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 Clinical Evaluation of the Phototoxic Potential of Xenaderm Ointment (NCT00644917), a randomized phase 1 study. The primary outcome is Skin Reaction Score.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00644917 |
| Phase | Phase 1 |
| Condition | Healthy |
| Allocation | Randomized |
| Design model | Single Group |
| Masking | Quadruple |
| Enrollment | 38 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Healthpoint |
| Results posted | Yes |
2. Clinical Question
Population
The registry describes the participants as healthy and identifies the primary-outcome population as Intent-to-Treat (ITT). Enrollment is listed as 38. The adverse-event record lists 36 participants at risk, and the registry does not explain the difference between these figures.
Intervention
The intervention is Xenaderm, described in the trial title as an ointment. The study question concerns whether exposure to light is associated with toxic skin reactions after use of the product. The registry does not describe the application procedure or the light-exposure protocol.
Comparator
Placebo is listed as a drug intervention and as a placebo comparator. The arm descriptions also state that subjects serve as their own controls. These descriptions do not explain how treatment, placebo, and self-control observations were arranged.
Primary question
The primary endpoint is Skin Reaction Score at 48 hours, measured on a scale from 0 (no reaction) to 7 (large vesiculo-bullous reaction). The registry record does not post a numerical mean, standard deviation, or a single comparison for this endpoint. It therefore does not establish the size or precision of any difference in skin-reaction scores.
3. Trial Design
This is a Phase 1 randomized study with quadruple masking and a single-group model in the registry. The record lists Xenaderm and placebo as interventions, while the arm descriptions identify a drug arm, a placebo-comparator arm, and subjects serving as their own controls. The record does not explain how those descriptions correspond to the single-group model, how allocation was implemented, or how the self-control observations were arranged. Those design details are not reported in the registry record.
The listed condition is Healthy. Enrollment is 38, the study status is completed, and both the start and primary-completion entries are 2008-02. The sponsor is Healthpoint. These entries describe the registered study but do not provide information about adherence, the number of participants contributing to the primary endpoint, or the procedures used to assess the outcome.
The study’s stated purpose is to evaluate whether exposure to light causes toxic reactions on the skin. The primary measure is a skin-irritation score assessed at 48 hours. Although the registry identifies randomization and quadruple masking, it does not specify who was masked, how the masking was maintained, or whether the outcome assessors followed a particular assessment procedure. It also does not report a protocol, allocation sequence, sample-size justification, or interim analyses.
The registry lists one outcome measure and zero analyses. It also indicates that the primary outcome includes several categories or time points and was not reduced to a single comparison. Consequently, the registered design features can be described, but the analysis approach and the primary outcome result cannot be reconstructed from this record. The planning assumptions associated with sample-size illustrations are not evidence of the trial’s actual allocation or analysis plan.
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 | Xenaderm Ointment - Subjects Acted as Own Comparator |
|---|---|
| STARTED | 38 |
| COMPLETED | 36 |
| NOT COMPLETED | 2 |
Reasons for not completing this period:
| Reason | Xenaderm Ointment - Subjects Acted as Own Comparator |
|---|---|
| Withdrawal by Subject | 2 |
Analysis population for the primary outcome, as defined in the registry: Intent-to-Treat (ITT)
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 | Xenaderm vs. Vehicle - Subjects Acted as Own Comparator |
|---|---|---|
| Participants analysed | 38 | |
| Age, Categorical: <=18 years | Participants | 1 |
| Age, Categorical: Between 18 and 65 years | Participants | 37 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age, Continuous | years | 37.5 (SD 10.7) |
| Sex: Female, Male: Female | Participants | 20 |
| Sex: Female, Male: Male | Participants | 18 |
| Region of Enrollment: United States | participants | 38 |
6. Primary Endpoint
The registry lists the primary outcome as Skin Reaction Score, measured over 48 hours.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | units on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is Skin Reaction Score, recorded in units on a scale and assessed at 48 hours. The registry describes the score as a grading of phototoxic skin irritation. The scale ranges from 0, meaning no reaction, to 7, meaning a large vesiculo-bullous reaction, with grades in whole units. The stated primary population is Intent-to-Treat (ITT).
