This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for IncobotulinumtoxinA (Xeomin) Versus Placebo in the Treatment of Glabellar Frown Lines (NCT00770211), a randomized phase 3 study. The primary outcome is Composite Endpoint Treatment Success (CETS) Constituted by 2 Variables: 2-point Responders at Maximum Frown (Frown as Much as Possible) at Day 30 by Investigator's Rating on the Facial Wrinkle Scale and the Patient's Assessment on 4-point Scale.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00770211 |
| Phase | Phase 3 |
| Condition | Moderate to Severe Glabellar Frown Lines |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 271 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Merz Pharmaceuticals GmbH |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned female and male participants with moderate to severe glabellar frown lines. The registry describes a planned enrollment of 255 in its summary and records enrollment of 271. The primary endpoint population was the Full Analysis Set: randomized participants who received study medication. The results record gives 182 participants in the incobotulinumtoxinA arm and 89 in the placebo arm for the primary endpoint.
Intervention
Participants assigned to the active arm received incobotulinumtoxinA (Xeomin), 20 Units, as one injection session. The registry describes the active product as botulinum toxin type A free from complexing proteins. The brief summary says participants would be followed through day 120; the primary endpoint was assessed at day 30.
Comparator
The comparator was placebo, administered by intramuscular injection as one session. The placebo description specifies a total volume of 0.5 mL and reconstitution with 0.9% NaCl. The trial used randomized allocation, double masking, and a parallel-group design.
Primary question
The primary question was whether the active arm had more participants meeting a composite treatment-success definition at day 30 than the placebo arm. Success required a 2-point improvement from baseline on both the investigator’s Facial Wrinkle Scale rating and the patient’s assessment on a 4-point scale, with both improvements occurring simultaneously. The registry’s reported analysis gives a difference in response rates of 0.48, with a 95% confidence interval from 0.40 to 0.56 and p < 0.001.
3. Trial Design
This was a Phase 3, randomized, double-blind, parallel-group, placebo-controlled trial sponsored by Merz Pharmaceuticals GmbH. The registry records the trial as completed. Its start is recorded as 2008-10 and its primary completion as 2009-03. The brief summary describes a planned 2:1 allocation to incobotulinumtoxinA or placebo, one injection session, and follow-up through day 120. The posted primary endpoint was assessed at day 30.
The registry enrollment field is 271, while the brief summary says 255 participants would be randomized. These entries describe different aspects of the registry record; the record does not explain their relationship. For the primary endpoint, the posted arm entries report 182 participants assigned to incobotulinumtoxinA and 89 assigned to placebo. The stated analysis population was the Full Analysis Set, defined as all randomized participants treated with study medication. It is not reported in the registry record whether this population definition was used for every secondary analysis.
The active intervention was incobotulinumtoxinA (Xeomin), 20 Units. The placebo was described as a matching placebo to the study powder, delivered by intramuscular injection. The registry identifies the trial as multicenter, but the number or locations of centers are not reported in the registry record. Details about how randomization was generated or concealed are also not reported in the registry record. The record identifies double masking but does not specify which roles or individuals were masked.
The brief summary describes assessment by both investigators and participants. The primary endpoint combined those perspectives rather than treating either rating alone as sufficient for success. The registry lists four secondary outcomes, involving assessments at rest and at maximum frown. The results record contains numerical entries for three of those secondary outcomes; numerical results for the remaining listed outcome 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
| Stage | IncobotulinumtoxinA (Xeomin) (20 Units) | Placebo |
|---|---|---|
| STARTED | 182 | 89 |
| COMPLETED | 181 | 87 |
| NOT COMPLETED | 1 | 2 |
Reasons for not completing this period:
| Reason | IncobotulinumtoxinA (Xeomin) (20 Units) | Placebo |
|---|---|---|
| Lost to Follow-up | 1 | 0 |
| Withdrawal by Subject | 0 | 2 |
Analysis population for the primary outcome, as defined in the registry: Full Analysis Set (FAS): All randomized subjects treated with study medication. Missing values were imputed by the evaluations made at Day 7 according to the LOCF (last observation carried forward). If no ratings for Day 7 were available values were set to 'no 2-point responder'.
