Dysport in Post-Surgical Neuralgia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Dysport in Post-Surgical Neuralgia (NCT03663101), a randomized phase 2 study. The primary outcome is Time to Onset of Effect in the Spontaneous Numerical Rating Scale (NRS) Score.

2. Clinical Question

3. Trial Design

This was a Phase 2, randomized, double-blind, parallel-group study sponsored by Ipsen. The registry lists enrollment of 16 and study status as completed. The study start date was 2018-10-30, and primary completion was 2019-11-08. It concerned chronic scar pain, specifically pain around abdominal or thoracic surgical scars.

The study had a pre-randomization run-in, identified as Part A, followed by the double-blind randomized period, Part B. In Part A, participants received either saline or lidocaine as Test 1, then crossed over to the other agent as Test 2 one week later. This was a comparison within the run-in; the registry describes Part B separately as a parallel-group comparison.

In Part B, the study arms were three single-dose, intradermal Dysport injections and a single-dose, intradermal saline placebo. The adverse-event groups label the Dysport doses as 2.5 U, 10 U and 20 U per injection site. The registry describes the study as double-blind and randomized but does not report details of the randomization procedure, allocation concealment, or which study personnel were masked.

Enrollment of 16 is the registry’s overall enrollment figure; it should not be treated as the number analyzed for every outcome. The primary-outcome population was defined as randomized participants who reached the time to onset, and the safety groups have different numbers at risk. The registry record does not report a rationale for the planned enrollment or a detailed participant flow.

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: Part A was conducted to identify participants who would potentially benefit from Dysport® injection, considered as 'responders'. Part B was a double-blind study of Dysport or placebo injection in responders from Part A. Of the 46 participants who were included in Part A, 17 were responders. Of which, 16 participants were randomised into Part B of the study.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Randomised population included all participants randomised in the double-blind period (Part B). Only participants who reached the time to onset were analysed.

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: Randomised population included all participants randomised in the double-blind period (Part B).

6. Primary Endpoint

The registry lists the primary outcome as Time to Onset of Effect in the Spontaneous Numerical Rating Scale (NRS) Score, measured over Part B: From baseline (defined as mean of all predose data from Day -7 and including predose on Day 1) up to end of study (Week 16) or early discontinuation..

The primary endpoint was time to onset of effect on the spontaneous Numerical Rating Scale (NRS) score, measured in days. Onset was defined as the time until a participant’s spontaneous NRS score decreased by two points or more from baseline. The NRS ranged from 0 to 10, with 0 meaning no pain and 10 meaning worst possible pain.

Baseline was defined as the mean of all predose data from Day -7 and the predose measurement on Day 1. The assessment period extended from baseline through Week 16 or early discontinuation. Participants used an Actiwatch to record spontaneous pain at home. The device prompted recordings twice a day, asking participants to rate their average and worst pain over the preceding 12 hours.

Time to onset captures how long it takes to meet a prespecified change threshold, rather than the size of every pain score change over time. It can therefore describe the timing of a response under the endpoint definition. The registry says only descriptive statistical analysis was performed for this outcome. It does not report the group-level time-to-onset values, variability, or participant counts contributing to those values.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does time to onset measure?

Time-to-event outcomes measure the time until a defined event occurs. In this study, the event was not a diagnosis or a general judgment of improvement; it was the first qualifying decrease in spontaneous NRS from baseline, defined as a decrease of two points or more. The outcome was expressed in days, with follow-up running from baseline to Week 16 or early discontinuation.

For this type of outcome, the definition of the event and the way observations over time are handled are important. A participant’s recorded pain score may vary across assessments, and the endpoint requires identifying when the threshold is met. The registry gives the threshold and measurement schedule, but does not report further rules for confirming onset or handling incomplete recording histories. Those details are not reported in the registry record.

Why can not-yet-observed events matter?

In general, a time-to-event analysis must account for participants whose event is not observed during follow-up. Such observations can be censored: the participant contributes information up to the last time they are known to be event-free, without being counted as having experienced the event. That approach depends on clear rules for the end of observation and on a specified analysis method.

The registry states that only participants who reached time to onset were analyzed for the primary measure and that only descriptive statistical analysis was performed. It does not describe how participants who did not reach onset were treated, whether any censoring method was used, or how early discontinuation affected the calculation. Since this endpoint’s reported analysis is descriptive and the underlying values are absent, no time-to-event curve, hazard estimate, or treatment comparison can be inferred from the record.

What do a mean and standard deviation convey?

