Comparison of Electrodessication, Potassium Titanyl Phosphate (KTP) Laser and Pulsed Dye Laser for Treatment of Cherry Angiomata: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of Electrodessication, Potassium Titanyl Phosphate (KTP) Laser and Pulsed Dye Laser for Treatment of Cherry Angiomata (NCT00791908), a randomized na study. The primary outcome is Mean Changes in Color, Texture, and Size of Cherry Angiomata From Baseline to 3 Months After the Second Treatment by Treatment Type as Assessed by Blinded Raters.

2. Clinical Question

The registry’s stated objective is to compare the two laser approaches with each other and with electrodessication. It describes assessment by a physician provider and the subject in the study summary, while the specified primary outcome describes ratings by 2 blinded dermatologists. The record does not report primary outcome values, so the size or direction of any differences among treatments cannot be established from the posted results.

3. Trial Design

The registry record lists this as a randomized study with single masking and a single-group model. Its treatment descriptions clarify that each participant received PDL, KTP laser and electrodessication on separate areas of the torso, with the areas randomly selected. Each treated area bore 4 cherry angiomas. This is therefore described as a within-participant comparison of treatment areas, although the registry’s model classification is “single group.” The record does not explain the randomization procedure, how treatment areas were assigned, or whether treatment order was randomized.

The planned treatment period is described as 6 weeks. The primary outcome timeframe is baseline and 3 months, and its title specifies assessment 3 months after the second treatment. The registry record does not give more detail about visit timing, the timing of the second treatment, or how assessments were scheduled across participants.

The enrollment is 15. The record does not report a sample-size justification or the assumptions used to determine enrollment. It lists the study as completed, but the primary outcome results and a statistical analysis are not reported in the registry record. The record identifies Northwestern University as sponsor. Additional details about sites, participant eligibility, participant characteristics, or protocol deviations 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 Mean Changes in Color, Texture, and Size of Cherry Angiomata From Baseline to 3 Months After the Second Treatment by Treatment Type as Assessed by Blinded Raters, measured over Baseline and 3 months.

The primary outcome is the mean change in color, texture and size of cherry angiomas from baseline to 3 months after the second treatment, considered by treatment type. Standardized photographs were evaluated by 2 blinded dermatologists using visual analog scales from 0 to 10. The scale descriptions anchor color from skin colored at 0, through red at 5, to purple at 10; texture from flat at 0, through mildly elevated at 5, to elevated at 10; and size from 0 mm at 0 to 10 mm at 10.

These ratings turn visual features into recorded scores, permitting changes in the assessed features to be described and compared across treatment areas. Blinding the raters is intended to reduce the influence of knowing which treatment was applied when they assess the photographs. The registry lists the outcome unit as units on a scale and the dispersion as full range. It does not provide the mean changes, ranges, or treatment comparisons, so the recorded endpoint definition alone does not show whether scores changed or how treatments differed.

Although the study summary also mentions assessments by a physician provider and the subject, the primary endpoint description specifies the two blinded dermatologists’ photographic ratings. Separate results for subject assessments or other physician assessments are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record supplies an outcome definition and design description, but not the statistical analysis used to generate results. The explanations below distinguish general statistical principles from what the record says about this trial. The specific model, tests, adjustment procedures and handling of missing measurements are not reported in the registry record.

What does randomization mean in this design?

In general, random allocation uses chance to determine which intervention is assigned to a unit. Here, the record says that each participant received all three treatments on separate randomly selected torso areas. It does not describe the randomization sequence or clarify precisely how areas were assigned. Because all treatments were used within each participant, treatment comparisons could be made within participants rather than only between separate groups of people. In general, this can help control for characteristics shared by areas from the same person. It does not remove every possible source of bias, and the record does not explain how the analysis accounted for the design.

Measurements from the same participant may be statistically associated. General methods for repeated or clustered observations account for this association rather than treating every measured area as entirely independent. Which method would be appropriate depends on the measurement unit and the data structure. The registry record does not report whether the analysis used participant-level summaries, area-level measurements, angioma-level measurements, or another approach.

What does the primary outcome measure?

The specified outcome is mean change from baseline in color, texture and size, assessed at 3 months after the second treatment. Each feature is scored on a 0-to-10 scale with verbal or dimensional anchors at selected values. The raters used standardized photographs, and the registry describes them as blinded dermatologists. In general, blinding can reduce the chance that an assessor’s expectations influence a rating, although the registry does not report how masking was maintained or assessed.

