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 Open-label Extension Study of AbobotulinumtoxinA (Dysport®) for the Treatment of Cervical Dystonia (NCT00288509), a na phase 3 study. The primary outcome is Change in Toronto Western Spasmodic Torticollis Rating Scale Total Score From Baseline.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00288509 |
| Phase | Phase 3 |
| Condition | Cervical Dystonia |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 108 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Ipsen |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned people with cervical dystonia. The intention-to-treat population consisted of all 108 subjects who received Dysport. Subjects with incomplete TWSTRS scores were not included in analyses of the total score, so the population contributing to that endpoint may be smaller; the number excluded is not reported in the registry record.
Intervention
The intervention was intramuscular botulinum toxin type A, identified in the study as Dysport. The arm description specifies 250-1000 units. The study was an open-label extension intended to assess longer-term safety and effectiveness with repeated treatment.
Comparator
There was a single-group design and no randomized comparator. Allocation is listed as not applicable, and masking is listed as none. The record therefore does not describe a concurrent control group for estimating a between-group treatment contrast.
Primary question
The primary endpoint was change in the TWSTRS total score from baseline at the Week 4 follow-up visit. The registry record does not report the mean change, its standard deviation, or an inferential result. It therefore does not establish the size or precision of the observed change.
3. Trial Design
This was a Phase III, prospective, multicenter, open-label extension study of Dysport for cervical dystonia. The registry lists the study as completed. Its recorded start was 2006-02, and its primary completion was 2008-01. The stated aim was to assess longer-term safety and effectiveness of Dysport, with repeated treatment.
The design is listed as single group, with allocation not applicable and masking none. The intervention was botulinum toxin type A, with the Dysport arm described as 250-1000 units. Because there is no randomized control arm, the study does not make a like-for-like comparison between Dysport and another intervention or control condition. Changes over time can be described, but a single-group design cannot by itself distinguish treatment-related change from other explanations for change.
The registry identifies 108 subjects who received Dysport as the intention-to-treat population. The primary outcome was a continuous measure: change in the TWSTRS total score from baseline at the Week 4 follow-up visit. The listed secondary outcomes were change from baseline in the TWSTRS Severity, Disability, and Pain subscales. The record lists four outcome measures and no analyses.
The registry record does not report the treatment schedule, the number of treatment cycles received, eligibility criteria, follow-up beyond the stated primary endpoint timeframe, or a statistical analysis plan. Those details should not be inferred from the extension-study title or the stated longer-term aim.
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: Of the 116 subjects treated in study NCT00257660, 108 subjects enrolled in this extension study NCT00288509 (Y-47-52120-731). Eight subjects completed study NCT00257660 but elected not to enroll in this extension study.
Treatment Cycle 1
| Stage | Dysport |
|---|---|
| STARTED | 108 |
| COMPLETED | 102 |
| NOT COMPLETED | 6 |
Reasons for not completing this period:
| Reason | Dysport |
|---|---|
| Adverse Event | 1 |
| Lack of Efficacy | 1 |
| Withdrawal by Subject | 1 |
| Lost to Follow-up | 2 |
| Treatment stopped according to protocol | 1 |
Treatment Cycle 2
| Stage | Dysport |
|---|---|
| STARTED | 100 |
| COMPLETED | 97 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | Dysport |
|---|---|
| Lack of Efficacy | 1 |
| Withdrawal by Subject | 2 |
Treatment Cycle 3
| Stage | Dysport |
|---|---|
| STARTED | 96 |
| COMPLETED | 91 |
| NOT COMPLETED | 5 |
Reasons for not completing this period:
| Reason | Dysport |
|---|---|
| Lack of Efficacy | 1 |
| Withdrawal by Subject | 1 |
| Lost to Follow-up | 2 |
| Treatment stopped according to protocol | 1 |
Treatment Cycle 4
| Stage | Dysport |
|---|---|
| STARTED | 88 |
| COMPLETED | 80 |
| NOT COMPLETED | 8 |
Reasons for not completing this period:
| Reason | Dysport |
|---|---|
| Withdrawal by Subject | 3 |
| Physician Decision | 4 |
| Treatment stopped according to protocol | 1 |
Analysis population for the primary outcome, as defined in the registry: The intention to treat population consisted of all 108 subjects who received Dysport. Subjects with incomplete TWSTRS scores were not included in the TWSTRS total score analyses.