A skin-reaction score provides a structured way to record the degree of irritation rather than relying only on an unstructured description. In general, a graded endpoint can summarize observations along an ordered scale, while a mean describes the average score and a standard deviation describes how spread out individual scores are around that average. Those are general interpretations of the listed summary measures; they do not establish how scores were distributed in this study.
The registry specifies the endpoint type as a continuous measure, with mean and standard deviation as the summary statistics. However, it does not report the observed mean or standard deviation, nor a treatment contrast based on those summaries. The record also flags that the primary outcome covers several categories or time points and was not reduced to a single comparison. Without a posted comparison, the score definition alone cannot indicate the magnitude or precision of a difference between Xenaderm, placebo, or self-control observations.
The 48-hour assessment is the stated timeframe for this endpoint. The registry does not describe other assessment procedures or explain how multiple outcome categories or time points relate to this timeframe. That information is not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted record does not contain a numerical result for the primary Skin Reaction Score. It identifies the measure, its scale, its 48-hour timeframe, and the intended ITT population, but no mean, standard deviation, treatment contrast, confidence interval, or test result is reported. The registry lists zero analyses and marks the primary outcome as having several categories or time points that were not reduced to a single comparison. Accordingly, the primary result cannot be summarized as an estimated difference between treatment conditions.
This absence of a numerical comparison is important for interpretation. A scale definition states what scores mean, but it does not show which scores participants received. Without the observed summaries or an analysis, the magnitude of any observed skin reaction and the variation between observations cannot be determined from the registry record. It is also not possible to assess statistical uncertainty or determine whether any comparison would be compatible with a range of effects.
In general, an estimate describes the observed contrast, while a confidence interval describes the uncertainty around that estimate under the assumptions of the analysis. Neither is reported for the primary endpoint. A p-value is also not reported. Therefore, the record does not support a conclusion about statistical significance, and the scale endpoints should not be treated as observed trial results.
The safety listing provides separate information. For the Xenaderm Ointment group in which subjects acted as their own comparator, the record lists 36 at risk for serious adverse events and 0 affected. It lists 36 at risk for other adverse events and 3 affected. Deaths are recorded as null, which means a death count is not reported in the registry record; it should not be interpreted as a reported count of zero. The registry does not define the other-adverse-event category in this entry or explain the relation between its risk set and the enrollment figure.
The record’s planning assumptions describe sample-size illustrations based on a fraction of the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such illustrations are planning calculations, not observed power or evidence that the study was designed or analyzed in that way. The registry record does not report the observed effect used for the illustrations or a sample-size justification for the trial itself.
9. Statistical Methods Explained
The registry identifies a continuous primary outcome summarized using a mean and standard deviation, but it does not report primary-outcome analyses. The explanations below describe general statistical concepts relevant to those choices; they are not claims about analyses performed in this trial.
What does the mean represent?
For a continuous measure, the mean is the arithmetic average of the recorded values in the analysis population. In a skin-reaction scoring context, it can give a compact description of the average score. It does not show the full pattern of individual scores: different distributions can share the same mean. The registry specifies the mean as the intended summary, but no observed mean is reported, so the average score cannot be described.
What does the standard deviation add?
The standard deviation describes how dispersed observations are around their mean. A smaller spread indicates that observed values tend to lie closer to the mean, while a larger spread indicates greater dispersion. This is a general interpretation, not a statement about the trial’s actual variability. No standard deviation for the primary score is reported in the registry record.
Why does the comparison structure matter?
An estimate of a treatment contrast depends on which observations are compared and how they are related. A parallel-group comparison and a comparison using participants as their own controls have different structures. In general, paired observations from the same participant are related, and an analysis should account for that relationship. The registry lists randomized treatment and placebo interventions, a single-group model, and an arm description in which subjects serve as their own controls. It does not explain how these features were combined or what statistical model was used. No particular comparison or model can therefore be attributed to the study.
What would a confidence interval tell a reader?
