Excel V 532 nm KTP Laser for Treatment of Erythematotelangiectatic Rosacea & Papulopustular Rosacea: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Excel V 532 nm KTP Laser for Treatment of Erythematotelangiectatic Rosacea & Papulopustular Rosacea (NCT02268474), a na na study. The primary outcome is Degree of Improvement in Erythematotelangiectatic Rosacea and Papulopustular Rosacea.

2. Clinical Question

3. Trial Design

The study is described as prospective, controlled, and split-face, with KTP laser treatment compared with PDL treatment. The brief summary calls it a randomized, controlled split-face study. The official title also uses the terms prospective, randomized, and controlled. However, the registry's allocation field is listed as NA, its model is listed as SINGLE GROUP, and the record flags that it is not a randomized comparison because allocation is NA. These descriptions are not fully consistent. The record therefore does not establish the allocation method for the treatment sides, and a randomized between-treatment comparison should not be assumed from the title alone.

The brief summary describes a single-center study. The registry lists enrollment as 22, while the arm description refers to 20 subjects. The record does not explain the discrepancy or specify how many participants contributed data to the primary outcome analysis. It lists one intervention, named “532nm KTP Laser vs 595nm Pulse Dye Laser,” and describes the study as having two treatment arms. Because the design is split-face, the two treatment conditions may be paired within participants, but the analysis approach for that pairing is not reported.

The listed status is completed. The study start is recorded as 2014-09 and primary completion as 2015-08. The listed follow-up point for the primary outcome is 6 weeks after the final laser treatment. The registry lists no masking for the study, while the primary outcome description says a blinded physician assessed subject photographs. These statements could concern different aspects of masking, but the record does not clarify who was masked or how photograph assessment was conducted. Details of treatment procedures, side allocation, deviations, and participant flow are not reported in 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

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 Degree of Improvement in Erythematotelangiectatic Rosacea and Papulopustular Rosacea, measured over 6 weeks.

The primary endpoint is the degree of improvement in erythematotelangiectatic rosacea and papulopustular rosacea. It is described as a mean score on a scale, with standard deviation, measured at 6 weeks. The score comes from the Physician's Global Assessment Scale applied by a physician assessing subject photographs. Higher scores indicate better improvement. The scale ranges from 0, meaning no improvement, to 4, meaning very significant improvement. The intermediate categories are mild, moderate, and significant improvement, with the registry describing percentage ranges for those categories.

A graded scale can represent ordered clinical judgments in a form that allows a summary across assessments. Using a physician's assessment of photographs also provides a defined assessment source and, according to the endpoint description, a blinded assessor. These features can make the outcome useful for comparing visible improvement under the study's assessment approach. However, a mean score treats the steps of the scale as if their intervals can be summarized numerically. That may be useful for a planned analysis, but the registry does not report the statistical rationale for this summary or whether other summaries were considered.

The endpoint description specifies the assessment method and timeframe, but does not report the observed mean scores, standard deviations, number analyzed, or treatment contrast. Consequently, the record identifies what the primary outcome was intended to measure without showing the degree of improvement observed in either treatment condition or the precision of a comparison between them.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the endpoint summarize?

The primary endpoint is a mean on a physician-rated improvement scale. The scale has ordered categories, from no improvement to very significant improvement, and its higher scores mean better improvement. A mean is a summary of the scores in a treatment condition; a standard deviation describes how spread out those scores are around the mean. These are general explanations of the statistical quantities named in the record. The record does not report the observed means or standard deviations, so neither the average rating nor its variability can be evaluated.

What would a treatment comparison need to show?

A comparison would ordinarily describe how the outcome differs between the KTP and PDL conditions, together with an estimate of uncertainty. A confidence interval is a range of values compatible with the data and the statistical model under its assumptions; it helps show how precisely an effect has been estimated. A p-value, when used, addresses how surprising data at least as extreme as those observed would be under a specified null hypothesis and model. Neither a confidence interval nor a p-value for the primary comparison is reported in the registry record. No treatment-effect estimate is reported either.

These general concepts do not substitute for the missing results. A confidence interval cannot be inferred from the endpoint definition, and a p-value cannot be derived from the scale range. The record also does not identify a statistical model, a planned contrast, or a test for the primary outcome. It lists zero analyses, so the posted record does not document how the endpoint was analyzed.

Why does the split-face design matter?

In a split-face study, treatment conditions are assigned to different sides of the face. If both sides belong to the same participant, their outcome measurements are paired rather than independent. A paired analysis accounts for the fact that measurements from the same person may be more alike than measurements from different people. This is a general design principle, not a description of an analysis documented in this record. The record does not report whether treatment sides were randomized, how the paired data were handled, or whether the final analysis used a paired method.