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 | Dysport |
|---|---|---|
| Participants analysed | 108 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 89 |
| Age, Categorical: >=65 years | Participants | 19 |
| Age, Continuous | years | 53.5 (SD 13.0) |
| Sex: Female, Male: Female | Participants | 67 |
| Sex: Female, Male: Male | Participants | 41 |
| Region of Enrollment: United States | participants | 81 |
| Region of Enrollment: Russian Federation | participants | 27 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Toronto Western Spasmodic Torticollis Rating Scale Total Score From Baseline, measured over Week 4 follow-up visit.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | points on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change in the Toronto Western Spasmodic Torticollis Rating Scale total score from baseline to the Week 4 follow-up visit. The scale combines severity, disability, and pain. The registry describes component ranges of 0 to 35 for severity, 0 to 30 for disability, and 0 to 20 for pain; the total score ranges from 0 to 85. Lower scores represent less severity, disability, and pain on the component descriptions in the record.
For each treatment cycle, the specified change is the Week 4 score minus the baseline score. This direction matters: a negative change indicates a lower recorded total at follow-up than at baseline, while a positive change indicates a higher recorded total. That arithmetic describes score direction, not the cause of the change.
A change score is useful because it expresses how a participant’s measured score differs from their own baseline. Reporting the mean change can describe the average change in the analyzed population, while a standard deviation describes variation in individual changes. Neither statistic alone establishes whether a change is important to participants. The registry record does not state a threshold for clinical importance, nor does it report the observed mean change or its standard deviation.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The study’s stated primary outcome is a continuous measure, summarized as a mean with standard deviation. However, the registry record does not report the numerical mean change in TWSTRS total score, the standard deviation, a confidence interval, or a p-value. It therefore does not permit an assessment of the magnitude, variability, or statistical precision of the primary endpoint from the record alone. The record also lists no analyses.
The endpoint was defined as the Week 4 score minus the baseline score. In general, the sign of a mean change helps describe the direction of the average score movement, while its size describes the scale of that movement in points. The scale direction is interpretable because the component descriptions identify lower scores with absence or less of the measured feature. But a direction alone would not establish that a change was caused by treatment, and the missing numerical result means even the direction of the study’s average change cannot be stated.
The single-group, open-label design is important to interpretation. There is no randomized comparison to account for natural changes over time, changes in concomitant care, expectation effects, or other influences on ratings. Open-label assessment also means that participants and assessors were not masked, according to the registry. These design features do not invalidate the observed data, but they limit what can be attributed to the intervention.
The intention-to-treat population is described as all 108 subjects who received Dysport. The record says subjects with incomplete TWSTRS scores were excluded from total-score analyses, but does not report how many had incomplete scores or how those missing scores were handled otherwise. Consequently, the completeness of the primary-outcome analysis cannot be quantified from this record.
Safety information is reported separately from the primary endpoint. The registry lists 2 participants with serious adverse events among 108 at risk and 84 with other adverse events among 108 at risk. These counts describe events recorded during the study as categorized in the registry; they do not supply a controlled comparison or establish causation. The record gives appendicitis and nephrolithiasis as the leading serious adverse-event terms, each recorded as 0.9%. Deaths are not reported in the registry record.
In general, statistical significance and clinical importance are distinct questions. A p-value, if reported, would address compatibility with a specified statistical model and null hypothesis, not whether a change matters to participants. A confidence interval would convey uncertainty around an estimate under the analysis assumptions. Neither can be evaluated for the primary outcome from the reported information. No claim about efficacy or lack of efficacy follows from the absence of a numerical result in the registry record.
