This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Pilot Study of a Novel 532nm KTP Laser for the Treatment of Fresh Surgical Scars (NCT01789346), a randomized na study. The primary outcome is Improvement in Surgical Scar of Treatment (532nm KTP Laser) and Active Control (595nm PDL) Treatment Arms..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01789346 |
| Phase | NA |
| Condition | Scar, Surgical Scar, Cicatrix |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 20 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Cutera Inc. |
| Results posted | Yes |
2. Clinical Question
Population
People with fresh surgical scars were the intended population. The registry lists scar-related conditions, including surgical scar, hypertrophic cicatrix and keloid. It does not report participant demographics, eligibility details, scar characteristics or the population represented in the posted outcome analysis. The record gives an enrollment of 20, while the primary outcome is reported for 18 participants in each arm; the reason for that difference is not reported in the registry record.
Intervention
The intervention was a 532nm potassium titanyl phosphate (KTP) laser, identified as the Cutera ExcelV device. The study examined its use for treatment of fresh surgical scars. The registry describes the trial as a pilot and lists safety and efficacy as its purpose. Treatment settings, number and spacing of sessions, and other procedural details are not reported in the registry record.
Comparator
The active comparator was a 595nm pulsed-dye laser (PDL), identified as the Cynosure Cynergy device. Both arms are described as laser treatment arms. The record does not report additional details about treatment schedules or whether any other aspects of care were standardized between arms.
Primary question
The primary question was how much improvement in surgical scar appearance was recorded in each arm at 12-weeks post-final laser treatment, compared with baseline. Blinded independent reviewers assessed improvement using the Physician’s Global Assessment, a scale from 0 to 3 on which higher scores indicate better outcome. The registry gives each arm’s median and 95% confidence interval, but does not report a direct between-arm estimate or statistical test. The posted summaries therefore describe the two arms separately rather than quantify the comparative effect.
3. Trial Design
This was a randomized, controlled, open-label pilot study with a parallel-group model. Random allocation means assignment to the arms was described as randomized, while the parallel model indicates that the registry presents separate groups receiving the KTP laser or the active PDL comparator. The trial’s masking status is listed as none. Separately, the primary outcome description says that blinded independent reviewers assessed the scars. These statements concern different aspects of the study: the registry labels the trial open-label, while its outcome description specifies blinded assessment. Details of how reviewer blinding was maintained are not reported in the registry record.
The registry lists an enrollment of 20 and status as completed. For the primary outcome, it reports n=18 in each arm. The record does not explain why the endpoint counts differ from the enrollment entry, nor does it provide a participant flow account. The study began in 2013-02, and primary completion is recorded as 2014-03-26. Its phase is listed as NA.
The two interventions were the 532nm KTP laser and the 595nm PDL laser. The primary assessment was scheduled for 12-weeks post-final laser treatment, with improvement measured against baseline. The registry gives no additional primary or secondary outcome analyses: it lists one outcome measure, zero analyses, and no posted secondary outcomes. Allocation concealment, randomization sequence generation, protocol deviations, treatment adherence and the statistical analysis plan are not reported in the registry record. Consequently, the design can be described from its broad registry labels, but important operational and analytical details cannot be established from the posted 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
| Stage | All Study Participants |
|---|---|
| STARTED | 20 |
| Treatment With 532 nm KTP Laser | 20 |
| Treatment With 595 nm PDL Laser | 20 |
| COMPLETED | 18 |
| NOT COMPLETED | 2 |
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.
| Characteristic | Unit | All Subjects |
|---|---|---|
| Participants analysed | 20 | |
| Age, Continuous | years | 49.4 (SD 11.7) |
| Sex: Female, Male: Female | Participants | 19 |
| Sex: Female, Male: Male | Participants | 1 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | participants | 20 |
6. Primary Endpoint
The registry lists the primary outcome as Improvement in Surgical Scar of Treatment (532nm KTP Laser) and Active Control (595nm PDL) Treatment Arms., measured over 12-weeks post-final laser treatment.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | score on a scale |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is improvement in surgical scar appearance at 12-weeks post-final laser treatment compared with baseline. Blinded independent reviewers rated improvement using the Physician’s Global Assessment, a score from 0 to 3; higher scores mean better outcome. The registry reports the endpoint as a median score for each treatment arm, with a 95% confidence interval.
A global assessment can provide a structured way to summarize a reviewer’s overall judgment of an outcome. Using the same stated scale across arms makes the arm-level summaries interpretable in common units. Reporting a median describes the midpoint of the observed scores rather than an arithmetic average. This can be useful for an ordinal rating scale, where the ordering of scores is meaningful but equal spacing between categories should not automatically be assumed.
