Combined Photodynamic and Pulsed Dye Laser Treatment of Port Wine Stains: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Combined Photodynamic and Pulsed Dye Laser Treatment of Port Wine Stains (NCT00556946), a na na study. The primary outcome is Blanching of Port Wine Stain Birthmark.

2. Clinical Question

In practical terms, the study asks whether blanching was recorded among participants receiving the registered treatment. It does not set out a randomized comparison against pulsed dye laser alone or another control in the registry record. The summary notes that pulsed dye laser alone is a standard treatment and describes photodynamic therapy, alone or combined with pulsed dye laser, as investigational; these statements provide context for the research question, not a comparative result. The registry records 17 participants enrolled, but does not state how many contributed data to the primary measure. Because no primary outcome result or analysis is reported, the clinical question cannot be answered from the posted results. The record also does not report the assessment procedure, the criterion for counting a participant as having blanching, or whether the outcome was assessed by a masked evaluator.

3. Trial Design

The registry describes a completed, single-group study sponsored by the University of California, Irvine. Enrollment was 17. The recorded start is 2005-08 and primary completion is 2014-10. The phase is not reported in the registry record. Allocation is also not reported in the registry record, and masking is listed as none.

The registered intervention is named combined photodynamic and pulsed dye laser treatment. The study summary describes intravenous verteporfin for photodynamic therapy, and says the research was designed to examine photodynamic therapy or photodynamic therapy immediately followed by pulsed dye laser treatment. The registry does not report distinct arms or separate results for these approaches. Its single-group categorization means there is no registered control group for a direct treatment comparison. The record explicitly notes that the study is not a randomized comparison and that its arms are not a like-for-like control comparison.

The primary measure is a participant count for blanching of a port wine stain birthmark, with a timeframe of 12 weeks. The registry record does not give a numerical outcome result, analysis population, or account of participants who may not have contributed an outcome. It lists one outcome measure and no analyses. The protocol’s sample-size justification, statistical analysis plan, interim analyses, and any procedures for handling missing data are not reported in the registry record. The sample-size assumptions associated with planning illustrations are not evidence of how the completed study was designed or analyzed.

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 Blanching of Port Wine Stain Birthmark, measured over 12 weeks.

The primary measure is titled “Blanching of Port Wine Stain Birthmark.” Its unit is participants, its parameter is a number, and its timeframe is 12 weeks. It therefore describes a binary outcome at the participant level: a participant is counted as having the recorded outcome or not. The registry record does not provide a numerical count, define the assessment threshold for blanching, or say how the assessment was made.

General statistical explanation: A binary endpoint can be useful when the research question concerns whether participants meet a defined outcome criterion by a specified assessment time. Reporting the number of participants with the outcome alongside the number assessed can make the result understandable. The definition and assessment method matter: without them, readers cannot tell precisely what counted as blanching or how consistently it was evaluated.

The 12-week timeframe identifies when the endpoint was intended to be measured; it does not, by itself, establish how long any change lasted. The registry record does not report later follow-up for this endpoint. Nor does it report the number of participants who met the endpoint or an estimate of uncertainty around that count. Thus, the endpoint is identifiable, but its observed result and precision cannot be evaluated from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What can be inferred from a single-group design?

The registry categorizes this study as single-group and does not list a comparator. That means the registered design does not provide a concurrent control group against which the participants’ outcomes can be compared. A single-group study can describe what happened among participants, but even a clearly reported change would not establish that the intervention caused it. General explanations for a change could include the course of the condition, measurement variability, or other influences; the registry does not report methods to distinguish such explanations.

The record lists allocation as not reported in the registry record and masking as none. Masking can reduce the influence of knowledge about treatment assignment on outcome assessment or other study procedures. Since masking is listed as none, readers should not assume the outcome assessment was blinded. The record does not say who assessed blanching or how the assessment was standardized.

How should a binary outcome be analyzed?

General statistical explanation: A binary participant outcome is typically described by the number meeting the outcome and the number assessed. An estimate of the proportion can also be reported, accompanied by an interval that conveys uncertainty. The denominator matters because it identifies how many participants contributed information. These are general reporting principles, not analyses reported for this study.

The registry supplies the endpoint title, unit, parameter, and timeframe, but no observed endpoint count or denominator. It also lists zero analyses. It is therefore not possible to reconstruct an outcome estimate, confidence interval, hypothesis test, or adjusted analysis from the registry record. No p-value or confidence interval is reported. No additional calculation should be treated as a trial result when the underlying outcome data are absent.

