The Effects of Fractional CO2 Laser on Poikiloderma of Civatte: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effects of Fractional CO2 Laser on Poikiloderma of Civatte (NCT04581330), a randomized na study. The primary outcome is Change in Overall Improvement of Poikiloderma of Civatte (POC) From Baseline at 12 Weeks.

2. Clinical Question

The study asks whether fractional CO2 laser treatment is associated with improvement in Poikiloderma of Civatte (POC), as judged from photographs by dermatologists blinded to treatment details. The registry describes treatment of one half of each subject’s neck and no laser treatment on the other half. The primary assessment is at 12 weeks after treatment. The record also lists patient satisfaction at 12 and 24 weeks and procedure-related adverse events as secondary outcomes.

The registry’s study description presents safety and efficacy as aims, but it does not post a primary outcome estimate or a comparison between treated and untreated sides. Therefore, the clinical question can be described from the planned outcome and arm descriptions, but the posted record does not establish the degree of improvement, its precision, or whether ratings differed by treatment side.

3. Trial Design

The registry lists the study as randomized, with single masking and a single-group model. It also describes a within-subject arrangement: one half of each subject’s neck was assigned laser treatment, while the other half was untreated. The registry does not explain how its single-group model designation relates to the treated and untreated sides, nor does it describe the unit or procedure used for randomization. These details should not be inferred from the labels alone.

Enrollment is listed as 10. The study status is completed. The recorded start date is 2021-04-01, and primary completion is listed as 2021-12-15. The intervention is a device, identified as the DEKA SmartXide C02 laser. The registry describes the primary assessment as a blinded review by dermatologists who are unaware of treatment parameters and treatment laterality at each photograph time point. Reviewers were to identify baseline and post-treatment images from randomized, paired images for all subjects.

The primary outcome is change in overall POC improvement from baseline at 12 weeks. Secondary outcomes listed are patient satisfaction at 12 weeks, patient satisfaction at 24 weeks, and the number of participants with at least one procedure-related adverse event. The record lists 5 outcome measures but contains 0 analysis entries. The primary outcome information is not reduced to a single comparison because it has several categories or time points, as noted in the registry.

The record does not report the detailed randomization method, the masking procedures beyond the single-masking designation and blinded photographic assessment, or the allocation sequence. It also does not report a protocol-level statistical analysis plan or the rationale for the enrollment target. The study’s registry design labels and arm descriptions can be stated, but they do not resolve these missing design details.

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: The Control Arm assignment consists of the same participants from the intervention arm, but the only difference is that the other half of the participant's neck was considered as the Control which was not treated with the ablative fractional CO2 laser.

Overall Study

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: The Control Arm assignment consists of the same participants from the intervention arm, but the only difference is that the other half of the participant's neck was considered as the Control which was not treated with the ablative fractional CO2 laser.

6. Primary Endpoint

The registry lists the primary outcome as Change in Overall Improvement of Poikiloderma of Civatte (POC) From Baseline at 12 Weeks, measured over Baseline, 12 weeks.

The primary endpoint is described as change in overall improvement of Poikiloderma of Civatte from baseline at 12 weeks. The outcome is expressed as a percentage and assessed with the Physician’s Global Aesthetic Improvement Scale. The scale ranges from 0% for no improvement to 100% for complete clearance, with reviewers rating improvement in 10% increments.

Photographs are central to this assessment. Dermatologists on an independent panel were to receive randomized, paired images and identify baseline and post-treatment images for each subject. The description states that reviewers would be blinded to treatment parameters and to which side was treated at each photograph time point. Blinded image review is intended to reduce the influence of expectations about which treatment area should look better. It does not, by itself, ensure that ratings are free of measurement error or that all reviewers would give the same score.

A global improvement scale is used to capture an overall visual judgment rather than a single physical measurement. That makes the endpoint relevant to the study’s stated goal of assessing visible POC improvement, while also making interpretation dependent on how reviewers apply the scale. The registry does not report whether reviewer agreement was assessed, how ratings were combined across dermatologists, or how the endpoint was summarized across participants.