The endpoint is an assessment of scar improvement, not a direct measure of every aspect of scar appearance, function, symptoms or patient experience. The registry does not report additional endpoint details such as separate scar features, a threshold defining clinically meaningful improvement, or the number of reviewers per assessment. It also does not report a direct comparative estimate for the arms. The posted scores therefore indicate the reported arm-level ratings at the specified assessment time, but do not by themselves establish the size or uncertainty of a treatment contrast.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The KTP arm has a reported median improvement score of 2.0, with a 95% confidence interval from 1.0 to 2.5. The PDL arm has a reported median of 1.5, with a 95% confidence interval from 0.0 to 2.0. Each arm’s primary outcome count is 18. These are separate summaries of improvement from baseline, scored on the Physician’s Global Assessment scale on which higher scores indicate better outcome.
The registry does not report a direct estimate of the difference between arms, a confidence interval for that difference, or a test of the comparative hypothesis. It also lists zero analyses. As a result, the posted medians should not be treated as a formally tested comparison. Although the median reported for KTP is numerically higher than the median reported for PDL, that observation alone does not quantify the uncertainty in a between-arm effect or establish whether the arms differ statistically or clinically.
A confidence interval describes uncertainty around an estimate under the method used to construct it. The registry labels the intervals as 95% confidence intervals, but does not report how they were calculated. They are intervals for the arm-level median summaries, not a confidence interval for a contrast between the arms. Their overlap or lack of overlap is not a substitute for a direct comparative analysis; even where intervals overlap, a proper comparison requires an estimate and uncertainty calculated for the contrast of interest.
The study is identified as a pilot, and the registry reports an enrollment of 20. Pilot results can describe feasibility and provide preliminary outcome information, but the record does not state a sample-size justification or planned precision target. The arm-level outcome summaries have limited context without details about participant selection, missing outcome data and analysis populations. The registry gives outcome counts of 18 in each arm, but does not explain how these relate to the enrollment entry.
The appropriate reading is therefore descriptive: the posted record reports median improvement scores and their intervals for both laser arms at the specified follow-up. It does not provide enough inferential information to establish the magnitude, precision or statistical significance of a comparative effect. No conclusion about whether one device is superior, equivalent or noninferior follows from these arm-level statistics alone.
9. Statistical Methods Explained
The registry identifies a randomized, open-label, parallel-group pilot and reports a median primary outcome with a 95% confidence interval in each arm. It does not report the analysis procedures used to produce those summaries, a direct treatment comparison, or a statistical analysis plan. The explanations below describe general statistical concepts, not methods confirmed to have been used in this study.
What does a median describe?
In general, a median is the middle of an ordered set of observations. It is a measure of location, but it is not the same as an arithmetic mean. For an ordinal rating scale such as the Physician’s Global Assessment, the median reflects the central score after ordering the observations. It does not show the full distribution: two sets of scores can share a median while differing in how their other observations are distributed. The posted record gives the median for each arm, but does not provide the individual scores or a fuller distribution.
What does a confidence interval communicate?
In general, a confidence interval expresses the uncertainty of an estimate under a specified statistical procedure. A 95% confidence interval is commonly interpreted through the long-run behavior of that procedure: across repeated comparable studies, intervals constructed in the same way would include the target quantity at the stated rate, if the method’s assumptions hold. It is not a range containing 95% of individual participant scores, and it does not mean there is a 95% probability that the particular interval contains the fixed underlying quantity.
The registry reports intervals for the arm medians. It does not give the interval construction method, so the assumptions and behavior of those intervals cannot be assessed from the record. Nor are the arm-specific intervals a direct interval for the difference between arms. A comparative question is best addressed by an estimate of that contrast, accompanied by its uncertainty and a description of the method used.
Why does the scale matter?
In general, a rating scale carries information about the ordering of outcomes. An ordinal scale establishes that one score represents a higher rating than another, but does not necessarily establish that the distance between adjacent score values is constant. A median is one way to summarize an ordered outcome without treating the score spacing as necessarily equal. The registry states that higher Physician’s Global Assessment scores mean better outcome and reports results on a 0-to-3 scale. It does not report a threshold for a meaningful change or a validated interpretation of differences in score.
Why is a direct comparison important?
In general, comparing treatments requires more than reading two separate group summaries. A treatment contrast directly estimates how outcomes differ between groups, and its confidence interval describes the precision of that estimate. The choice of contrast and method depends on the outcome scale, study design and analysis plan. The registry does not report such a contrast, a p-value or a test method. Therefore, no comparative inferential result can be reconstructed from the posted medians and intervals alone.
