Evaluation of Efficacy and Tolerance of Crystal Peel in the Treatment of Adults Presenting Facial Mild Acne: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of Efficacy and Tolerance of Crystal Peel in the Treatment of Adults Presenting Facial Mild Acne (NCT05821296), a na na study. The primary outcome is Comparison of the Change From Baseline of Count Lesions on Each Visit to Evaluate the Efficacy and Clinical Performance of Crystal Peel for the Treatment of Acne..

2. Clinical Question

The registry describes the study as an evaluation of efficacy and clinical performance, as well as tolerance, in adults with mild facial acne. Lesion counting was designated as the primary assessment and was to be performed at every visit using visual observation and palpation. The question is therefore about the pattern of counts over time within a group receiving the peel, not about a randomized contrast between treatments.

Other stated aims include assessments of pores and skin texture, global assessments by the investigator and participant, satisfaction, tolerance and adverse events. Those outcomes may add descriptive context, but they do not substitute for a reported primary-endpoint result. In particular, without a comparator group, changes from baseline alone cannot separate a treatment-associated pattern from changes that might occur over time for other reasons.

3. Trial Design

This is a completed, interventional, single-group study sponsored by Dermosciences France. The registry lists the phase as NA, allocation as NA and masking as none. Enrollment is listed as 42. The study started on 2023-01-23 and had a primary completion date of 2023-06-07. The registry describes it as confirmatory and post market.

All participants were assigned to the Crystal Peel group as described in the registry; there is no separate control arm. The peel was described as 2.5 ml applied in up to 3 coats, on Day 15, Day 36 and Day 57. The lesion-count schedule lists five visits: Visit 1 on Day 0, Visit 2 on Day 15, Visit 3 on Day 36, Visit 4 on Day 57 and Visit 5 on Day 78. Thus, the primary question is framed around changes from baseline over scheduled visits within the study group.

The endpoint description identifies the per-protocol population as participants who used the device at least once and had no major deviation from the clinical investigation plan. The number meeting that definition, and the number contributing data at each visit, are not reported in the registry record. Nor are details reported about the handling of participants who stopped treatment or missed visits.

The registry lists secondary assessments covering investigator and patient global assessment, local and overall tolerance, satisfaction, adverse events, and several pore measures assessed by the Colorface device. It lists 16 outcome measures and 53 analyses, but the registry record does not describe the statistical methods used for those analyses. As a single-group study without masking, it can describe observed changes and tolerability within the enrolled group, but it does not provide a like-for-like controlled treatment comparison.

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 42 enrolled patients, 33 met study eligibility criteria and were included to Crystal Peel treatment and 9 did not met inclusion criteria number 6 (i.e: low number of acne lesions).

Overall Study

Analysis population for the primary outcome, as defined in the registry: Per protocol (PP) population (any patient having used at least once the investigational device and without any major deviation to the clinical investigation plan.

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 Comparison of the Change From Baseline of Count Lesions on Each Visit to Evaluate the Efficacy and Clinical Performance of Crystal Peel for the Treatment of Acne., measured over At each protocol visit (i.e: Visit 1/Day 0, Visit 2/Day15, Visit 3/Day 36, Visit 4/Day 57 and Visit 5/Day 78)..

The primary endpoint is the count of acne lesions at each protocol visit, with change from baseline used to evaluate efficacy and clinical performance. Lesions were to be counted using visual observation and palpation. The defined total comprises inflammatory lesions (papules and pustules), non-inflammatory lesions (whiteheads and blackheads), and other acne lesions (nodules). The facial areas are the front, both cheeks and the chin above the jaw line; the nose is excluded.

Counts are useful for describing how the visible and palpable lesion burden changes over time. Repeating the assessment at scheduled visits can show whether counts follow a consistent pattern during the study period or vary between visits. A baseline comparison also gives each participant a reference point, although the registry record does not report the numerical counts, changes, or uncertainty estimates needed to characterize that pattern.

Lesion count is a quantitative count outcome, not a continuous measurement with an unrestricted range. In general, count data can be unevenly distributed, and repeated observations from one participant are related rather than independent. Appropriate analysis therefore needs to account for the outcome's count structure and the repeated measurements. The registry record does not report which analysis approach was used.

Even a clearly observed within-group change would not by itself establish that the peel caused that change. With no separate comparator group, the endpoint describes change over time in participants receiving Crystal Peel, rather than a treatment effect estimated against a concurrent control.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes repeated lesion counts within one group. It does not report the statistical methods used to analyze those counts. The concepts below explain general considerations relevant to this kind of outcome and design; they are not claims about the methods actually used in the study.

Why does the count outcome matter?

A lesion count is a non-negative integer measurement. In general, count outcomes are often analyzed with methods designed for counts, rather than methods that assume a continuous outcome with normally distributed errors. The choice depends on how counts are distributed and on the study question. A model may describe a mean count, a change in count, or a relative change, but the registry record does not report which quantity was estimated.