In general, a confidence interval gives a range of values compatible with an estimate under the statistical model and its assumptions. It communicates precision as well as direction and magnitude. A narrow interval indicates greater precision than a wide interval, while an interval spanning values on either side of a null contrast can indicate uncertainty about the direction of an effect. These are general principles only. The registry does not report a primary-outcome estimate or confidence interval, so precision cannot be evaluated for the skin-reaction result.
Why consider the distribution of a score?
General methods for continuous outcomes often rely on assumptions about the distribution of observations or model residuals. A mean and standard deviation do not by themselves establish whether such assumptions are reasonable. For a bounded graded scale, observations are constrained by the scale limits, and the whole-unit grading may produce a limited set of possible values. This can matter when selecting or checking an analysis method. The registry record does not report a distributional assessment, diagnostic plots, or a rationale for a particular model, so no claim can be made about whether the chosen approach addressed these considerations.
What does the planning illustration mean?
In general, a sample-size calculation estimates how much information a future study may need under specified assumptions about an effect, variability, allocation, significance level, and analysis. The registry describes planning illustrations that use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The target effect is described as a stated fraction of the observed effect. These are assumptions for planning illustrations, not a report of actual power in the completed trial. They do not establish the study’s original design rationale, because the registry record does not report a sample-size justification or the planning inputs used when the trial was designed.
The record says that time-to-event illustrations use a total number of events, while other illustrations use participants per arm. That general distinction does not make the primary endpoint a time-to-event outcome: the registered primary measure is a continuous skin-reaction score. No numerical planning output or observed effect is reported in the registry record, so no planning target or achieved precision can be stated.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies the primary population as Intent-to-Treat (ITT), but it does not report the analysis steps used to define or apply that population. In general, an ITT analysis aims to retain participants in their randomized groups, regardless of adherence or treatment received. The label alone does not show which participants had usable endpoint data, how missing observations were handled, or whether every randomized participant was included in an analysis. Those details are not reported in the registry record.
The record lists one outcome measure and zero analyses. It also flags that the primary outcome has several categories or time points and was not reduced to a single comparison. This limits interpretation because a reader cannot identify a posted primary contrast or determine how the multiple outcome elements were handled. The registry record does not report a multiplicity adjustment, a hierarchy of outcomes, or a rule for selecting among categories or time points.
In general, multiplicity arises when several hypotheses or comparisons are assessed; without suitable planning or adjustment, the chance of at least one false-positive finding can increase. That general concern does not establish that a particular error occurred in this study. The registry does not report how many inferential tests were performed or whether any adjustment was used.
Missing-data methods are also not reported in the registry record. There is no description of the amount or pattern of missing primary-outcome data, imputation, sensitivity analyses, or exclusions from the analysis population. The registry’s ITT designation should therefore be read as a stated population label, not as evidence that missing observations were resolved in a particular way. The posted record does not permit assessment of how missingness or multiplicity affected the primary result.
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 |
|---|---|---|---|
| Xenaderm Ointment - Subjects Acted as Own Comparator | 0 | 36 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Xenaderm Ointment - Subjects Acted as Own Comparator | 3 of 36 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Xenaderm Ointment - Subjects Acted as Own Comparator |
|---|---|---|
| Skin Irritation | Skin and subcutaneous tissue disorders | 3 of 36 |
The safety entry is for Xenaderm Ointment in the group described as subjects acting as their own comparator. It lists 36 participants at risk for serious adverse events and 0 affected. For other adverse events, it lists 36 at risk and 3 affected. These are the registry’s counts; no percentages or additional totals are inferred.
The record does not define the other-adverse-event category in this entry, provide event descriptions, or state how events were judged related to treatment. It also does not describe observation time or explain why the at-risk count differs from the enrollment figure of 38. These details are not reported in the registry record, so the counts should be read within the limits of the information recorded.