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.
| Characteristic | Unit | IncobotulinumtoxinA (Xeomin) (20 Units) | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 182 | 89 | 271 | |
| Age Continuous | years | 46.9 (SD 9.32) | 45.7 (SD 11.41) | 46.5 (SD 10.05) |
| Sex: Female, Male: Female | Participants | 170 | 84 | 254 |
| Sex: Female, Male: Male | Participants | 12 | 5 | 17 |
6. Primary Endpoint
The registry lists the primary outcome as Composite Endpoint Treatment Success (CETS) Constituted by 2 Variables: 2-point Responders at Maximum Frown (Frown as Much as Possible) at Day 30 by Investigator's Rating on the Facial Wrinkle Scale and the Patient's Assessment on 4-point Scale, measured over Baseline to Day 30.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Particpants |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was a composite endpoint called Composite Endpoint Treatment Success. At day 30, a participant counted as a responder only if both the investigator’s rating on the Facial Wrinkle Scale and the patient’s assessment on a 4-point scale showed a 2-point improvement from baseline. The investigator scale ranged from none to severe. The patient scale described the participant’s ability to make muscle action, from no muscle action to strong muscle action that may cause local pallor.
Combining both ratings makes the endpoint more demanding than a response on either measure alone: the participant had to meet the improvement threshold on both assessments at the same time. It also joins an observer rating with the participant’s own assessment, so the endpoint reflects two perspectives on the change in frown lines. A composite can be useful when a trial seeks to capture more than one dimension of an outcome, but its interpretation depends on the definition of success and the choice of components. Here, the registry’s definition is explicit about the required change and the need for simultaneous improvement.
The analysis population was the Full Analysis Set: randomized participants who received study medication. For missing values, the record says day 7 evaluations were carried forward using last observation carried forward. If no day 7 rating was available, the participant was classified as not meeting the 2-point responder definition. This approach is relevant to how the day 30 composite was assigned, especially because the endpoint required usable information for both component assessments.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
For the primary composite endpoint, the registry reports 87 responders among 182 participants in the incobotulinumtoxinA arm and 0 among 89 in the placebo arm. The sponsor-reported difference in response rates is 0.48. Its 95% confidence interval runs from 0.40 to 0.56, and the reported p-value is < 0.001. These statistics describe the posted comparison for the defined day 30 composite response; they do not establish what would happen for every participant or under other conditions.
The confidence interval expresses uncertainty around the estimated difference under the analysis used. Its endpoints are both above zero, indicating that the interval is compatible with a positive difference in response rates for the active arm relative to placebo. The interval does not capture every source of uncertainty, such as possible limitations in measurement, missing-data assumptions, or trial conduct. The p-value describes how incompatible the observed data are with a null comparison under the statistical test’s assumptions; it is not the probability that the null hypothesis is true, nor a measure of the size or practical importance of an effect.
The posted secondary results also show positive unadjusted risk differences for each secondary outcome with numerical results. Their unadjusted p-values are each <0.001. The secondary outcomes use different rating criteria or conditions from the composite endpoint, so they are related evidence rather than interchangeable versions of the primary result. The registry lists four secondary outcomes, but numerical results for one are not reported in the registry record. The record does not describe a multiplicity adjustment for the collection of secondary comparisons.
The primary result is a count endpoint, and the record gives the sponsor’s Fisher Exact analysis. It does not provide a recalculated two-arm comparison for that count endpoint. For the posted secondary binary outcomes, the risk differences and associated uncertainty estimates are unadjusted recalculations from the summary counts. A recalculation is a direct summary-statistic analysis, not a substitute for a prespecified sponsor analysis; the record does not flag a discrepancy for the primary comparison.
Interpretation should remain tied to the trial’s population, endpoint, and assessment time. The primary endpoint concerns simultaneous 2-point changes in investigator and patient assessments at day 30, not every possible definition of improvement or later outcome. Although the brief summary describes follow-up through day 120, the primary result addresses day 30. The registry record does not report enough information to assess how the result might vary across subgroups, centers, or longer-term assessments.
9. Statistical Methods Explained
What does a response difference represent?
A response difference compares the proportion meeting a binary endpoint in one arm with the proportion meeting it in the other. It is expressed on the probability scale, so a positive difference means that the response proportion is higher in the arm named first in the comparison. The primary result uses the sponsor’s reported difference in response rates. The secondary results use unadjusted risk differences recalculated from the posted counts. Such differences retain the direct meaning of the outcome: whether a participant met the specified responder definition.
A risk difference is not the same as a risk ratio or an odds ratio. It gives an absolute contrast in response probabilities, whereas ratios compare relative quantities. For clinical interpretation, the absolute contrast can be especially straightforward, but it is tied to the event definition and the response proportions in the particular trial. It should not be carried over mechanically to a population with different baseline characteristics or outcome frequencies.
How should confidence intervals be read?
