Safety Study of DWP-450 (Botulinum Purified Neurotoxin, Type A) Injection to Treat Glabellar Lines: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety Study of DWP-450 (Botulinum Purified Neurotoxin, Type A) Injection to Treat Glabellar Lines (NCT02184988), a na phase 2 study. The primary outcome is The Safety of Repeat DWP-450 Treatments - Proportion of Subjects With at Least One Adverse Event Over 1 Year.

2. Clinical Question

3. Trial Design

This was a Phase II, multi-center, open-label, multiple-dose, single-group trial of DWP-450 in adults with moderate-to-severe glabellar lines. The registry lists Evolus, Inc. as the sponsor, an enrollment of 352, and a completed study status. The recorded study start is 2014-08, and primary completion is recorded as 2015-12.

All participants were assigned to the DWP-450 intervention; the registry record does not list a separate control arm. Allocation is recorded as NA, and masking as NONE. These design features matter when interpreting safety: the event counts describe what was recorded among participants in the treated group, but there is no concurrent group in this trial against which to compare those counts.

The title and primary endpoint refer to repeat treatment and safety over a 365 Days timeframe. The primary outcome is described as the proportion of subjects with at least one adverse event from Day 0 through Day 365. Details such as the exact dosing schedule, follow-up procedures, event-collection methods, and treatment received by each participant are not reported in the registry record.

The registry lists 2 outcome measures and no analyses. The design information establishes the study’s broad purpose and structure, but does not provide a full statistical analysis plan or an explicit result for the primary endpoint. The safety counts reported in the adverse-event record can be read descriptively, while questions requiring a treatment comparison or a fully specified primary-endpoint estimate cannot be answered from 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

Reasons for not completing this period:

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.

6. Primary Endpoint

The registry lists the primary outcome as The Safety of Repeat DWP-450 Treatments - Proportion of Subjects With at Least One Adverse Event Over 1 Year, measured over 365 Days.

The primary endpoint concerns the proportion of participants with at least one adverse event from Day 0 through Day 365. It is a participant-level binary outcome: each participant either had at least one recorded event during the stated period or did not. Counting participants in this way differs from counting every event, because a participant with multiple events still contributes once to the “at least one” outcome.

This type of endpoint is used to describe how commonly participants experienced an event during a defined observation period. For a safety-focused trial, it provides a direct summary of the number of participants affected, rather than the total burden of repeated events. It does not by itself describe the event’s severity, duration, cause, or relationship to treatment; those questions require additional definitions and results.

The registry record states the endpoint definition and timeframe, but does not report the primary endpoint’s event count or proportion. The adverse-event record lists 141 participants under other adverse events, but the registry does not explicitly identify that figure as the primary endpoint result. It should therefore not be substituted for the stated primary proportion. The serious adverse-event count is reported separately.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The stated primary endpoint is a binary participant-level outcome: at least one adverse event during the period from Day 0 through Day 365. In general, a binary endpoint classifies each participant into one of two outcome states. The participant is counted once for the “at least one event” outcome even if multiple events occurred. This makes the endpoint a measure of how many participants were affected, not a measure of the total number of events or how often events recurred.

In general, a proportion is calculated by dividing the number of participants meeting the outcome definition by the number of participants assessed for that outcome. Interpreting such a result requires knowing both the event count and the applicable denominator, as well as how missing follow-up is handled. The registry record gives the primary endpoint definition but does not report its explicit event count or proportion, and it does not describe missing-data handling for that endpoint.

The adverse-event listing separately reports 352 participants at risk and 7 affected by serious adverse events, and 352 at risk and 141 affected by other adverse events. These counts are not automatically interchangeable with the primary endpoint result. The primary endpoint is defined as at least one adverse event over the stated period, while the adverse-event record separates serious and other categories. The registry record does not explicitly say that the other-event count is the primary endpoint count, or clarify how participants appearing in more than one category are handled.

In general, confidence intervals express uncertainty around an estimated effect or proportion. A narrower interval indicates greater statistical precision, while a wider interval indicates less precision. The registry record does not report a confidence interval for the primary endpoint or the adverse-event counts. Without an explicit estimate and uncertainty interval, the precision of the primary safety estimate cannot be assessed from the registry record.

