A Study to Assess the Safety and Local Tolerability of DFD-03 (Tazarotene) Lotion, 0.1% Compared to Tazorac® Cream, 0.1% in the Topical Treatment of Acne Vulgaris: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study to Assess the Safety and Local Tolerability of DFD-03 (Tazarotene) Lotion, 0.1% Compared to Tazorac® Cream, 0.1% in the Topical Treatment of Acne Vulgaris (NCT03341910), a randomized phase 2 study. The primary outcome is Adverse Event Occurences in DFD-03 Lotion Versus Tazorac Cream Groups.

2. Clinical Question

3. Trial Design

This was a randomized, quadruple-masked, parallel-group Phase 2 study with an active-control design. The registry lists an enrollment of 155 and a completed status. The study began on 2017-08-21, and primary completion was recorded as 2018-05-18. These dates describe the trial record; they do not establish the duration of follow-up for every participant.

Four groups appear in the intervention record: DFD-03 Lotion, 0.1%; Tazorac Cream, 0.1%; DFD-03 Vehicle Lotion 0%; and Tazorac Vehicle Cream 0%. The primary endpoint specifically describes treatment-emergent adverse-event frequency in the two active-treatment groups. The registry lists 54 subjects for DFD-03 lotion and 49 for Tazorac cream in the posted outcome data. The vehicle lotion and vehicle cream groups are also reported, with 26 subjects in each.

The schedules differed between the active treatments. DFD-03 lotion was applied twice daily for 1 minute and rinsed off, whereas Tazorac cream was applied once in the evening and left overnight for approximately 12 hours. The vehicle regimens followed the corresponding lotion or cream schedules. This distinction matters when interpreting a comparison: the registry describes two treatment regimens, not simply two products used in an identical manner.

The record identifies randomization and quadruple masking but does not describe the allocation sequence, concealment procedures, or which roles were masked. The method of randomization, stratification factors, and any details of implementation are not reported in the registry record. Nor is the protocol's rationale for the chosen enrollment reported. The listed design features alone cannot establish how well randomization was implemented or how masking was maintained.

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

Analysis population for the primary outcome, as defined in the registry: Safety Population - All subjects who received study product and provided any post baseline safety information.

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: Safety Population - All subjects who received study product and provided any post-baseline safety information.

6. Primary Endpoint

The registry lists the primary outcome as Adverse Event Occurences in DFD-03 Lotion Versus Tazorac Cream Groups, measured over Baseline to Week 12.

The primary endpoint is the frequency count of treatment-emergent adverse-event occurrences from baseline to Week 12. It is a count outcome: the registry states that event frequency was to be compared between the DFD-03 Lotion, 0.1%, and Tazorac Cream, 0.1%, groups. The stated population is the safety population, defined in the record as subjects who received study product and provided any post-baseline safety information.

Counting occurrences can describe the total event burden recorded during a defined observation period. It can also retain repeated events for the same participant, rather than reducing each person's experience to a simple yes-or-no indicator. For that reason, an occurrence count is not interchangeable with the number of participants who experienced at least one event. The registry separately reports counts of participants affected by other adverse events, making this distinction especially important for reading these results.

Adverse-event monitoring is used to characterize safety and tolerability during treatment. The registry also says safety assessments included investigator assessment of local cutaneous tolerance or application-site reactions on the face, vital signs, and adverse events. The primary posted outcome is the frequency count, however; the record does not provide the detailed results of every listed safety assessment. Event severity, duration, relatedness, and specific event categories for this endpoint are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registered endpoint is a count, so its data structure differs from a continuous measurement such as a laboratory value or a binary outcome such as whether a participant experienced any event. For a count endpoint, each qualifying event contributes to the total. One participant may contribute multiple events, and participants may contribute different numbers of events. The posted result gives the number of occurrences by group, but does not describe the individual-level distribution of those counts.

What does a count comparison estimate?

A simple count comparison describes the observed total events in each group. A model-based comparison may instead estimate a contrast in event frequency while accounting for the number of participants or the time participants were observed. The appropriate interpretation depends on the analysis definition and model. The registry states that frequency counts were to be compared, but does not report an analysis method or an inferential estimate for the primary endpoint. Consequently, no model-based effect or uncertainty interval can be interpreted from the posted primary result.

Why can over-dispersion matter?

As a general statistical point, a basic count model may assume that variation in counts follows a particular relationship to the average count. In clinical data, counts can be more variable than that assumption allows, for example when some participants have substantially more events than others. This is called over-dispersion. If present and not handled appropriately, it can make standard errors too small and confidence intervals too narrow. The record does not report a model, a dispersion assessment, or whether repeated events within a participant were considered, so it is not possible to determine how these issues were addressed.