What does an interval estimate mean?

General statistical explanation: A confidence interval expresses the uncertainty associated with an estimated quantity under the assumptions of the analysis. A narrow interval indicates greater precision than a wide interval, while neither width nor position alone establishes that a result is important. An interval for a treatment contrast is most informative when the study design supports that contrast. No confidence interval is reported for the primary measure in this registry record.

What can a planning illustration tell readers?

General statistical explanation: Sample-size planning asks how many participants a future study might need to have a specified chance of detecting an effect under stated assumptions. It is distinct from observed power, which should not be used to reinterpret an observed result after the fact. The planning assumptions associated with this record describe two-sided significance level 0.05, equal allocation between two arms, a normal approximation, and an effect stated as a fraction of the observed effect. Those are assumptions for a planning illustration, not evidence that this trial had two arms or used that design.

The registry record does not report the observed effect estimate used for that illustration, a protocol sample-size justification, or the study’s statistical analysis plan. The planning assumptions therefore cannot establish the trial’s intended design, its ability to answer the primary question, or the precision of an unreported outcome. Any sample-size illustration based on an observed effect is for planning, not a measure of the probability that this completed study detected an effect.

Why can over-dispersion matter?

General statistical explanation: Over-dispersion occurs when the variability in data is greater than a statistical model assumes. If it is ignored, uncertainty can be understated and statistical conclusions can appear more precise than warranted. The endpoint is a participant-level binary count, and the registry record does not report an analysis model or enough outcome data to assess over-dispersion. It would be inappropriate to claim that over-dispersion was present or that a particular correction was used.

More broadly, a complete statistical interpretation would depend on a prespecified outcome definition, a clearly stated analysis population, observed counts, and methods for uncertainty and missing data. These details are not reported in the registry record. The available design and endpoint descriptions identify the question the study set out to examine, but they do not replace its missing outcome analysis.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Treatment of Port Wine Stains")
n      <- c(16)
events <- c(16)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Treatment of Port Wine Stains  16  16  100.0  79.4  100.0  80.6  100.0  80.5  99.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and zero analyses. It does not report a statistical analysis plan, a hierarchy of endpoints, a multiple-testing procedure, or whether other outcomes were assessed but not entered in the registry. A single listed measure does not establish that only one outcome was considered during the research, so the handling of multiplicity is not reported in the registry record.

The record does not give the number of participants assessed for the primary measure, the number with missing outcome data, or reasons for any missing observations. It also does not describe imputation, exclusions, or sensitivity analyses. Without those details, readers cannot determine whether the outcome count represents all enrolled participants or a subset, or how missingness may have affected interpretation.

No analysis population is identified. The registry does not state whether analyses were intended to include all enrolled participants, only those receiving treatment, or participants with an available 12-week assessment. These approaches answer different questions, so the population used for analysis is important context for interpreting any result. Because no primary outcome result or analysis is reported, the registry record does not permit an assessment of multiplicity adjustments, missing-data effects, or differences between analysis populations.

12. 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.

For the listed treatment group, the registry records 17 participants at risk for serious adverse events and 0 affected. It also records 17 participants at risk for other adverse events and 0 affected. These are the counts entered in the adverse-event record; they do not replace a complete account of what was monitored, how events were defined, or how long participants were followed.

The deaths field is null, so deaths are not reported in the registry record. The record lists no top serious-event terms. A zero in the affected count means no events are entered in that field; it should not be interpreted as proof that no adverse experiences occurred or that a treatment has no risks. The registry does not describe collection procedures, reporting thresholds, or whether the adverse-event observation period corresponds to the 12-week primary-outcome timeframe.

These safety entries are descriptive counts. With no comparator group, they do not provide a controlled estimate of comparative safety. The registry record also does not report an analysis of adverse events or uncertainty around the counts.

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

The record establishes that a completed study enrolled 17 participants with port wine stains and designated the number with blanching at 12 weeks as its primary measure. It also identifies the registered intervention as combined photodynamic and pulsed dye laser treatment. These design details describe the research question and the way the study was registered; they are not evidence that blanching occurred.

The primary outcome value is not reported in the registry record. There is no count of participants with blanching, no denominator for the 12-week assessment, and no analysis or interval estimate. As a result, the posted information cannot establish the observed frequency of the endpoint, how precisely it was estimated, or whether the finding differed from any comparator. No comparator is listed.