The scales are described as ordinal visual analog scales. Ordinal scores have an order, while the gaps between successive values are not necessarily guaranteed to represent equal changes in the underlying feature. A mean treats the recorded values numerically, which can be useful for summarizing scores but carries an assumption about how the scale values behave. This is a general consideration; the registry does not explain why the mean was selected, whether other summaries were considered, or how rater scores were combined.

The dispersion is listed as full range. In general, a range describes the lowest and highest values in the data and can give a sense of the span of observations. It does not describe every aspect of the distribution, and it can be affected by extreme observations. The registry record does not provide the actual ranges for the primary outcome.

How should uncertainty be understood?

General statistical estimates are more informative when accompanied by a measure of uncertainty, such as a confidence interval. A confidence interval represents a range of estimates compatible with the data under the method’s assumptions; it does not guarantee that the true value lies within that particular interval. No confidence intervals or other uncertainty estimates for the primary outcome are reported in the registry record. Since the outcome values themselves are also absent, neither the magnitude of a treatment contrast nor its precision can be assessed from the posted primary outcome information.

A test result such as a p-value, if reported, would address compatibility with a specified null hypothesis under the test’s assumptions; it would not by itself describe the size or practical importance of a difference. No p-values or hypothesis-test results for the primary outcome are reported in the registry record. The registry’s stated objectives and investigators’ hypothesis do not replace estimates or tests from an analysis.

What analysis details are missing?

The record does not report the statistical model, the comparison contrasts, adjustment for baseline scores, treatment of repeated ratings, or any plan for handling multiple outcomes or comparisons. It does not say how observations from the 2 blinded dermatologists were combined or whether agreement between raters was assessed. It also does not report the number of participants contributing primary outcome measurements at follow-up, missing-data methods, or the population used in analysis. These details matter because choices about the analysis can affect both estimates and their uncertainty.

The record lists no analysis records, and it does not provide primary outcome estimates. This means the analysis cannot be reconstructed or checked from the posted statistical information. Any account of which model, test or adjustment was used would be speculation, rather than a description of the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome names three features: color, texture and size. The study also compares three treatment approaches, and ratings were made by 2 blinded dermatologists. These features raise general questions about how many outcomes, ratings and treatment contrasts were considered in the analysis. When multiple comparisons are made, the chance of finding an apparently notable result by chance can increase; statistical plans may address this issue in different ways. No multiplicity strategy or hierarchy among the outcome features is reported in the registry record.

The registry identifies one primary outcome measure, but does not report whether each feature was analyzed separately, combined, or treated as part of a broader outcome. It also does not say which pairwise treatment comparisons were planned or whether any adjustment was used. The primary outcome results themselves are not reported, and the registry lists no analysis records.

Missing-data handling is not reported in the registry record. The record does not state whether all 15 participants contributed assessments at baseline and follow-up, whether any photographs or ratings were unavailable, or how incomplete observations were addressed. It also does not specify an analysis population, such as whether analyses included all randomized participants or only participants with complete ratings. Those omissions limit assessment of possible bias from missing measurements and prevent a reader from identifying precisely which observations would contribute to an analysis.

The record does not report interim analyses or stopping rules. It also does not provide a statistical analysis plan. The absence of these details should not be interpreted as evidence that a particular procedure was or was not used; those procedures are simply not reported in the registry record.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event entries list 15 participants at risk for each treatment group. For electrodessication, KTP laser and pulsed-dye laser, the registry records zero participants affected by serious adverse events and zero affected by other adverse events. These are the event counts posted for the groups, not a complete description of all possible harms or a guarantee that no events occurred outside the registry’s reporting.

The registry record does not provide further detail about event definitions, collection procedures, severity classifications beyond the serious and other categories, or the observation period for these counts. Death counts are not reported as numerical values in the record, so no conclusion about deaths can be drawn from the entries. The zero affected counts should be read as the recorded results for the reported categories and denominators, rather than proof that risk is absent. They also do not establish that the groups have equivalent safety profiles, particularly because comparative uncertainty estimates and analysis results are not reported.

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

The record establishes that a randomized trial enrolled 15 participants and assigned the three treatment approaches to separate randomly selected torso areas within each participant. It defines a photographic primary outcome involving changes in color, texture and size, rated by 2 blinded dermatologists on scales from 0 to 10. It also reports adverse-event counts for the treatment groups.