The primary endpoint is described using a mean and standard deviation. In general, the mean gives the arithmetic average of observed times, while the standard deviation describes how dispersed those times are around their average. These summaries do not, by themselves, show the shape of the data or quantify uncertainty in the mean. A confidence interval, if reported, would represent a range of values compatible with the data and the interval’s statistical procedure; no confidence interval for this endpoint is reported in the registry record.

Time-to-event data may not be well represented by a simple mean and standard deviation when some participants have not experienced the event by the end of observation. A survival-analysis approach can incorporate incomplete follow-up, but its suitability and interpretation depend on the analysis plan and observed data. The registry does not report a survival-analysis method for the primary outcome; it expressly states that the outcome received descriptive statistical analysis only.

What does the planning illustration mean?

The registry’s planning assumptions describe an illustration based on an observed effect, not the study’s original design justification. In general, a sample-size calculation asks how many participants would be needed to detect a specified effect under chosen assumptions about the significance level, allocation, and statistical model. Such a calculation is not a measure of the evidence actually observed in a completed trial.

The stated illustration uses a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. For time-to-event outcomes, the illustration is described in terms of total events using the Schoenfeld method; other outcomes are described in participants per arm. These are planning conventions, not observed outcomes or evidence that the study had a particular probability of detecting an effect.

The registry record does not report the trial’s own sample-size justification, and the primary outcome was not reduced to a single comparison in the planning material. Therefore, an illustrative calculation cannot be treated as the planned enrollment rationale or as observed power. The listed enrollment remains 16; no power conclusion follows from that figure alone.

What is the role of randomization and masking?

Random allocation is intended, in general, to reduce systematic differences between treatment groups by assigning participants through a chance-based process. Double masking is intended to limit the influence of treatment knowledge on participant reports and study conduct. Those design features are relevant in a study where participants report pain scores, but the registry does not provide procedural details about sequence generation, concealment, or who was masked. The record labels the study randomized and double-blind; it does not allow further assessment of implementation.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists six outcome measures, including the primary time-to-onset measure and secondary changes in spontaneous and stimulus-evoked NRS scores. The secondary outcomes include change from baseline in spontaneous NRS throughout the study and change from baseline in stimulus-evoked NRS on the painful area at Weeks 6 and 12. The registry reports zero analyses, and numerical outcome results or statistical comparisons are not reported in the registry record.

Multiplicity arises in general when several outcomes, time points, doses, or statistical comparisons are examined. Without a prespecified testing hierarchy or adjustment strategy, repeated inferential testing can increase the chance of at least one apparently notable result by chance. The registry record does not report a multiplicity procedure, a hierarchy among outcomes, or a full statistical analysis plan. It is therefore not possible to determine how multiple outcomes or dose comparisons were intended to be interpreted.

The primary-outcome population is described as all participants randomized in Part B, with only participants who reached time to onset analyzed. The record does not report how many participants met that condition in each arm. It also does not report the handling of participants without an observed onset, missing NRS records, early discontinuations, or other missing data. The term “all participants randomized” describes the stated population definition, but the restriction to participants reaching onset means the analyzed set may be narrower. The record does not give enough detail to assess the resulting analysis population or missing-data assumptions.

These omissions limit assessment of whether the reported results, if available elsewhere, would reflect the original randomized groups and how uncertainty from multiple comparisons was addressed. They do not establish that any particular method was or was not used outside what the registry record reports.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: pancreatogenous diabetes (33.3%).

The safety groups list participants at risk and participants affected by serious and other adverse events. For serious adverse events, the record reports 0 of 4 for placebo, 1 of 3 for Dysport 2.5 U/Injection Site, 0 of 5 for Dysport 10 U/Injection Site, and 0 of 4 for Dysport 20 U/Injection Site. Deaths are reported as 0 in each group.

For other adverse events, the record reports 3 of 4 participants affected in the placebo group, 3 of 3 in the Dysport 2.5 U/Injection Site group, 4 of 5 in the Dysport 10 U/Injection Site group, and 4 of 4 in the Dysport 20 U/Injection Site group. These are counts of participants affected, not a description of the number, duration, or severity of every event. A participant may have experienced more than one event; the record does not provide enough detail to describe event totals or overlap.

The registry also lists “Pancreatogenous diabetes” at 33.3% among the top serious terms, but does not report enough context in this record to connect that percentage to a particular group or give its underlying count. The small safety-group sizes make the observed counts descriptive. They do not establish comparative risks or causal attribution. The registry does not report inferential safety comparisons in the information summarized.

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

This study addresses a focused statistical question: the time until spontaneous pain scores meet a specified decrease from baseline after a single intradermal dose of Dysport or saline placebo. Its randomized, double-blind, parallel-group design and home NRS recordings define a framework for comparing treatment groups. The registry also describes a crossover lidocaine-saline run-in before the randomized period.