9. Statistical Methods Explained
The registry identifies the primary outcome as a mean change in a continuous measure, with standard deviation as the dispersion measure. The endpoint is the change in TWSTRS total score from baseline at the Week 4 follow-up visit. These choices describe the type of outcome and the planned summary, but do not themselves provide a result. The registry record does not report the estimated mean change or its standard deviation.
What does a mean change describe?
In general, a mean summarizes the average of observed values in an analyzed group. For a change endpoint, each value represents a follow-up score minus a baseline score. The mean therefore summarizes average score movement, rather than the follow-up score alone. The standard deviation describes how spread out individual change values are around their mean. It is not the same as a confidence interval: the former describes variation among observations, while the latter describes uncertainty about an estimated quantity under specified assumptions.
For the TWSTRS endpoint, a negative value would mean the follow-up total was lower than baseline on average; a positive value would mean it was higher. Such a direction is descriptive. It does not, in a single-group open-label study, isolate the effect of Dysport from other influences. The registry record does not provide a numerical estimate with which to assess the size or direction of average change.
Why does the scale definition matter?
The total score is composed of severity, disability, and pain subscales. The registry describes the component ranges and states that the total is their sum, with a range from 0 to 85. Knowing the scale’s construction helps interpret the unit: a change is expressed in points on the combined measure. It also helps explain why the total can reflect movement across more than one dimension. The registry record does not provide component-level results for the primary follow-up, and no component-specific contribution to any total change can be inferred.
What can an unadjusted summary establish?
In general, an unadjusted mean change describes the observed average without accounting for covariates or other factors through a model. It can be useful as a straightforward description of the analyzed group. It does not control confounding, and in a single-group study it does not estimate a randomized between-group contrast. The registry record lists no analyses, so it does not report whether any adjusted model, sensitivity analysis, or inferential procedure was used.
A confidence interval, if reported, would give a range of values compatible with the observed estimate under the model and its assumptions. Its width depends on the data and method; a narrower interval generally indicates greater statistical precision. A confidence interval is not a guarantee that the true value lies within that particular interval, and it would not remove design limitations such as the absence of a control group. No confidence interval for the primary endpoint is reported in the registry record.
A p-value, if reported, would quantify how unusual results at least as extreme as those observed would be under a specified null hypothesis and statistical model. It would not be the probability that the null hypothesis is true, nor would it establish clinical importance or causality. The registry record does not report a primary-outcome p-value or the hypothesis-testing procedure.
Why can variability affect inference?
In general, the variability of participant outcomes influences the precision of an estimated mean. Greater spread can make it harder to distinguish a mean from plausible alternative values, while less spread can support a more precise estimate when other features are comparable. The standard deviation is a description of observed spread, not a direct measure of treatment benefit. As neither the mean change nor its standard deviation is reported, the data’s observed variability and the precision of the primary estimate cannot be assessed.
Over-dispersion is a general concern when a statistical model assumes less variability than is present in the data. If that assumption is violated, standard errors and inferential conclusions can be unreliable. This is a general concept, not a reported feature of this trial: the registry record does not specify a model or report an over-dispersion assessment. It would be inappropriate to assert that over-dispersion was present or that a particular correction was used.
What do the planning illustrations mean?
In general, a sample-size illustration based on an observed effect asks how many participants per arm a hypothetical future comparison might require under stated assumptions. Such a calculation is conditional on the assumed effect, significance level, allocation, and approximation. It is a planning exercise, not an observed result and not evidence that the completed study had a particular power. The stated assumptions for planning illustrations are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. For continuous outcomes, the stated output is participants per arm. These assumptions concern hypothetical planning and do not change the actual single-group design.
