by themselves establish that the study lacked such procedures.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: BG00012 Monotherapy Safety and Efficacy Extension Study in Multiple Sclerosis (MS) — NCT00835770.
• Registry record last updated 2020-12-31; status last verified 2020-12.
• Results first posted 2020-12-31.
• 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.

22. Record Summary

The registry describes a completed randomized, double-masked, parallel-group Phase 3 extension study of BG00012 monotherapy in relapsing-remitting multiple sclerosis, with enrollment of 1,736. Its primary objective was long-term safety. The main posted endpoint counts participants with treatment-emergent adverse events from Day 1 up to Week 561.

The primary comparison is between BG00012 240 mg BID and BG00012 240 mg TID. The posted risk difference is -0.011, with an interval from -0.033 to 0.010 and an unadjusted p-value of 0.298. The interval includes zero, so the estimate does not clearly distinguish the schedules on this endpoint.

Secondary outcomes include relapse, disability, and MRI measures. Relapse results are divided by prior treatment history; the registry does not report sponsor analyses for the posted secondary comparisons, and multiplicity and missing-data methods are not reported. Interpretation should remain tied to the specific outcomes, groups, and follow-up periods recorded.