In general, a comparison between groups can help distinguish differences associated with an intervention from background event occurrence, provided the study design and analysis support that comparison. This trial is listed as single-group, with no masking and no randomized allocation, and no comparator is described. Its event counts therefore summarize observations in the treated group; they do not estimate a contrast with an untreated or alternative-treatment group. No adjustment for differences between groups is relevant to a comparison that is not present in the listed design.

The registry lists no analyses. It does not report a statistical analysis plan, the analysis population for the primary endpoint, or an account of how participants with incomplete follow-up were handled. In general, the analysis population matters because a result can change depending on who is included and what outcome information is available. The record’s “at risk” counts describe the denominators shown in the adverse-event listing, but do not answer all questions about the primary endpoint population.

Sample-size planning is also distinct from interpreting observed results. The stated planning assumptions describe an illustration using two-sided significance level 0.05, equal allocation between two arms, and a normal approximation, with an effect to detect defined as a fraction of an observed effect. Those assumptions describe a planning illustration, not the listed single-group trial design. The registry record does not report a trial-specific sample-size justification. Such planning values are not observed power, and they do not supply a missing primary endpoint estimate.

In general, over-dispersion matters when observed variability is greater than a model’s assumptions allow. It can make standard errors too small if ignored. This endpoint is a participant-level binary outcome, and no dispersion estimate or model-based analysis is reported in the registry record. The record therefore does not support a more detailed assessment of model fit, over-dispersion, or alternative analytic methods.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Botulinum Neurotoxin, Type A")
n      <- c(352)
events <- c(148)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Botulinum Neurotoxin, Type A  352  148  42.0  36.8  47.4  37.0  47.3  37.0  47.3

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures, but does not report the full set of outcome definitions or an analysis plan that would show how multiple outcomes were handled. It also lists no analyses. The record therefore does not say whether inferential tests were planned, whether any adjustment for multiple testing was intended, or how the primary endpoint was prioritized in analysis beyond its designation as primary.

Multiple-dose treatment is part of the study description, but that does not establish that dose groups were compared or that statistical tests were conducted across dosing schedules. The registry record does not describe dose-level groups or a multiplicity strategy. It would be inappropriate to infer an analysis plan from the phrase “multiple dose.”

Missing-data handling for the primary endpoint is not reported in the registry record. The record does not explain whether all enrolled participants completed follow-up through Day 365, how participants with incomplete observation were treated, or whether any imputation or sensitivity analysis was used. These details matter because a participant’s status may be unknown if event follow-up is incomplete.

The registry record also does not identify the analysis population used for the primary outcome. The adverse-event listing provides at-risk counts, but those counts do not establish how the primary endpoint analysis population was defined. No information is reported about exclusions, protocol deviations, or the handling of participants who did not receive all planned treatments.

12. 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: basal cell carcinoma (0.6%), device failure - failure of pacemaker/defibrillator (0.3%), pancreatitis (0.3%), breast cancer (0.3%), malignant anorectal neoplasm (0.3%).

The adverse-event listing reports 7 participants affected by serious adverse events among 352 at risk, and 141 participants affected by other adverse events among 352 at risk. The registry record also lists 0 deaths. These figures are descriptive counts, not a comparison with another group, and the record does not provide confidence intervals for them.

The serious-event terms listed include Basal cell carcinoma (0.6%), Device failure - failure of pacemaker/defibrillator (0.3%), Pancreatitis (0.3%), Breast cancer (0.3%), Malignant anorectal neoplasm (0.3%), and Dysfunctional uterine bleeding (0.3%). The record does not explain whether these terms are mutually exclusive, whether participants could appear under more than one term, or whether each event was considered related to treatment. They should not be added together or interpreted as a causal assessment.

In general, serious-event counts describe events meeting a seriousness definition; they do not alone establish cause or treatment effect. The registry record does not report event-level assessments of causality, duration, or outcome for these terms.