The registry record does not report the numerical planning outputs or a study-specific sample-size justification. The planning assumptions therefore cannot establish what effect was considered important, what precision was sought for this study, or whether its enrollment was adequate for a particular analysis. Sample-size calculations are also sensitive to the validity of the effect and variability assumptions; this is a general limitation of planning exercises.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists the primary TWSTRS total-score change and three secondary outcomes: change from baseline in the Severity, Disability, and Pain subscales. Considering multiple outcomes can raise the general issue of multiplicity: when several hypotheses are tested, the chance of at least one apparently positive result can increase if no adjustment or prespecified testing strategy is used. The record does not report a multiplicity adjustment, a testing hierarchy, or a statistical analysis plan. It is therefore not possible to determine how multiple outcomes were handled.
The record identifies the intention-to-treat population as all 108 subjects who received Dysport. For analyses of the TWSTRS total score, it states that subjects with incomplete TWSTRS scores were not included. The number with incomplete scores, the extent of missingness at each assessment, and any reasons for missing data are not reported in the registry record. No imputation method or sensitivity analysis for missing outcomes is reported.
In general, excluding participants with incomplete outcome data can affect an estimate if the participants with missing values differ from those with complete values in ways related to their outcomes. The direction and extent of any such effect depend on the missing-data pattern and assumptions. Because the record does not quantify incomplete scores or describe additional handling, the risk cannot be characterized from the registry information alone.
The registry lists no analyses. It does not describe a per-protocol population, a modified analysis population, or another analytic set beyond the stated intention-to-treat population and the exclusion rule for incomplete total-score analyses. Conclusions about adherence to a prespecified analysis plan, robustness across populations, or missing-data sensitivity are not supported by the record.
11. 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 |
|---|---|---|---|
| Dysport | 2 | 108 | 1.9% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Dysport | 84 of 108 |
Most frequent serious adverse event terms
| Event term | Organ system | Dysport |
|---|---|---|
| Appendicitis | Infections and infestations | 1 of 108 |
| Nephrolithiasis | Renal and urinary disorders | 1 of 108 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Dysport |
|---|---|---|
| Dysphagia | Gastrointestinal disorders | 27 of 108 |
| Muscular weakness | Musculoskeletal and connective tissue disorders | 16 of 108 |
| Influenza | Infections and infestations | 10 of 108 |
| Neck pain | Musculoskeletal and connective tissue disorders | 10 of 108 |
| Urinary tract infection | Infections and infestations | 9 of 108 |
| Headache | Nervous system disorders | 7 of 108 |
| Upper respiratory tract infection | Infections and infestations | 5 of 108 |
Serious events with the highest arm-level rate: appendicitis (0.9%), nephrolithiasis (0.9%).
The registry lists 2 participants with serious adverse events among 108 at risk. It lists 84 participants with other adverse events among 108 at risk. These are separate registry categories; the counts should not be added together, since the record does not describe whether participants could appear in both categories. They are safety counts, not estimates of a comparative treatment effect.
Appendicitis and nephrolithiasis are the listed top serious adverse-event terms, each recorded as 0.9%. The record does not provide event-level detail, timing, outcome, or an assessment of whether these events were considered related to Dysport. A serious adverse event is a registry classification, and its presence alone does not establish causation.
Deaths are not reported in the registry record. This wording indicates that the record does not provide a death count; it should not be read as evidence that no deaths occurred. The open-label, single-group design also means the safety figures have no randomized comparator in this record. They describe reported occurrences in the study group, but cannot by themselves identify excess risk attributable to the intervention.
12. What the Result Does, and Does Not, Mean
The record documents a completed Phase III, open-label extension study of Dysport in cervical dystonia. It identifies the primary measure, its scale, the specified follow-up time, the intention-to-treat population, and selected safety counts. These details clarify what the study set out to assess and how the primary endpoint was defined.
The numerical primary-outcome result is not reported in the registry record. Without the mean change and its variability, it is not possible to describe the observed average score movement or its precision. The record also does not report a confidence interval or p-value. This absence should not be interpreted as evidence that there was no change, no effect, or a particular direction of effect.
The study’s single-group, open-label design means that any observed change would be descriptive rather than a randomized comparison. General influences such as the course of the condition, expectations, assessment context, or other care could also affect scores. The design does not, by itself, separate these possible influences from the effect of treatment.