What the registry record does not provide is the primary endpoint’s numerical result. There is no reported group mean, standard deviation, confidence interval, or inferential comparison for time to onset. It is therefore not possible from this record to describe the direction or magnitude of a treatment-group difference, or the precision with which one was estimated. The registry’s statement that descriptive statistical analysis was performed does not substitute for the missing numerical summaries.

The record also does not report numerical results for the listed secondary outcomes. The safety counts provide a limited descriptive account of participants affected by serious and other adverse events, but do not establish that an event was caused by treatment or support a reliable comparison between groups. The listed adverse-event group sizes are small, and the record does not give fuller event-level details or statistical safety comparisons.

In general, a completed study and a registered design do not alone establish what the outcome data show. Interpretation requires the observed results, the analysis population, treatment of missing observations, and the methods used to compare groups. Those details are not reported in the registry record for the primary endpoint. Accordingly, the registry supports a description of the study question and measurement approach, but not a conclusion about the estimated effect or its statistical uncertainty.

13. Why This Trial Matters Statistically

Several features make this trial statistically informative as a design, even though the registry record does not report its numerical primary-outcome results. The study considered three Dysport dose groups and a saline placebo in a randomized, double-blind, parallel-group period. That structure makes dose-specific comparisons part of the study question rather than reducing the investigation to a single active-treatment group against placebo.

The primary endpoint also focuses on timing. Measuring days until a prespecified decrease in spontaneous pain differs from comparing a single pain score at one visit: it depends on repeated observations and a clear event definition. Participants recorded average and worst pain over the preceding 12 hours twice daily, giving the endpoint a home-measurement component. The registry defines onset as a decrease from baseline of two points or more, which makes the threshold explicit.

The Part A crossover run-in is another design element worth distinguishing from the randomized Part B comparison. Participants received both saline and lidocaine in the run-in, one week apart, before Part B. Keeping those stages distinct helps clarify which data belong to the preliminary crossover and which concern randomized dose groups.

The registry also illustrates why design details and outcome reporting are both necessary for statistical interpretation. Enrollment was 16, while the safety groups contain different numbers at risk, and the primary analysis included only participants who reached onset. Without numerical primary results, group-specific analyzed counts, and details of missing-data handling, readers cannot assess the size or precision of a treatment contrast. The study question is clear, but the posted results do not permit a quantitative answer.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main limitation for interpreting the trial from the registry record is the absence of numerical primary-outcome results. Although the endpoint definition, measurement period and descriptive analysis are stated, group-level time-to-onset values and their variability are not reported. No confidence intervals or inferential comparisons are reported for that endpoint.

The planned enrollment was 16, and the safety groups contain only 3 to 5 participants at risk per group. These small group counts mean descriptive observations may be strongly influenced by individual participants. The record does not report a sample-size justification for the trial, so the intended precision or detectable effect cannot be assessed. Planning illustrations based on an observed effect are not a substitute for that justification.

The primary-outcome analysis population included only randomized participants who reached onset. The registry does not report how many participants reached onset, how participants without onset were handled, or how early discontinuation and missing home pain records were addressed. These details matter because the endpoint depends on repeated measurements over time.

The registry does not report the randomization procedure, allocation concealment, masking implementation, multiplicity strategy, or a full statistical analysis plan. It lists secondary outcomes but does not provide their numerical results. Safety reporting includes participant counts, but limited event-level context; the listed serious-event term and percentage lack a clearly reported group context in this record. These limitations constrain interpretation of efficacy estimates, uncertainty, and comparative safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Dysport in Post-Surgical Neuralgia — NCT03663101.
• Registry record last updated 2021-01-12; status last verified 2020-12.
• Results first posted 2020-12-04.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry record describes NCT03663101, “Dysport in Post-Surgical Neuralgia,” a completed Phase 2 randomized, double-blind, parallel-group study sponsored by Ipsen. It lists enrollment of 16, a study start date of 2018-10-30 and primary completion on 2019-11-08. The condition was chronic scar pain.

Part A used a saline-lidocaine crossover run-in; Part B compared three single-dose intradermal Dysport doses with saline placebo. The primary endpoint was time to a decrease of two points or more from baseline in spontaneous NRS, measured in days through Week 16 or early discontinuation. Only participants who reached onset were analyzed, and the registry says descriptive statistical analysis was performed.

Numerical primary and secondary outcome results are not reported in the registry record. Safety counts are reported by group, with no deaths listed. The record does not report a detailed statistical analysis plan, sample-size justification, or handling of missing primary-outcome observations.