What can randomization contribute?
In general, random assignment aims to make treatment groups comparable with respect to both observed and unobserved characteristics at assignment, subject to the randomization process and the conduct of the trial. This supports interpretation of a properly analyzed between-arm contrast. It does not ensure that groups will be identical, resolve missing outcome data, or remove concerns about measurement and adherence. The registry identifies allocation as randomized but does not report sequence generation, concealment, adherence, baseline characteristics or departures from assigned treatment. Those details are needed to assess how randomization was implemented and how the analysis reflects assignment.
What do the planning assumptions mean?
In general, a sample-size planning illustration estimates the number of participants per arm needed to detect a chosen effect under specified assumptions. The registry’s planning description refers to a two-sided significance level of 0.05, equal allocation, a normal approximation and an effect defined as a stated fraction of the observed effect. These are planning assumptions, not evidence about the trial’s achieved ability to detect an effect. A planning calculation based on an observed effect is illustrative and does not amount to observed power. No planning estimate values are reported in the registry record, and the record does not report the trial’s own sample-size justification. The described assumptions should not be mistaken for a documented analysis plan or for a result of the randomized comparison.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure, zero analyses and no posted secondary outcomes. It does not report a multiplicity plan, such as a prespecified hierarchy or adjustment for testing multiple outcomes or comparisons. With no posted set of analyses or hypothesis tests, the impact of multiplicity cannot be evaluated. The absence of a reported adjustment does not establish that none was planned or performed; those details are not reported in the registry record.
The record reports an enrollment of 20 and a primary outcome count of 18 in each arm. It does not provide a participant flow account or explain the relationship between these counts. Reasons for unavailable outcome assessments, if any, are not reported in the registry record. The record also does not state whether the primary analysis used all randomized participants, only participants with observed endpoint data, or another analysis population.
Missing data can affect an estimate when participants without an observed outcome differ from those with an outcome, and the consequences depend on the amount, reasons and handling of missingness. In general, analysis choices may include assumptions about the missing outcomes, but no such approach can be attributed to this study from the posted record. The record does not report imputation, sensitivity analyses, exclusions or protocol deviations. It is therefore not possible to assess the effect of missing data or determine whether the reported endpoint summaries represent an intention-to-treat population.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| 532nm KTP Laser | 0 | 19 | 0.0% |
| 595nm PDL | 0 | 19 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| 532nm KTP Laser | 0 of 19 |
| 595nm PDL | 0 of 19 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| 532nm KTP Laser | 10 of 19 |
| 595nm PDL | 8 of 19 |
Most frequent non-serious adverse event terms
| Event term | Organ system | 532nm KTP Laser | 595nm PDL |
|---|---|---|---|
| Erythema | Skin and subcutaneous tissue disorders | 9 of 19 | 7 of 19 |
| Edema | Skin and subcutaneous tissue disorders | 2 of 19 | 2 of 19 |
| Purpura | Skin and subcutaneous tissue disorders | 3 of 19 | 1 of 19 |
| Crusting | Skin and subcutaneous tissue disorders | 2 of 19 | 0 of 19 |
| Burning Sensation | Skin and subcutaneous tissue disorders | 1 of 19 | 1 of 19 |
The registry reports serious adverse event counts of 0 in the KTP arm and 0 in the PDL arm. Deaths are also recorded as 0 in both arms. For other adverse events, the registry reports 10 affected participants among 19 at risk in the KTP group and 8 among 19 at risk in the PDL group. These are event counts as recorded in the safety summary; the registry does not provide event terms for the other adverse events in the information reported.
The safety groups’ at-risk counts are distinct from the primary outcome counts, which are 18 in each arm. These denominators should be read as the registry lists them, not assumed to represent the same analysis population as the efficacy endpoint. The record does not report the event collection period, severity grading, causality assessment, definitions, or whether participants could experience more than one event. It also lists no serious adverse event terms.
Zero recorded serious events or deaths does not demonstrate that the risk is absent. With a pilot study, the safety summaries are descriptive and cannot establish equivalence in safety between the devices. The reported other-event counts likewise do not identify the event types or establish a causal relationship to treatment.
12. What the Result Does, and Does Not, Mean
The posted results describe a randomized pilot study of two laser treatments for fresh surgical scars. For the primary outcome, the registry reports a median Physician’s Global Assessment improvement score of 2.0 for 532nm KTP and 1.5 for 595nm PDL, with arm-specific 95% confidence intervals. The scale ranges from 0 to 3, and higher scores mean better outcome. The assessment was described as occurring at 12-weeks post-final laser treatment compared with baseline and was made by blinded independent reviewers.