What do confidence intervals and p-values add?

In general, a confidence interval expresses the uncertainty around an estimated effect under the assumptions of the analysis. A p-value evaluates how compatible the observed data are with a specified null hypothesis under a statistical model. Neither is reported for this count endpoint. The occurrence totals alone cannot substitute for either measure, and they do not show whether an observed difference could plausibly reflect sampling variability. A claim of equivalence or non-inferiority would require a prespecified framework and suitable estimates; such information is not reported in the registry record.

What is the distinction between counts and affected participants?

The primary endpoint counts adverse-event occurrences, whereas the adverse-event summary also gives the number of participants affected. These measures answer different questions. A person who experiences several events may contribute several occurrences but only once to an affected-participant count. Conversely, the affected-participant count does not describe the number of events or their distribution. Neither measure alone describes severity, duration, or recurrence patterns in enough detail to reconstruct individual experiences.

What can be inferred from the registered design?

Randomization is intended, as a general design principle, to reduce systematic differences between groups at assignment. Masking can reduce the influence of knowledge of treatment on assessments or reporting. The registry identifies the study as randomized and quadruple-masked, but does not provide enough implementation detail to assess the success of either safeguard. The parallel-group structure means the listed groups received their assigned regimens over the study period; it does not imply that participants crossed between treatments.

The study includes two active treatments and two vehicle groups, but the stated primary endpoint focuses on the active-treatment comparison. A comparison of the active groups should be interpreted in light of their different application schedules: lotion was used twice daily for 1 minute and rinsed off, while cream was used once in the evening and left overnight. The registry does not report whether the primary analysis adjusted for any covariates or accounted for exposure duration.

The record reports no analyses for this endpoint. It also does not report a confidence interval, p-value, adjusted estimate, or detailed statistical plan. General statistical principles can explain what such methods would contribute, but cannot establish which methods were used in this trial. The posted counts are descriptive results and should be kept distinct from a formal inferential conclusion.

10. Multiplicity, Missing Data and Analysis Populations

The registry record does not report a statistical analysis plan for the primary endpoint, including whether the count comparison was prespecified in a detailed protocol or what inferential method was intended. The record lists one outcome measure and no analyses. Although the study includes active and vehicle groups and lists safety assessments beyond adverse-event counts, the available record does not explain how multiple outcomes or comparisons were handled. A multiplicity adjustment, hierarchy of endpoints, or testing strategy is not reported in the registry record.

Missing-data procedures are also not reported in the registry record. The safety population is defined as subjects who received study product and provided any post-baseline safety information, but the record does not say how participants without post-baseline safety information were treated, how incomplete follow-up was handled, or whether event reporting was considered complete through Week 12. The registry outcome counts should therefore be read within the stated safety population, not assumed to represent every randomized participant.

The record does not report whether participants were analyzed according to randomized assignment, treatment received, or another population definition for this endpoint. Nor does it report a method for handling withdrawals, missed assessments, differing exposure periods, or repeated events. These omissions limit assessment of potential bias and the reproducibility of the analysis. They do not establish that a particular procedure was absent from the full study documentation; they mean that the procedure is not reported in the registry record.

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 5% reporting threshold.

Most frequent non-serious adverse event terms

The serious adverse-event summary reports zero affected participants in each of the four groups: DFD-03 Lotion, 0.1%; Tazorac Cream, 0.1%; vehicle lotion; and vehicle cream. The registry also reports the numbers at risk for each group: 54, 49, 26, and 26, respectively. These figures describe what was recorded in the registry during the safety observation period; they do not establish that serious events are impossible or that the treatments have identical safety profiles.

The summary distinguishes serious adverse events from other adverse events. For the active groups, 22 participants in the DFD-03 lotion group and 26 in the Tazorac cream group were affected by other adverse events. The corresponding figures for vehicle lotion and vehicle cream are 9 and 11. These are participant counts, not event-occurrence totals. The primary endpoint's occurrence counts are a separate measure.

The registry lists no top serious-event terms. Details such as event definitions, seriousness criteria, severity, relatedness, timing, and follow-up after treatment are not reported in the registry record. A zero count in a study record is therefore a descriptive result for this trial, not proof of absence of risk.

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

The posted results show adverse-event occurrence counts of 73 for DFD-03 Lotion, 0.1%, and 81 for Tazorac Cream, 0.1%, from baseline to Week 12. They also report the number of participants affected by other adverse events and the number affected by serious adverse events. Together, these figures provide a descriptive view of safety reporting in the trial's registered population and timeframe.