What the posted primary outcome information does not establish is whether any of the three characteristics changed, how large any change was, or how the treatments compared. No treatment-specific means, ranges, contrasts, confidence intervals or p-values for that outcome are reported in the registry record. The stated study objective and investigator hypothesis describe the question the trial aimed to address, not its findings. Without the outcome estimates, statistical evidence for or against a treatment difference cannot be evaluated.

Even if an estimate were available, its interpretation would depend on its uncertainty, the design and the measurement process. General statistical interpretation would consider the within-participant assignment of treatments, the relationship among observations from the same participant, the ordinal scale ratings and the use of photographic assessment. The record does not report enough analysis detail to assess those issues as applied in this trial.

The adverse-event entries record zero affected participants for serious events and for other events in each treatment group. Those entries describe the reported counts and do not show that there is no risk. Nor do they establish that the treatments are equally safe: the registry does not provide comparative safety analyses or uncertainty estimates.

Accordingly, the registry record is useful for identifying the design, intended outcome and reported event counts, but it does not provide the primary outcome results needed to judge the trial’s comparative findings. No conclusion that one approach performed better, worse or similarly to another follows from the information posted.

13. Why This Trial Matters Statistically

This trial is statistically notable for its within-participant structure. Each participant received all three procedures on separate randomly selected torso areas, so the comparison was not described as assigning different participants to separate treatment groups. In general, a design of this kind can reduce the effect of between-person differences on treatment comparisons. It also makes the analysis more dependent on correctly accounting for related measurements from the same participant. The registry record does not report the analysis method, leaving that important design-to-analysis link unclear.

The endpoint also illustrates the challenges of measuring visible characteristics. Color, texture and size are represented by ratings from standardized photographs rather than a single directly observed numerical measurement. The registry defines the scale anchors and identifies blinded raters, which helps describe how ratings were intended to be obtained. Yet the record does not report the resulting scores, how the two raters’ assessments were combined, or whether their agreement was evaluated.

Finally, the record shows why a clearly stated objective is not enough for statistical interpretation. It identifies the comparison and outcome, but the primary outcome estimates and analysis are not reported. Without those results, readers cannot assess the size or precision of treatment differences. The recorded adverse-event counts offer a separate description of reported events, but they do not resolve the missing efficacy-outcome information or establish comparative safety.

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 main limitation for interpreting this trial is that the registry record does not report the primary outcome results or a statistical analysis. Although it defines mean changes in color, texture and size, it gives no treatment-specific estimates, ranges, contrasts or uncertainty measures. The direction and magnitude of any observed differences therefore remain unknown.

The record describes a within-participant design, but does not report how the analysis accounted for measurements from treatment areas belonging to the same participant. It also does not specify the analysis unit, the handling or combination of ratings from the 2 blinded dermatologists, or the planned contrasts. The absence of a reported analysis plan makes it impossible to assess whether the statistical methods matched the design and outcome structure.

Missing-data procedures and analysis populations are not reported. The record does not state how many participants contributed complete baseline and follow-up ratings or how incomplete photographs or scores were handled. It also does not report a sample-size justification. Enrollment was 15, but the registry record does not give a basis for determining whether that enrollment was intended to provide adequate precision for the planned comparisons.

Participant characteristics, eligibility details and broader site information are not reported in the trial details. This limits assessment of which populations or settings the results might represent, even if outcome results were available. The adverse-event entries report zero affected participants in the stated categories, but event definitions, ascertainment details and death counts are not reported as numerical results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Comparison of Electrodessication, Potassium Titanyl Phosphate (KTP) Laser and Pulsed Dye Laser for Treatment of Cherry Angiomata — NCT00791908.
• Registry record last updated 2015-03-06; status last verified 2015-02.
• Results first posted 2010-12-21.
• 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.

18. Record Summary

The registry record describes a completed randomized study sponsored by Northwestern University, with enrollment of 15 participants. Each participant received electrodessication, PDL and KTP laser on separate randomly selected torso areas, with each area bearing 4 cherry angiomas. Treatment was described as occurring over 6 weeks.

The primary outcome was mean change in color, texture and size from baseline to 3 months after the second treatment, assessed from standardized photographs by 2 blinded dermatologists using scales from 0 to 10. Primary outcome estimates and statistical analyses are not reported in the registry record. The adverse-event entries report zero participants affected by serious events and zero affected by other events in each treatment group, with 15 at risk in each. These event counts do not establish that risk is absent or that the treatments are equivalent.