A confidence interval gives a range of values compatible with the observed data under a specified statistical procedure and its assumptions. Wider intervals indicate less precision than narrower intervals, all else equal. The primary analysis reports a 95% confidence interval for the difference in response rates. The secondary recalculations also include intervals for the outcomes where they are estimable. A confidence interval is not a guarantee that the true value lies within its endpoints, and it does not account for every possible source of bias or uncertainty.
The secondary risk-difference calculations are based on posted summary counts. They are unadjusted: they do not reflect a correction for examining several outcomes. Their intervals therefore describe uncertainty for the individual comparisons under their calculation approach, not the additional interpretive caution associated with multiple testing. The primary sponsor analysis is reported separately using Fisher Exact; the registry does not provide a matching recalculated interval as part of the primary count endpoint.
What does the p-value tell the reader?
A p-value measures how unusual data at least as incompatible with the null comparison would be if the null model and the test assumptions held. A small p-value is evidence against that null comparison, but it does not quantify the size of a difference, show that the endpoint is important to participants, or give the probability that the finding is due to chance. It also does not correct automatically for testing multiple outcomes. The primary p-value is reported as < 0.001; the secondary recalculations report unadjusted p-values of <0.001.
The registry identifies Fisher Exact for the sponsor’s primary analysis. This test is designed for comparisons of categorical outcomes and can be used when response counts are sparse, including a comparison with no responders in one arm. The registry does not report details such as the exact test implementation or whether any additional adjustment was used. For the secondary outcomes, the recalculations are unadjusted and should be read as descriptive inferential comparisons, not as replacements for an unreported sponsor analysis.
How should the planning illustrations be interpreted?
Planning values are illustrations based on the observed effect, not evidence about the trial’s power after it was completed. The stated assumptions are a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. The calculation considers effects set to a stated fraction of the observed effect. For example, for the investigator-rated responder outcome at rest, planning for 100% of the observed effect gives 35 participants per arm for 80% power and 46 participants per arm for 90% power. Planning for 75% of that observed effect gives 67 participants per arm for 80% power and 89 for 90% power; planning for 50% gives 160 and 213, respectively.
For the patient-rated 1-point responder outcome at rest, planning for 100% of the observed effect gives 10 participants per arm for 80% power and 12 for 90% power. Planning for 75% gives 17 and 22, and planning for 50% gives 35 and 46, respectively. These are hypothetical sample-size calculations under the stated assumptions. They are sensitive to the observed effect used as their starting point, and do not show that the original trial had a particular probability of detecting an effect. The registry record does not report the trial’s own sample-size justification.
What assumptions affect the primary endpoint?
The primary endpoint requires both component ratings to improve by the threshold at the same time. The interpretation therefore depends on how each component was assessed and on how missing component data were handled. The record says day 7 evaluations were carried forward to fill missing values at the day 30 assessment; if no day 7 ratings were available, the participant was classified as not meeting the composite responder definition. Last observation carried forward is an imputation rule, not an observed day 30 assessment. It can make the analysis depend on the earlier observation and on the assumption that this value is a suitable substitute.
The record does not report the number or pattern of missing values, nor sensitivity analyses using alternative missing-data methods. It also does not report an interim-analysis plan, a detailed statistical analysis plan, or a sample-size justification. These absences limit assessment of how robust the results are to analysis choices, but they do not change the definitions and results that the registry does report.
10. Analyses Reported by the Sponsor
| Method | Estimate | 95% CI | P-value |
|---|---|---|---|
| Fisher Exact | Difference response rate 0.48 | 0.40 to 0.56 | < 0.001 |
The sponsor’s primary analysis is the relevant reported analysis for the composite count endpoint. The registry identifies Fisher Exact as the method and reports a difference in response rates of 0.48, with a 95% confidence interval from 0.40 to 0.56 and p < 0.001. It also reports 87 responders in the incobotulinumtoxinA arm and 0 in the placebo arm. No discrepancy is flagged for this result, and no recalculated comparison is available for the primary count endpoint.
For the secondary outcomes with posted numerical results, the displayed risk differences and inferential results are unadjusted recalculations from the registry’s summary counts. These are useful as direct summaries of the posted data, but they are not the sponsor’s own reported secondary analyses: no sponsor analyses for those outcomes are listed in the record. The distinction matters because recalculations cannot reproduce analyses that may have used participant-level data, covariate adjustment, or other prespecified methods not documented in the registry. None of those additional methods should be assumed. Where a sponsor analysis is reported, it takes precedence over a simple recalculation if a discrepancy exists; the registry does not flag such a discrepancy for the primary result.