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

The registry record describes safety observations in a Phase II, open-label, single-group study of DWP-450 in adults with moderate-to-severe glabellar lines. It reports the primary safety question and separate adverse-event counts, including 7 participants affected by serious events and 141 affected by other events among 352 at risk in each listing. It also records 0 deaths.

These figures do not establish whether DWP-450 caused an event. Without a comparator group, the study does not show how the observed counts differ from what would have occurred under another treatment or without treatment. Open-label conduct also means masking cannot be assumed for event assessment. The registry does not report whether events were judged related to treatment.

The primary endpoint is the proportion of participants with at least one adverse event during Day 0 through Day 365, but the registry record does not provide an explicit result for that proportion. The other-event count should not be treated as that result unless the record establishes the categories and endpoint are equivalent. No confidence interval or analysis result is listed, so the precision of the primary endpoint is not available.

The findings are therefore a descriptive safety record, not a definitive causal comparison. They do not establish that treatment is safe or unsafe, and they do not provide advice for an individual’s care. Interpretation is limited to the outcomes and follow-up information recorded in the registry; additional details about event definitions, follow-up completeness, and analysis methods are not reported in the registry record.

14. Why This Trial Matters Statistically

This trial illustrates a central statistical distinction: an event count in a treated group is not the same as an estimate of treatment effect. A single-group design can describe events observed during follow-up, but it cannot provide a direct comparison with another group. That distinction is especially important for safety outcomes, where some events may occur regardless of the intervention.

The endpoint also highlights why definitions matter. The primary outcome concerns participants with at least one adverse event over a specified period, while the registry’s adverse-event listing separates serious and other events. Unless the relationship between those records is explicit, a count from one category should not be assumed to be the primary endpoint result. Clear outcome reporting is necessary for readers to know which participants and events contribute to an estimate.

Precision is another important consideration. Counts without an uncertainty estimate do not show how precisely the underlying event frequency has been estimated. The registry record does not report a confidence interval for the primary endpoint. Nor does it provide a comparator-based analysis that could support a relative safety estimate.

Finally, the record distinguishes trial design from planning assumptions. A two-arm planning illustration does not turn a single-group study into a comparative trial, and it does not establish the study’s original sample-size rationale. These distinctions help keep descriptive safety findings, statistical planning, and causal conclusions separate.

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 principal limitation for interpretation is the single-group design. With no comparator, the adverse-event counts cannot show whether event occurrence was higher or lower than it would have been under another treatment or without treatment. The open-label design also means the registry does not describe blinded event assessment.

The primary endpoint is defined, but its explicit result is not reported in the registry record. The adverse-event listing provides separate serious and other-event counts, but the record does not state whether the other-event count corresponds to the primary endpoint. It also does not report confidence intervals or other uncertainty estimates for the primary outcome.

Important operational details are not reported in the registry record, including the exact dosing schedule, event-collection procedures, completion of follow-up through Day 365, missing-data handling, and the primary endpoint analysis population. The relationship of individual events to treatment is not reported, nor are event durations or outcomes. The record lists 2 outcome measures and no analyses, and does not give a statistical analysis plan or a trial-specific sample-size justification.

These limitations restrict the findings to a descriptive reading of the recorded safety counts. They do not support a comparative estimate, a causal conclusion, or a complete assessment of the precision of the primary safety endpoint.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety Study of DWP-450 (Botulinum Purified Neurotoxin, Type A) Injection to Treat Glabellar Lines — NCT02184988.
• Registry record last updated 2019-04-24; status last verified 2019-04.
• Results first posted 2019-02-05.
• 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.

19. Record Summary

NCT02184988 is a completed Phase II, multi-center, open-label, multiple-dose, single-group study sponsored by Evolus, Inc. It enrolled 352 adults for DWP-450 treatment of moderate-to-severe glabellar lines. The recorded start is 2014-08, and primary completion is 2015-12.

The primary endpoint was the proportion of participants with at least one adverse event from Day 0 through Day 365. The registry record lists 2 outcome measures and no analyses, but does not report an explicit primary endpoint result. Its adverse-event listing reports 7 participants with serious adverse events and 141 with other adverse events among 352 at risk in each category, and lists 0 deaths. The single-group design supports descriptive interpretation, not a direct treatment comparison.