The safety counts describe participants recorded as having serious or other adverse events. The registry does not provide a control group or event attribution details that would support a causal safety comparison. Likewise, the leading serious-event terms are descriptive listings and should not be interpreted as proof of a treatment relationship.
Overall, the registry establishes the study framework and some safety information, but it does not supply enough outcome reporting to judge the magnitude or statistical precision of the primary score change. No medical conclusion about benefit or lack of benefit follows from that reporting gap.
13. Why This Trial Matters Statistically
This study illustrates why design and outcome reporting matter alongside a trial’s stated aim. The registry identifies a specific continuous endpoint, the TWSTRS total-score change, and defines the calculation as follow-up minus baseline. That definition makes the score direction interpretable. Yet without the numerical estimate and its variability, readers cannot judge the size, consistency, or precision of the observed change.
The extension design also highlights the difference between monitoring outcomes over time and making a controlled treatment comparison. A single-group study can describe what happened among participants receiving the intervention, but it lacks a concurrent randomized group to help separate treatment-related change from other changes. Open-label assessment adds another interpretive consideration because participants and assessors were not masked.
Safety reporting has a distinct role. Counts of participants with serious and other adverse events help describe what was recorded, while event terms provide additional context. Without comparative data or attribution details, those records do not establish whether the intervention caused an event or changed its likelihood.
Finally, the stated planning assumptions illustrate that hypothetical sample-size calculations depend on choices about effect, allocation, and statistical method. Such illustrations are not observed power and cannot replace a study-specific justification or a reported analysis. The record does not provide a numerical primary result, analysis details, or missing-data sensitivity work. Those omissions limit the statistical conclusions that can be drawn, even though the study’s purpose and endpoint are clearly identified.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The principal limitation for statistical interpretation is that the registry record does not report the primary endpoint estimate. It specifies a mean change and standard deviation but gives neither value, and it reports no confidence interval or p-value. The numerical direction, magnitude, and precision of the primary outcome therefore cannot be evaluated from the record.
The single-group, open-label design has no randomized comparator. It can describe outcomes among participants receiving Dysport, but cannot provide a controlled estimate of treatment effect. The absence of masking may also influence subjective assessment or reporting. The record does not report assessor procedures that would clarify how these risks were managed.
For total-score analyses, participants with incomplete TWSTRS scores were excluded. The number excluded, reasons for incompleteness, timing of missing assessments, and any imputation or sensitivity approach are not reported in the registry record. The impact of missing outcomes cannot therefore be assessed.
The record lists three secondary subscale outcomes in addition to the primary endpoint, but does not describe a multiplicity strategy or analysis plan. It also lists no analyses, so model choices, covariate adjustment, and robustness checks are not reported. Treatment scheduling and the number of cycles are not reported in the registry record, limiting interpretation of the longer-term repeated-treatment aim. Safety counts are descriptive and lack a concurrent comparator and reported event-attribution details.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Open-label Extension Study of AbobotulinumtoxinA (Dysport®) for the Treatment of Cervical Dystonia — NCT00288509.
- Registry record last updated 2022-09-28; status last verified 2022-09.
- Results first posted 2010-04-02.
- 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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18. Record Summary
NCT00288509 is a completed Phase III, prospective, multicenter, open-label extension study of Dysport for cervical dystonia. The registry describes a single-group design with no masking and an intervention of botulinum toxin type A at 250-1000 units. The stated aim was to assess longer-term safety and effectiveness with repeated treatment.
The primary endpoint was change in TWSTRS total score from baseline at the Week 4 follow-up visit. The intention-to-treat population consisted of all 108 subjects who received Dysport; subjects with incomplete TWSTRS scores were excluded from total-score analyses. The primary numerical result and statistical analyses are not reported in the registry record.
The registry lists 2 participants with serious adverse events and 84 with other adverse events, each among 108 at risk. Appendicitis and nephrolithiasis are listed among the leading serious-event terms at 0.9% each. Deaths are not reported in the registry record.