The record's terminology adds uncertainty: the title and brief summary describe a randomized controlled split-face study, but allocation is listed as NA, the model is SINGLE GROUP, and the record cautions that it is not a randomized comparison. Those entries mean that the randomization and analysis details should not be presumed. In particular, the title alone does not establish that side assignment was random or that the treatment contrast was analyzed as a paired comparison.

What do the planning assumptions mean?

The record describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. The effect to detect is described as a fraction of the observed effect. These are assumptions for a planning calculation, not descriptions of the trial's actual results. The record does not report a numerical observed effect or a numerical planning result in the registry record for interpretation.

In general, a sample-size calculation estimates how many participants per arm would be needed for a specified design and target power under assumed conditions. Such a result is not observed power, does not show that a completed study had adequate power, and does not establish the truth of an effect. Planning figures can change when the target effect, variability, allocation, or analysis assumptions change. The illustrations described in the record should therefore be read only as conditional planning information. The record does not report the study's original sample-size justification or establish that these illustration assumptions were the trial's own design assumptions.

Why can over-dispersion matter?

For count outcomes, over-dispersion means that observed variability exceeds what a chosen model expects. It can make model-based standard errors too small if it is ignored. This is a general statistical issue and is not an outcome feature established for this trial: the primary endpoint is a continuous mean score, and the record does not describe an over-dispersion analysis. More broadly, results depend on whether a statistical model matches the outcome and design. The registry does not document model checks, handling of missing observations, or sensitivity analyses.

There is also no reported analysis population, such as a specification of who was included in the primary analysis, and no account of missing photographs or unevaluable assessments. Without these details, readers cannot judge whether the analyzed observations corresponded to the intended study population or how missing outcome data may have affected an estimate. These are general considerations; the registry record does not describe the choices made for this study.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("532nm KTP Laser", "595nm Pulse Dye Laser")
n   <- c(19, 19)
m   <- c(2.114, 2.088)
sp  <- c(1.5125, 1.681)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  532nm KTP Laser  19  2.114  1.512  1.385  2.843
CARM  595nm Pulse Dye Laser  19  2.088  1.681  1.278  2.898

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and zero analyses. It names the primary outcome but does not report an analysis plan, statistical tests, or results. It also does not report whether additional outcomes or comparisons were assessed outside the registered outcome. As a result, the record does not describe how multiplicity—the issue of interpreting results when multiple outcomes, time points, or comparisons are tested—was addressed. This is not evidence that multiple testing occurred; the approach is simply not reported in the registry record.

Missing-data handling is not reported. The record does not say whether every enrolled participant had an assessable photograph at the 6-week assessment, how missing assessments were treated, or whether any imputation or sensitivity analysis was used. It also does not describe exclusions or protocol deviations that might affect the outcome analysis.

The analysis population is not specified. The listed enrollment is 22, while the arm description refers to 20 subjects, and the record does not reconcile these figures. It does not state how many participants contributed to the primary endpoint or whether analysis included all enrolled participants, only those who completed treatment, or another defined population. Because the design is described as split-face, the record also does not say whether complete paired assessments were required for inclusion.

These omissions limit assessment of the analysis and its susceptibility to bias. They do not establish that data were missing, that the analysis was inappropriate, or that multiplicity affected any result. The relevant methods and outcome results are not reported in the registry record.

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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists serious adverse events for the KTP and PDL groups separately. For the 532nm KTP Laser group, 0 serious events are listed among 22 at risk; for the 595nm Pulse Dye Laser group, 0 serious events are listed among 22 at risk. These are the serious-event figures recorded for the groups. The record also lists 0 deaths in each group.

The separate “other” adverse-event entries list 22 affected among 22 at risk in each group. The record does not provide the event terms or explain what events were included in this category. It lists no top serious-event terms. The categories should not be conflated: the serious-event count is distinct from the other adverse-event count.

These entries describe what the registry reports; they do not establish that no adverse events occurred beyond those captured or entered in the record. The registry does not specify the ascertainment methods, reporting period, event severity details, or how adverse events were attributed to treatment. Because the study is described as split-face, the record also does not clarify how the group-level risk denominators correspond to participants or treatment sides. The safety figures should therefore be read as registry counts, not as a complete account of safety or a comparative estimate of risk.

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

The record establishes that a prospective study was intended to compare a 532nm KTP laser with a 595nm PDL for erythematotelangiectatic rosacea and papulopustular rosacea. It specifies a physician-assessed improvement outcome based on photographs and a 6-week timeframe. Those details tell readers what the study set out to assess and how the primary outcome was defined.