Most importantly, the record does not report the observed endpoint values or a treatment-side comparison. The scale and assessment procedure are described, but the posted information does not show the amount of improvement at 12 weeks or the precision of an estimated effect.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help distinguish what the registry specifies from what is available for interpretation. The explanations below are general; they describe how these methods and reporting elements are usually understood, not additional procedures confirmed for this study.

What a treatment contrast means

A treatment contrast is a comparison of outcomes under the intervention with outcomes under a comparator. In this study’s arm descriptions, one side of the neck receives fractional CO2 laser and the other side is untreated. A paired or within-subject comparison can account for some features shared by both sides of the same person, because those shared features need not be estimated as if they differed between separate participants. But a valid statistical analysis still has to respect how treatment was assigned and how outcome ratings were collected. The registry does not report the actual comparison estimate or enough analysis detail to establish exactly how those features were handled.

Randomization is intended to reduce systematic differences in assigned treatment groups or areas. The registry labels allocation as randomized, but does not describe the sequence generation, concealment, or operational details. The single-group model designation also sits alongside descriptions of treated and untreated neck halves. The record does not explain how those labels fit together. Therefore, the randomization label can be reported, but the specific protections against allocation bias cannot be assessed from the registry information.

How to understand a continuous outcome

The primary measure is a percentage rating of improvement, summarized in the record as a mean with standard deviation. A mean describes the average rating across observations included in a calculation. A standard deviation describes how spread out those observations are around their mean. Neither statistic is reported for the primary outcome in the registry record, so the actual average and variability cannot be interpreted.

General statistical interpretation depends on both the estimated effect and its uncertainty. A confidence interval gives a range of values compatible with the data under the method used and conveys estimation precision. A narrow interval generally indicates more precise estimation than a wide interval, while neither width nor position should be interpreted without knowing what quantity was estimated. No confidence interval or other measure of uncertainty for the primary comparison is reported. A p-value, if reported, would address compatibility with a specified null model under assumptions; it would not by itself describe the size or clinical importance of an effect. No primary comparison p-value is reported.

Why the scale and ratings matter

The Physician’s Global Aesthetic Improvement Scale uses ordered increments from no improvement to complete clearance. Although the registry describes the primary outcome as a percentage and specifies a mean summary, rating scales require careful interpretation: the numerical spacing between response levels may not represent equal changes in the underlying visual condition. The registry does not state whether alternative summaries or sensitivity analyses were planned. Blinded review may help limit expectation-related bias, but the record does not report reviewer agreement, rating variability, or how ratings from the independent panel were combined.

Photographic outcome assessment also depends on image comparability, the selection and pairing of images, and consistent review conditions. The registry says images were randomized and paired and that reviewers were blinded to treatment parameters and laterality. It does not report additional image standardization procedures or whether image quality led to exclusions. These omissions do not show that such procedures were absent; they mean their details are not reported in the registry record.

Over-dispersion and model choice

General: over-dispersion occurs when observed variability is greater than a statistical model expects. When present, standard errors based on an overly restrictive model can be too small, which can make uncertainty appear lower than it is. The appropriate model depends on the outcome scale, the paired or clustered structure, and the observed distribution. The registry does not report an analysis model, estimates of variability, or diagnostics, so it is not possible to determine whether over-dispersion was relevant or how it was addressed in this study.

For a within-person design, observations from the two sides of the same participant are not ordinarily treated as independent in a comparison. Likewise, ratings from multiple reviewers of the same images may be related. A statistical analysis should account for dependence when it is present. The record does not specify whether the unit of analysis was the participant, side, image, or reviewer rating, and it does not state how those sources of dependence were handled. No particular model should therefore be attributed to the study.

Planning illustrations are not trial findings

The registry includes a description of sample-size illustrations based on a fraction of an observed effect. It states that the illustrations use a two-sided significance level of 0.05, equal allocation, and a normal approximation; for non-time-to-event outcomes they are framed as participants per arm. The description explicitly distinguishes these illustrations from the trial’s own design. No numerical illustration values are reported in the registry record. Such calculations are planning aids, not observed power and not a substitute for the trial’s actual effect estimate and uncertainty. They should not be used to infer a design justification or to retrofit a conclusion to the observed study.