11. Multiplicity, Missing Data and Analysis Populations
The registry identifies one primary composite endpoint and lists four secondary outcomes. It reports one primary analysis. The record does not report whether the secondary outcomes were arranged in a prespecified testing hierarchy, whether family-wise error or another multiplicity procedure was used, or whether any secondary findings were intended to be confirmatory. The posted secondary recalculations are unadjusted. When numerous outcomes are examined, unadjusted p-values do not account for the increased chance of at least one small p-value arising across the collection. This is why secondary evidence generally deserves more caution than a result from a clearly designated primary endpoint.
The primary endpoint’s missing-data rule is described. The Full Analysis Set included all randomized participants treated with study medication. Missing day 30 values were imputed using the day 7 evaluation under last observation carried forward. If no day 7 ratings were available, the participant was assigned to the nonresponder category. This rule makes the endpoint definition operational even when a day 30 value is missing, but it relies on an earlier rating as a substitute and classifies participants without day 7 ratings as nonresponders. The registry does not give the amount or pattern of missingness, or sensitivity analyses testing other assumptions.
The analysis population and missing-data approach for each secondary outcome are not reported in the registry record. Nor are details of an interim-analysis plan, the trial’s sample-size justification, a full statistical analysis plan, or any adjustment strategy for the primary or secondary analyses. These omissions do not establish that such plans were absent; they mean their details cannot be assessed from the registry record. Interpretation should therefore distinguish the explicitly reported primary analysis from secondary recalculations and avoid assuming unreported analysis choices.
12. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| IncobotulinumtoxinA (Xeomin) (20 Units) | 0 | 182 | 0.0% |
| Placebo | 1 | 89 | 1.1% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 2% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| IncobotulinumtoxinA (Xeomin) (20 Units) | 35 of 182 |
| Placebo | 18 of 89 |
Most frequent serious adverse event terms
| Event term | Organ system | IncobotulinumtoxinA (Xeomin) (20 Units) | Placebo |
|---|---|---|---|
| Renal cell carcinoma | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 0 of 182 | 1 of 89 |
| Nephrectomy | Surgical and medical procedures | 0 of 182 | 1 of 89 |
Most frequent non-serious adverse event terms
| Event term | Organ system | IncobotulinumtoxinA (Xeomin) (20 Units) | Placebo |
|---|---|---|---|
| Headache | Nervous system disorders | 17 of 182 | 5 of 89 |
| Nasopharyngitis | Infections and infestations | 9 of 182 | 5 of 89 |
| Sinusitis | Infections and infestations | 6 of 182 | 4 of 89 |
| Sinus headache | Nervous system disorders | 7 of 182 | 1 of 89 |
| Pharyngitis streptococcal | Infections and infestations | 3 of 182 | 2 of 89 |
| Oropharyngeal pain | Respiratory, thoracic and mediastinal disorders | 4 of 182 | 1 of 89 |
| Upper respiratory tract infection | Infections and infestations | 4 of 182 | 0 of 89 |
| Musculoskeletal stiffness | Musculoskeletal and connective tissue disorders | 0 of 182 | 2 of 89 |
| Actinic keratosis | Skin and subcutaneous tissue disorders | 0 of 182 | 2 of 89 |
Serious events with the highest arm-level rate: renal cell carcinoma (1.1%), nephrectomy (1.1%).
The safety entries report serious adverse events in 0 participants in the incobotulinumtoxinA arm among 182 at risk and in 1 participant in the placebo arm among 89 at risk. The record also lists renal cell carcinoma and nephrectomy among the top serious adverse event terms, each with a reported frequency of 1.1%. It does not establish from these entries whether those terms refer to the same participant or how they relate to the individual arm-level event listing.
Other adverse events are reported for 35 participants in the active arm and 18 in the placebo arm, using the respective at-risk group counts shown in the record. These counts should not be interpreted as evidence that an event was caused by study treatment. The record does not provide a causal attribution analysis in the listed figures. Death counts are not reported in the registry record.
These safety figures are descriptive and should be read in the context of the trial’s size, follow-up, and event definitions. A small number of serious events cannot by itself establish or rule out differences in risk. The registry entries do not provide enough detail to assess event timing, severity beyond the serious classification, or how each event was adjudicated.
13. What the Result Does, and Does Not, Mean
The posted primary result describes a difference between randomized groups in the probability of meeting a narrowly defined day 30 composite responder criterion. It combines an investigator rating and a patient assessment and requires a 2-point improvement on both. The sponsor’s reported estimate and confidence interval quantify that contrast for this endpoint and analysis; they do not directly answer every question about changes in frown lines or about outcomes at other times.