These summaries show the central reported score in each arm, not the full distribution of individual outcomes. They do not estimate the amount by which one treatment changes the score relative to the other. The registry does not report a direct between-arm estimate, a confidence interval for a treatment contrast, or a statistical test. It also does not report a clinically meaningful threshold for interpreting score differences. Thus, the numerical ordering of the medians is descriptive and is not sufficient to establish superiority, equivalence or noninferiority.
The safety record lists no serious adverse events and no deaths in either group, alongside other adverse event counts. These counts do not establish that serious risks are absent or that the treatments have equivalent safety; event definitions, types and collection details are not reported.
The results do not answer every question relevant to scar treatment. The registry does not provide participant characteristics, detailed treatment schedules, endpoint distributions, analysis populations, missing-data methods or longer-term outcomes. The findings are limited to the posted arm-level summaries and safety counts. They can be read as preliminary descriptive information from a pilot, but the registry record does not support a definitive comparative conclusion.
13. Why This Trial Matters Statistically
This trial matters statistically because it illustrates the distinction between reporting outcomes in each arm and estimating a treatment contrast. The registry gives a median and 95% confidence interval for each laser arm, but does not report a direct comparative estimate or test. A reader can describe the arm-level results, yet cannot infer the precision of the difference between arms from those summaries alone. This distinction is important whenever an outcome is presented by group and the research question is comparative.
The primary measure is an ordinal global assessment with a stated direction: higher scores mean better outcome. Reporting a median is a reasonable descriptive choice for an ordered scale, but a median alone hides the distribution of scores. Detailed distributional summaries and an explicitly defined treatment contrast would add information about how outcomes compare. The registry does not report those details.
The record also highlights the need to distinguish trial enrollment from endpoint and safety denominators. It reports an enrollment of 20, primary outcome counts of 18 in each arm, and safety at-risk counts of 19 in each arm. Without a participant flow account and analysis-population definitions, these counts cannot be reconciled or interpreted as interchangeable.
Finally, pilot findings and planning illustrations serve different purposes. The study is labeled a pilot, while the registry’s planning description refers to assumptions based on the observed effect. Such planning is hypothetical rather than an estimate of observed power. The record does not report a sample-size justification for the trial or provide comparative inferential analyses. Clear reporting of these distinctions helps prevent descriptive results from being overstated as definitive evidence.
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 record leaves important details unavailable for interpreting this specific trial. It does not describe the eligibility criteria, participant characteristics, scar locations or baseline score distributions. Without these details, it is difficult to assess which people and scars are represented by the outcome summaries or whether the arms had comparable starting characteristics.
The trial is labeled open-label and unmasked, while the primary outcome description says that blinded independent reviewers performed assessments. The record does not explain the assessment procedures or how reviewer blinding was maintained. Because the endpoint is a rating, information about reviewer number, agreement and scoring procedures would help readers assess measurement reliability; these details are not reported in the registry record.
Procedural details are also limited. The record identifies the devices but does not report laser settings, treatment frequency, treatment duration or adherence. The primary outcome is assessed at 12-weeks post-final treatment, but later follow-up is not reported. The registry does not give individual score distributions, a clinically important threshold, or a direct between-arm analysis.
There is no participant flow explanation for the difference between the enrollment entry and the endpoint counts. The analysis population, missing-data handling and protocol deviations are not reported. Safety information is similarly limited: the record does not provide other adverse event terms, event definitions, severity, relatedness or collection period. These omissions do not establish that particular methods or events were absent; they mean the registry record does not report them.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Pilot Study of a Novel 532nm KTP Laser for the Treatment of Fresh Surgical Scars — NCT01789346.
- 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.
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18. Record Summary
The registry describes a completed, randomized, controlled, open-label, parallel-group pilot study comparing a 532nm KTP laser with a 595nm pulsed-dye laser for fresh surgical scars. Enrollment is recorded as 20. The primary endpoint is improvement from baseline on the Physician’s Global Assessment at 12-weeks post-final laser treatment, assessed by blinded independent reviewers. Higher scores on the 0-to-3 scale indicate better outcome.
The posted primary outcome gives a median of 2.0 for KTP and 1.5 for PDL, each with a 95% confidence interval; the endpoint count is 18 in each arm. No direct comparative estimate or test is reported. The safety summary lists zero serious adverse events and zero deaths in each group, with other adverse events recorded for 10 of 19 at risk in the KTP group and 8 of 19 in the PDL group. Analysis populations, missing-data methods, detailed safety terms and the statistical analysis plan are not reported in the registry record.