Overall, the registry provides outcome definitions and some design labels, but does not report the numerical primary result, the inferential analysis, or enough methodological detail to independently assess the treatment estimate. General statistical concepts can explain what those missing elements would contribute, but cannot fill in the unreported analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 5 outcome measures and 0 analysis entries. The primary outcome description refers to several categories or time points and is not reduced to one comparison in the posted outcome information. This matters because a study can generate multiple possible comparisons across outcomes, time points, categories, or ratings. General: when many comparisons are considered, the chance of at least one apparently notable result can increase unless the analysis plan specifies how multiplicity will be addressed. The registry record does not report a multiplicity strategy, a hierarchy of outcomes, or which comparisons were intended to be confirmatory.

The listed secondary outcomes are patient satisfaction at 12 weeks, patient satisfaction at 24 weeks, and the number of participants with at least one procedure-related adverse event. The record does not report numerical results for those outcomes. It also does not state whether the secondary outcomes were analyzed separately, whether any adjustment for multiple testing was planned, or how the several primary outcome categories or time points were to be combined.

Missing-data handling is not reported in the registry record. The record does not state how missing photographs, unavailable follow-up ratings, incomplete satisfaction assessments, or withdrawals would be handled. It does not identify an analysis population, such as all randomized participants or only participants with evaluable images, nor does it report whether any participants were excluded from an outcome analysis. These details affect the interpretation of an estimate because the observed participants and observations may differ from those initially enrolled or assigned.

The registry does not report an intention-to-treat approach, a per-protocol analysis, imputation, or sensitivity analyses. That absence should not be taken as proof that no such procedures were conducted; their use is not reported in the registry record. With no analysis entries and no primary comparison estimate, readers cannot determine how multiplicity, missing observations, or analysis populations influenced the posted results.

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.

The serious adverse event figures list 10 participants at risk in the DEKA SmartXide C02 Laser group and 10 at risk in the Control group. The number reported as affected by a serious adverse event is 0 in each group. The figures for other adverse events also list 10 at risk and 0 affected in each group. Deaths are listed as 0 in both groups.

These are counts as recorded in the registry, not a complete characterization of the safety experience. The record does not provide event descriptions, severity details beyond the serious-versus-other categories, timing, or a narrative of how events were collected. It also does not report a statistical comparison of adverse events. The registry’s group descriptions concern the treated and untreated sides of the neck, while the at-risk counts are recorded at group level; the record does not explain the counting or analysis unit in further detail.

A count of 0 reported events is not the same as proof that the intervention has no risk. It means no affected participants are listed for these categories in the posted record. The record does not state the completeness of follow-up for safety reporting or whether all participants contributed information throughout the relevant observation period. The figures should therefore be read as the reported counts, not as a definitive estimate of safety or a comparison establishing a difference between treatment conditions.

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

The record establishes that a study was registered to assess fractional CO2 laser treatment for Poikiloderma of Civatte, with an untreated neck area as comparator and blinded dermatologist review planned at 12 weeks. It defines the primary scale and identifies satisfaction and procedure-related adverse events as secondary outcomes. These details explain what the investigators intended to assess.

The record does not report the numerical primary outcome results. It therefore does not show how much improvement was rated, how ratings varied, or whether treated and untreated areas differed. It also does not report uncertainty around a primary comparison. The absence of those estimates is not evidence that the treatment had no effect, nor is it evidence that an effect was present. The posted registry information is insufficient to quantify the primary outcome.

Enrollment of 10 is a description of study size, not a result. Without the outcome data and analysis, it cannot show whether the estimate was precise, whether ratings were consistent, or whether incomplete observations influenced the findings. The planning illustration description is not a report of the trial’s power or its design justification. Any sample-size illustrations are planning calculations rather than observed study results.

The adverse event record lists 0 serious and 0 other adverse events affecting participants in each group, and 0 deaths in each group. Those counts describe the registry entries; they do not establish absence of risk. The record does not provide enough detail to judge event ascertainment, follow-up completeness, or the context of any safety monitoring.