The finding does not establish how participants would respond outside the trial population, under different assessment conditions, or over a longer period. The brief summary describes follow-up through day 120, but the primary result is for day 30. Nor does a small p-value establish clinical importance, guarantee an individual response, or show that all participants experienced the same change. The result is a group comparison under the registry’s endpoint and missing-data rules.
The secondary outcomes are directionally consistent in the numerical entries, but they are unadjusted and overlap in their outcome measures and assessment context. Their results add descriptive context without having the same confirmatory standing as the designated primary endpoint. The registry does not report numerical results for one listed secondary outcome or the details of any multiplicity plan.
Finally, the safety counts are not a complete characterization of risk. Serious adverse event and other adverse event counts are descriptive entries, and the registry record does not establish causation from those counts. The results should therefore be understood as evidence about the recorded trial comparisons, not as a guarantee of benefit or harm for any individual or as a substitute for broader evidence.
14. Why This Trial Matters Statistically
This trial is statistically notable for a composite endpoint that requires simultaneous improvement on two assessments. That definition makes the primary response criterion transparent, while also making clear that the result depends on both the investigator’s rating and the participant’s assessment. A composite endpoint is most interpretable when its components and success rule are explicit, as they are in the registry description.
The primary comparison includes no placebo responders under the posted endpoint count, which is a situation where a categorical test such as Fisher Exact is relevant. The sponsor reported that test and a confidence interval for the response-rate difference. Reporting an interval alongside a p-value helps distinguish the estimated size and precision of the comparison from the evidence against a null model.
The record also illustrates why analysis details matter. Missing day 30 values were handled by carrying forward day 7 assessments, with participants lacking day 7 ratings classified as nonresponders. That rule is part of the outcome analysis, not a neutral administrative detail. Its implications depend in part on the pattern of missingness, which is not reported.
Finally, the secondary outcomes broaden the description of response but do not all have the same inferential status as the primary endpoint. Their unadjusted tests and the absence of a reported multiplicity strategy are important when interpreting a collection of related findings. The registry distinguishes clearly enough to identify a primary result, while leaving some analysis-plan details unavailable for independent evaluation.
15. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The registry record does not explain why its enrollment field of 271 differs from the brief summary’s statement that 255 participants would be randomized. It also does not report details of the randomization sequence, allocation concealment, masking roles, or center locations. These gaps limit assessment of trial conduct from the registry entries alone.
The primary endpoint uses a specific composite definition and a day 30 assessment. The record does not report component-level missingness, the number of values imputed, or sensitivity analyses for the stated last-observation-carried-forward rule. The rule uses day 7 ratings for missing day 30 values and assigns nonresponse when day 7 ratings are unavailable, so interpretation depends in part on this handling of missing values.
The registry does not report the trial’s sample-size justification, detailed statistical analysis plan, interim analyses, or a multiplicity strategy for the secondary outcomes. Numerical results are available for three of the four listed secondary outcomes, and their recalculated comparisons are unadjusted. Their results should not be treated as if the registry documented a prespecified confirmatory testing sequence.
The safety information is also limited: counts are available for serious and other adverse events, but death counts are not reported in the registry record, and event timing, adjudication, and causal attribution details are not given in these entries. Finally, the primary result concerns day 30 even though the brief summary describes follow-up through day 120. Later outcome results are not reported in the registry record.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: IncobotulinumtoxinA (Xeomin) Versus Placebo in the Treatment of Glabellar Frown Lines — NCT00770211.
- Registry record last updated 2011-10-07; status last verified 2011-10.
- Results first posted 2011-09-13.
- 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.
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19. Record Summary
NCT00770211 is a completed Phase 3 randomized, double-blind, parallel-group, placebo-controlled trial of incobotulinumtoxinA (Xeomin), 20 Units, for moderate to severe glabellar frown lines. The brief summary describes one injection session, planned 2:1 allocation, and follow-up through day 120. The primary endpoint was a day 30 composite requiring a 2-point improvement from baseline on both investigator and patient assessments.
The registry reports 87 primary responders among 182 participants in the active arm and 0 among 89 in the placebo arm. The sponsor’s Fisher Exact analysis reports a response-rate difference of 0.48, a 95% confidence interval from 0.40 to 0.56, and p < 0.001. Three secondary outcomes have numerical results, with unadjusted recalculated comparisons; results for one listed secondary outcome are not reported in the registry record. Primary missing values were handled using day 7 evaluations carried forward, with participants lacking those ratings assigned as nonresponders.