The record does not report the outcome values or the statistical comparison. It therefore cannot show which treatment condition had a higher mean score, whether any difference was statistically distinguishable from chance under an analysis model, or how precise a comparison might be. It also does not establish whether a difference, if observed, would be clinically important. No claim that either treatment works or does not work follows from the absence of posted results.

The design should also be interpreted in light of inconsistent registry descriptions. The title and summary call the study randomized and split-face, but allocation is NA, the model is SINGLE GROUP, and the record warns against treating it as a randomized comparison. The record does not resolve how treatment sides were allocated or how within-participant pairing was handled. Enrollment is listed as 22, while an arm description refers to 20 subjects, with no explanation of the difference or the analysis population.

The safety entries list no serious adverse events and no deaths in either group, alongside other adverse events recorded for all those at risk. These counts are limited by the lack of event terms and further reporting details. The planning assumptions described in the record are not evidence about outcomes, and planning illustrations are not observed power. Overall, the registry provides a study description and endpoint definition, but not enough outcome or methods information to estimate the comparative result.

14. Why This Trial Matters Statistically

This record illustrates why trial titles and summaries should be read alongside design metadata and posted results. The study is described as randomized and split-face in its title and summary, yet the allocation field is NA, the model is SINGLE GROUP, and the record explicitly cautions against interpreting it as a randomized comparison. These differences matter because allocation and analysis structure determine what a treatment contrast can support.

The split-face description makes the unit of analysis especially important. When treatments are compared on different sides of the same participant, the sides are not necessarily independent observations. A valid comparison may need to account for pairing. The registry does not say whether that was done, so readers cannot verify that the analysis matched the stated design. This is a general statistical consideration, not a claim about an analysis that is absent from the record.

The primary outcome is clearly described as a physician-rated scale, but no outcome values or treatment contrast are posted. A well-defined endpoint is useful for understanding what investigators intended to measure; it cannot by itself establish what the study found. Likewise, safety counts and sample-size planning assumptions address different questions from the unreported primary result.

Finally, the difference between the listed enrollment of 22 and the arm description's reference to 20 subjects highlights the importance of distinguishing enrollment from the analysis population. The record does not reconcile the figures. Transparent reporting of participant flow, outcome data, and statistical methods would be needed to assess the comparative evidence. The record is therefore informative about the study question and measurement approach, but limited as a source for estimating treatment effects.

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.

Several record-specific limitations constrain interpretation. The study is described as randomized in its title and brief summary, but allocation is listed as NA and the record cautions that the comparison is not randomized. The model is also listed as SINGLE GROUP despite descriptions of two treatment conditions in a split-face design. The registry does not explain these discrepancies or document how treatment sides were assigned.

The enrollment information is inconsistent: 22 is listed as enrollment, while the arm description refers to 20 subjects. No participant flow or analysis population is reported, so it is unclear how these entries relate to the participants assessed for the primary outcome. The record does not specify whether all participants had complete paired photographs or how missing or unevaluable assessments were handled.

The primary endpoint is defined, but its results are absent. No mean scores, standard deviations, treatment contrast, confidence interval, or p-value are reported. The registry lists zero analyses. It also does not describe the statistical method used, adjustment for the split-face structure, prespecified analysis details, or sensitivity analyses. The masking metadata says none, while the endpoint description refers to a blinded physician; the scope and implementation of that blinding are not clarified.

The outcome is assessed at 6 weeks after the final laser treatment, and no other follow-up result is reported in the record. The safety entries lack event terms and further detail on ascertainment or reporting. These limitations do not establish that the study was conducted improperly or that results were unfavorable. They indicate that the registry record does not contain enough information to evaluate the comparative outcome or its uncertainty.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Excel V 532 nm KTP Laser for Treatment of Erythematotelangiectatic Rosacea & Papulopustular Rosacea — NCT02268474.
• Registry record last updated 2023-02-21; status last verified 2023-01.
• Results first posted 2023-02-21.
• 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

NCT02268474 is a completed study record for a prospective comparison of a 532nm KTP laser and a 595nm pulse dye laser for erythematotelangiectatic rosacea and papulopustular rosacea. The study is described as single-center and split-face, with assessment 6 weeks after the final treatment. The primary outcome is a mean Physician's Global Assessment Scale improvement score based on physician assessment of subject photographs.

The record lists enrollment as 22, but the arm description refers to 20 subjects. It describes the study as randomized while listing allocation as NA and warning against interpreting it as a randomized comparison. No primary outcome results or analyses are reported. Serious adverse events and deaths are listed as 0 in each treatment group; other adverse events are recorded for 22 of 22 at risk in each group, without event terms. The registry record describes the study question and endpoint but does not provide the comparative results needed to assess treatment effects.