Thus, the registry supports a description of the study question, design labels, outcome definitions, and posted safety counts. It does not support a numerical conclusion about the primary treatment contrast or the precision of that contrast. A reader should distinguish this lack of posted efficacy results from a negative efficacy finding.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it describes a within-subject treatment arrangement: laser treatment on one half of the neck and no treatment on the other half. In general, paired designs can make a comparison less sensitive to characteristics shared by both areas of the same participant. At the same time, paired observations require analysis methods that preserve the relationship between sides. The registry does not report the analysis model or clarify how the single-group model label relates to the treated and untreated sides, so the intended design structure cannot be fully evaluated from the record.

The primary outcome also relies on blinded visual ratings rather than a direct physical measurement. The registry describes randomized paired photographs and independent dermatologist assessment, which identifies an effort to reduce awareness of treatment laterality. Such an approach raises statistical questions about rating variability, reviewer agreement, and how multiple ratings are combined. Those details are not reported, and the outcome result itself is not posted.

The record is also a useful example of why outcome definitions and outcome results are distinct. A scale, time point, and reviewer procedure explain how an outcome was meant to be assessed, but they do not tell readers what the study found or how certain the estimate is. Here, the registry provides outcome definitions but no analysis entries or primary estimate. This limits quantitative interpretation even though the study is marked completed.

Finally, the study’s design labels, arm descriptions, and safety counts require careful reading together. The record labels allocation randomized and the model single group, while describing treated and untreated halves. It reports no adverse events in either recorded group, but no event detail or inferential safety comparison. Keeping these distinctions clear prevents design labels or zero counts from being mistaken for a complete statistical result.

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 of the registry information is that it does not report the primary outcome estimate or a treatment comparison. The primary endpoint is described, but no numerical result, variability estimate, or measure of uncertainty is posted. This prevents assessment of effect magnitude, precision, and the extent to which ratings might vary among participants or reviewers.

The design description contains labels that are not fully reconciled: allocation is listed as randomized and the model as single group, while the arm descriptions specify treatment of one neck half and no treatment of the other. The registry does not explain the randomization unit, the assignment procedure, or how the labels correspond to the split-neck comparison. It also does not describe the statistical unit or model used for analysis.

The outcome depends on photographic assessment with a global rating scale. Although the record describes blinded reviewers and randomized paired images, it does not report reviewer agreement, the number of ratings contributing to each result, or the procedure for combining ratings. Details about image standardization, missing photographs, and rating exclusions are not reported in the registry record.

Enrollment is listed as 10, but the record does not provide a trial-specific sample-size justification or explain the planned analysis population. Missing-data procedures, multiplicity handling, and sensitivity analyses are also not reported. The registry lists 5 outcome measures and 0 analysis entries, and the primary outcome is not reduced to one comparison in the posted information.

Safety counts are limited to group-level entries, with no event descriptions or information on ascertainment and follow-up completeness. These limitations concern what the registry record reports; they do not establish that unreported procedures or data were absent from the conduct of the study.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: The Effects of Fractional CO2 Laser on Poikiloderma of Civatte — NCT04581330.
• Registry record last updated 2023-03-07; status last verified 2023-02.
• Results first posted 2023-03-07.
• 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 concerns a completed randomized study of fractional CO2 laser for Poikiloderma of Civatte, with enrollment of 10. It lists single masking and a single-group model, and describes laser treatment on one half of the subject’s neck with the other half untreated. The primary endpoint is a blinded dermatologist assessment of improvement at 12 weeks using the Physician’s Global Aesthetic Improvement Scale.

The record lists patient satisfaction at 12 and 24 weeks and procedure-related adverse events among the secondary outcomes. It contains 0 analysis entries and does not report a numerical primary outcome result or comparison. For both the laser and control groups, 10 participants are listed at risk, with 0 serious adverse events, 0 other adverse events, and 0 deaths reported as affecting participants. Detailed analysis methods, missing-data procedures, and sample-size justification are not reported in the registry record.