Even if an outcome count were available, a single-group result would describe the participants in the study rather than provide a randomized estimate of what treatment caused. A comparison with pulsed dye laser alone is not reported. The study summary’s explanation of the research rationale and the status of the approaches as investigational do not substitute for outcome data.

The safety record lists 0 participants affected for serious adverse events and 0 for other adverse events, with 17 at risk in each field. That is a description of the entered registry counts, not a general guarantee of safety. The deaths field is not reported in the registry record.

Overall, the available record identifies a clinical question but does not provide the primary result needed to answer it. It neither demonstrates benefit nor demonstrates lack of benefit. A numerical outcome, its assessment definition and denominator, and a suitable comparative design would be needed for stronger conclusions about treatment effects.

14. Why This Trial Matters Statistically

This study illustrates why a clearly named endpoint is only one part of a usable clinical result. The registry specifies blanching of a port wine stain birthmark, a participant-count measure, and a 12-week timeframe. Those details identify what outcome was intended and when it was to be assessed. Without the observed count and denominator, however, readers cannot describe the endpoint’s frequency or precision.

The single-group design is also central to statistical interpretation. It can support a description of outcomes among treated participants if those outcomes are reported, but it does not supply a control-based estimate of what would have happened under another treatment or no treatment. This distinction helps prevent a descriptive observation from being mistaken for a causal comparison.

The registry record further shows why analysis transparency matters. It lists one outcome measure and no analyses, and does not report an analysis population, missing-data procedures, or a statistical plan. Such information is needed to assess how the outcome was defined, who contributed data, and how uncertainty was handled. Planning assumptions do not fill those gaps: sample-size illustrations are not the trial’s own design justification and are not observed power.

Finally, the safety entries illustrate the difference between a recorded zero and a comprehensive safety conclusion. Counts of zero affected participants are useful descriptive information, but their interpretation depends on definitions, monitoring, follow-up, and reporting. Those details are not reported in the registry record. The study is therefore statistically instructive both for the question it registered and for the limits created by absent outcome and analysis results.

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.

The most direct limitation is that the registry record does not report a numerical primary outcome result. The number assessed at 12 weeks, the number with blanching, and any estimate of uncertainty are absent. The record also does not define the criterion for blanching or describe who assessed it, making the intended endpoint difficult to evaluate beyond its title and timeframe.

The study is categorized as single-group and does not list a comparator. Thus, the record does not support a direct comparison with pulsed dye laser alone or another control. Although the study summary discusses photodynamic therapy alone as well as photodynamic therapy followed by pulsed dye laser, the intervention record does not provide separate outcome results for these approaches. Their relative outcomes cannot be assessed.

Enrollment was 17, but the number contributing to the primary measure is not reported. Participant flow, missing outcome information, analysis population, and missing-data methods are also not reported in the registry record. Masking is listed as none, while assessor procedures are not described. The record lists zero analyses and does not report a statistical plan, sample-size justification, or interim analyses. These gaps prevent assessment of analysis choices, precision, and the handling of potential bias.

For safety, the registry gives zero affected participants in the serious and other adverse-event fields, with 17 at risk in each, but does not report event definitions, monitoring procedures, or a follow-up period for those entries. The deaths field is not reported in the registry record. These limitations concern what can be learned from the posted record; they do not establish that unreported outcomes or procedures did or did not occur.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Combined Photodynamic and Pulsed Dye Laser Treatment of Port Wine Stains — NCT00556946.
• Registry record last updated 2022-10-21; status last verified 2022-10.
• Results first posted 2016-04-19.
• 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

The University of California, Irvine sponsored this completed, single-group study of treatment for port wine stains. Enrollment was 17. The registry records a start of 2005-08 and primary completion of 2014-10. The phase and allocation are not reported in the registry record; masking is listed as none.

The registered intervention is combined photodynamic and pulsed dye laser treatment. The primary measure is the number of participants with blanching of a port wine stain birthmark at 12 weeks. The registry lists one outcome measure and zero analyses, but does not report a numerical primary outcome result, its denominator, or an analysis.

For adverse events, 17 participants are listed at risk and 0 affected in each of the serious and other adverse-event fields. Deaths are not reported in the registry record. The single-group design does not provide a registered control comparison, and the posted results do not establish a treatment effect or a comparative safety estimate.