They do not establish that one regimen is safer than the other. The registry does not provide an inferential comparison, an uncertainty interval, or a p-value for the primary count endpoint. Nor does it report whether events were adjusted for observation time or analyzed with a method that accounts for repeated events within a participant. Without those details, the raw occurrence totals cannot support a precise estimate of a comparative effect.

The counts also do not show what kinds of events occurred or how serious or persistent the non-serious events were. A total occurrence count should not be interpreted as a count of affected people. The separate participant figures help clarify that distinction, but do not supply event-level descriptions. The record's zero serious-event participant counts are descriptive and do not prove that either treatment has no serious risks.

The trial was designed around safety and local tolerability, with investigator assessment of facial cutaneous tolerance or application-site reactions, vital signs, and adverse events. The registry summary does not provide detailed results for every assessment. It also does not provide a posted efficacy analysis in the information describing the primary endpoint. The results therefore should be understood as limited safety summaries, rather than a complete assessment of comparative benefit and risk.

Finally, this is a comparison of regimens with different application instructions, not merely a comparison of formulations administered in the same way. The findings apply to the study's stated population, products, schedules, and observation timeframe. Generalizing beyond those conditions requires evidence not reported in the registry record.

13. Why This Trial Matters Statistically

This trial illustrates why the definition of a safety endpoint matters. An adverse-event occurrence count and the number of participants affected by an event are not the same quantity. Reporting both can help readers distinguish the total number of recorded events from how many people experienced any event, but neither measure alone describes event type, severity, recurrence, or duration.

It also illustrates a challenge in comparing count outcomes. Participants can contribute different numbers of events, and repeated events from one person are not necessarily statistically independent. A sound analysis may need to account for variation in event counts and the observation period. The registry reports the occurrence totals but does not report the statistical model or uncertainty around a comparison, leaving the numerical contrast descriptive.

The study's active-treatment regimens differed in their application schedules: the lotion was applied twice daily and rinsed off after 1 minute, while the cream was applied once in the evening and left overnight. That is relevant to interpretation because the study compares regimens as recorded, not products under a common application schedule. The presence of vehicle groups adds context to the design, while the stated primary endpoint concerns the two active groups.

More broadly, the record shows why safety summaries benefit from clear definitions of populations, event counting, analysis methods, missing-data handling, and follow-up. The safety population is defined, and serious and other adverse-event summaries are posted, but several analytic details are not reported. Readers can describe the observed counts while recognizing that the registry does not supply the inferential information needed to quantify precision or make a formal comparative claim.

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 registry gives a brief outcome description but does not provide event-level data or a breakdown by event type, severity, relatedness, or recurrence. The number of adverse-event occurrences therefore cannot show whether the totals reflect many participants with few events or a smaller number of participants with repeated events. The separately posted affected-participant figures do not resolve that detail.

No effect estimate, confidence interval, p-value, or analysis method is reported for the primary count endpoint. The registry does not state whether the analysis accounted for repeated events, differing exposure, or any covariates. It also does not report the missing-data approach or how withdrawals and incomplete safety follow-up were handled. These limitations prevent assessment of the precision and robustness of a formal comparison.

The registry defines the safety population, but does not provide participant characteristics or a detailed account of eligibility beyond mild to moderate facial acne vulgaris. The full randomization and masking procedures are not described. Further detail about the assessment of local cutaneous tolerance, vital signs, and other safety measures is not reported in the registry record.

The listed treatment schedules differed, and the observed results cover the stated baseline-to-Week 12 timeframe. Longer-term safety outcomes are not reported in the registry record. The limitations concern what can be assessed from the registry entry; they do not establish that additional details are absent from other study documentation.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Study to Assess the Safety and Local Tolerability of DFD-03 (Tazarotene) Lotion, 0.1% Compared to Tazorac® Cream, 0.1% in the Topical Treatment of Acne Vulgaris — NCT03341910.
• Registry record last updated 2020-08-17; status last verified 2020-08.
• Results first posted 2020-08-17.
• 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

NCT03341910 is a completed randomized, quadruple-masked, parallel-group Phase 2 study of DFD-03 Lotion, 0.1%, and Tazorac Cream, 0.1%, with vehicle lotion and vehicle cream groups also listed. The registry records enrollment of 155, a start date of 2017-08-21, and primary completion on 2018-05-18. Participants had mild to moderate facial acne vulgaris.

The primary outcome is the frequency count of treatment-emergent adverse-event occurrences from baseline to Week 12 in the safety population. The posted counts are 73 for DFD-03 lotion and 81 for Tazorac cream. The registry separately reports affected-participant counts and no participants affected by serious adverse events in the listed groups. No inferential analysis for the primary count endpoint is reported in the registry record, so the occurrence totals are descriptive rather than a quantified comparative effect.