Count data can show more variability than a simple count model expects. This is called over-dispersion: observations vary more widely than the model's assumed distribution allows. In general, ignoring over-dispersion can make uncertainty estimates too small and confidence intervals too narrow. Researchers may use a model that allows extra variability or another appropriate method, but the registry record does not state whether over-dispersion was assessed or how it was handled.

How should repeated visits be handled?

Each participant was scheduled for lesion counts at baseline and later protocol visits. In general, measurements from the same person tend to be related. An analysis that treats every visit as independent may misrepresent the amount of information in the data. Repeated-measures methods can account for within-participant association and estimate the pattern over time. The registry record does not specify whether such a method was used, how visit was represented, or whether the analysis used all scheduled visits jointly.

The primary outcome description refers to change from baseline at each visit. In general, an analysis can estimate a separate baseline contrast for each follow-up visit or model the entire trajectory. Those approaches answer related but not identical questions and may produce different estimates and uncertainty. The record does not identify the exact estimand, model, contrast or reporting scale.

What does a confidence interval convey?

In general, a confidence interval gives a range of values compatible with the data and the assumptions of the analysis, and it communicates precision as well as direction. A narrow interval indicates greater statistical precision than a wide interval, but neither width nor statistical significance alone determines whether a difference matters clinically. No confidence interval for the primary outcome is reported in the registry record, so its precision cannot be evaluated.

A p-value, when reported, summarizes how incompatible the data are with a specified null hypothesis under the model assumptions. It does not give the probability that the null hypothesis is true, and it does not measure clinical importance. The registry record does not report a primary-endpoint p-value or enough analytic detail to interpret one.

What can a baseline comparison establish?

In general, a within-group comparison describes change relative to a starting measurement. It is not equivalent to a treatment-versus-control contrast. Without a concurrent comparison group, other time-related influences cannot be separated from the change associated with receiving the intervention. This limitation is about the design, not about a particular statistical model.

Use of a per-protocol population can also affect interpretation. This study defines that population by use of the device at least once and absence of a major deviation from the clinical investigation plan. In general, excluding participants based on adherence or protocol deviations can create differences between those analyzed and those enrolled. The registry record does not report the analysis-population size or the reasons and counts for exclusions.

What do planning calculations mean?

Sample-size calculations are planning illustrations, not results from the enrolled study and not observed power. The stated planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation and an effect defined as a fraction of the observed effect. The assumptions also distinguish participants per arm for non-time-to-event outcomes from total events for time-to-event outcomes.

Those assumptions do not describe this single-group study's design: the registry lists no randomized comparison or two-arm allocation. The record does not report the trial's own sample-size justification. Any planning illustration based on an observed effect should not be confused with the study's enrollment or evidence that the study had a particular probability of finding a result. Numerical planning outputs are not reported in the registry record.

In short, sound interpretation would require the actual endpoint estimates, uncertainty measures, analysis population details and statistical methods. The registry record does not report these for the primary endpoint. General methods for count and repeated-measures data explain what analysts may consider, but cannot recover unreported results or establish which method was applied.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 16 outcome measures and 53 analyses, including the primary lesion-count endpoint and secondary clinical, tolerance, satisfaction, adverse-event and pore assessments. Testing or estimating many outcomes can raise a multiplicity issue: in general, the chance of at least one apparently notable result can increase when many hypotheses are examined. An analysis plan may define a primary outcome, specify which comparisons are confirmatory, or adjust inference for multiple testing. The registry record does not report a multiplicity strategy, hierarchy among secondary outcomes, or the statistical plan. The number of listed analyses alone does not establish how they were conducted or interpreted.

Missing data are also important for repeated visits. Participants may have no recorded count at a visit or may leave the study before the final assessment. The registry record does not report visit-level completeness, reasons for missing observations, or methods for handling missing data. In general, complete-case analysis, imputation and repeated-measures models rely on different assumptions; the appropriate interpretation depends on the missingness process and analysis details. No specific approach can be attributed to this study from the available record.

The stated primary analysis population is per protocol: participants who used the investigational device at least once and had no major deviation from the clinical investigation plan. The record does not report how many met this definition, how deviations were classified, or whether a broader analysis population was also used. It also does not report how the analysis population relates to the safety population. These omissions limit assessment of exclusions, missingness and the robustness of the findings. Numerical efficacy findings and supporting analysis details are 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 0% reporting threshold.

Most frequent non-serious adverse event terms

The safety summary lists 33 people at risk for serious adverse events, with 0 affected, and 33 at risk for other adverse events, with 33 affected. The deaths entry is 0. These are the registry's reported affected-person counts for the Crystal Peel group. The record does not list serious adverse-event terms.

The figures should be read according to the categories reported. In particular, the count of people affected by other adverse events is not necessarily the count of event episodes: one person may experience more than one event, and the registry record does not provide episode counts or descriptions. It also does not state the timing, severity, duration, outcome or attribution of the other adverse events. Therefore, the figures alone cannot establish how the events were characterized or whether they were considered related to the peel.

The safety risk group is listed as 33, while enrollment is listed as 42. The registry record does not explain the difference between those figures, so the reason should not be inferred. The adverse-event entries do not provide a controlled comparison, and they should not be read as a comparative safety estimate. The registry record does not report additional detail needed to interpret the nature or clinical importance of the events.

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

This record documents a completed evaluation of Crystal Peel in adults with mild facial acne, with repeated lesion counts as the primary measure and additional assessments of global impressions, tolerance, satisfaction, adverse events and pores. It identifies the schedule, treatment description and per-protocol definition. The safety summary also reports affected-person counts for serious and other adverse events.

It does not report numerical primary-endpoint results. As a result, the direction and magnitude of change in lesion counts, the variability of those counts and the precision of any estimate cannot be assessed from the registry record. Numerical secondary-outcome findings and detailed safety descriptions are also not reported there.

The study has a single group and no separate comparator. General statistical interpretation of a before-and-after pattern must therefore remain descriptive: even if counts changed, the design alone cannot show how much of the change was caused by the intervention rather than by other influences over time. The absence of masking also matters for outcomes involving observation and judgment, though the record does not report whether assessor procedures addressed that concern.

These limits do not mean the study found no change or that no useful information was collected. They mean that the registry record does not provide the numerical results and methods needed to judge the primary endpoint or the strength of any inference. Likewise, the safety figures are limited to the reported summary categories and do not reveal event details or comparative risk.

The clearest interpretation is therefore about what the study set out to assess and how it was structured, rather than a conclusion about efficacy. Any claim about the size, certainty or cause of a change would require results and analysis details that are not reported in the registry record.

13. Why This Trial Matters Statistically

This study is statistically informative as an example of a common design question: what can repeated measurements before and after an intervention tell us when there is no concurrent control group? The lesion-count schedule provides a way to describe change over time in the treated group, but the design does not isolate the intervention's contribution from other influences on change. That distinction is essential when reading uncontrolled studies.

The primary outcome is a count assessed repeatedly through visual observation and palpation. This raises general analytical considerations about count distributions, variability and within-person correlation. Appropriate methods should reflect the outcome's scale and the fact that observations from the same participant are related. The registry record does not report which methods were used, making this a reminder that an endpoint description and visit schedule are not substitutes for an analysis plan and results.

Population definitions also matter. A per-protocol population based on device use and absence of major deviation can differ from the enrolled group. Without counts of participants analyzed at each visit or information about exclusions and missing data, readers cannot evaluate how much the analysis represents the enrolled participants or how sensitive it may be to attrition.

Finally, the registry lists a broad set of secondary outcomes and analyses. When many outcomes are considered, a prespecified hierarchy and transparent multiplicity approach help readers distinguish confirmatory questions from exploratory findings. Those details are not reported in the registry record. The study therefore illustrates why interpretation depends not only on what was measured, but also on comparison groups, analysis choices, data completeness and transparent reporting of estimates and uncertainty.

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 most consequential limitation in the registry record is the absence of numerical primary-endpoint results. Lesion counts and changes from baseline are not reported, so their magnitude, direction, variability and precision cannot be evaluated. The statistical methods used for the primary analysis are also not reported.

The single-group design has no concurrent comparator, and the registry lists no masking. Consequently, within-group change cannot establish a comparative treatment effect, and observational lesion counting may be susceptible to assessment variation. These are design considerations; the record does not establish that a particular bias occurred.

The primary endpoint is defined for a per-protocol population, but the number meeting that definition is not reported. The registry record also does not report participant flow, visit-level missingness, reasons for missing observations, protocol deviations or methods for handling incomplete data. The gap between the listed enrollment and safety risk group is not explained.

Although the registry lists secondary outcomes and analyses, it does not report their numerical findings, analysis methods, multiplicity handling or a statistical analysis plan. The safety summary provides affected-person counts but not event descriptions, severity, timing or attribution; serious adverse-event terms are not listed. These limitations constrain interpretation of both efficacy and safety and prevent a detailed assessment of precision, robustness or clinical importance.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Evaluation of Efficacy and Tolerance of Crystal Peel in the Treatment of Adults Presenting Facial Mild Acne — NCT05821296.
• Registry record last updated 2024-10-15; status last verified 2024-10.
• Results first posted 2024-10-01.
• 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

NCT05821296 is a completed, single-group, unmasked interventional study of Crystal Peel in adults presenting with mild facial acne. The sponsor is Dermosciences France. Enrollment is listed as 42, with a start date of 2023-01-23 and primary completion date of 2023-06-07. The registry describes the study as confirmatory and post market.

The primary outcome is lesion count at each protocol visit, using visual observation and palpation, with change from baseline as the basis for evaluating efficacy and clinical performance. The endpoint covers specified facial areas and includes inflammatory, non-inflammatory and other acne lesions. The record defines a per-protocol population but does not report its size or numerical primary results.

Secondary outcomes include global assessments, tolerance, satisfaction, adverse events and pore assessments. The safety summary reports 0 affected by serious adverse events, 33 affected by other adverse events among 33 at risk, and 0 deaths. Detailed event descriptions and statistical analysis methods are not reported in the registry record.