Deaths are shown as null. Null is not a reported zero count; it indicates that a death count is not reported in the registry record. The serious-event figure is separate from the other-adverse-event figure, and the entry should not be treated as a complete account of all safety outcomes. The record does not provide a comparative safety analysis or inferential estimate.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a completed Phase 1 study was registered to assess the phototoxic potential of Xenaderm ointment in healthy participants. Its primary measure was a skin-irritation score at 48 hours, graded on a whole-unit scale from 0 (no reaction) to 7 (large vesiculo-bullous reaction). It also records a placebo comparator and subjects serving as their own controls. These details describe the study question and measurement, not the observed primary result.
No numerical primary-outcome result or single comparison is reported. The record therefore does not show the average score, its variability, the direction or size of a contrast, or the precision of an estimate. A lack of a posted estimate is not evidence that scores were equal, and it does not establish that a difference was present. The record does not support either conclusion.
The safety counts report 0 serious adverse events among 36 at risk and 3 other adverse events among 36 at risk in the listed Xenaderm group. These figures are descriptive entries, not a comparison with a separate group. The death count is not reported in the registry record. The available safety information does not establish causation, comparative risk, or the full safety profile.
More broadly, the registered design labels do not substitute for an analysis plan or results. The record does not explain the relationship between randomized treatment, placebo, the single-group model, and self-control observations. It does not report methods for missing data or multiplicity, or how the ITT population was implemented. Those omissions constrain what can be inferred from this record; they do not imply a particular unreported finding.
13. Why This Trial Matters Statistically
This study illustrates why a registered endpoint and a posted result are different kinds of information. The registry defines the Skin Reaction Score, its scale, timeframe, and summary statistics. Those details help readers understand what investigators intended to measure. Without numerical outcome summaries or an analysis, however, the measure cannot answer how scores varied or what contrast was observed.
The design descriptions also raise an important statistical issue. The record identifies randomization and a single-group model, and it describes both placebo comparison and participants serving as their own controls. In general, the choice between independent-group and within-participant comparisons affects the analysis because observations made on the same person are related. Since the registry does not explain the operational design or analysis, readers cannot determine which comparison structure generated the planned result.
The safety listing further demonstrates the importance of keeping denominators and outcome definitions visible. It reports at-risk counts of 36 for serious and other adverse events, while enrollment is 38. The registry does not explain this difference. It also distinguishes serious events from other adverse events and leaves deaths unreported rather than giving a numerical count. Those distinctions should be retained rather than collapsed into a single safety summary.
Finally, the record’s planning assumptions should not be confused with evidence about the completed study’s statistical power. Planning calculations depend on assumptions, while observed precision depends on the data and analysis. The registry record does not report the primary effect or its uncertainty. This makes transparent reporting of estimates, analysis populations, and uncertainty especially important for interpreting a clinical trial.
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.
A central limitation is the absence of a numerical primary-outcome analysis. Although the registry specifies the Skin Reaction Score and its scale, it does not report a mean, standard deviation, comparison, confidence interval, or test result. It also marks the primary outcome as involving several categories or time points without reducing it to a single comparison. The record therefore does not provide a result from which the magnitude or precision of a primary contrast can be assessed.
The design is not fully described. Randomization, quadruple masking, a single-group model, a placebo comparator, and self-control observations are all listed, but the registry does not explain their relationship. Allocation procedures, masking roles, treatment sequence, and the handling of within-participant observations are not reported in the registry record. These omissions prevent reconstruction of the comparison structure.
The record identifies an ITT population but does not describe which participants contributed primary-outcome data, how missing observations were handled, or whether sensitivity analyses were performed. It does not report a multiplicity strategy despite noting several outcome categories or time points. It also does not provide a sample-size justification or interim-analysis information.
For safety, the listed at-risk count is 36, compared with an enrollment entry of 38, and the registry does not explain the difference. The other-adverse-event category is not defined in the entry, and deaths are not numerically reported. The record also does not state the observation period for the safety counts. These limitations concern reporting in the registry record; they should not be filled in by assumptions about trial conduct.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Clinical Evaluation of the Phototoxic Potential of Xenaderm Ointment — NCT00644917.
- Registry record last updated 2014-01-13; status last verified 2013-12.
- Results first posted 2014-01-13.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry record describes NCT00644917, Clinical Evaluation of the Phototoxic Potential of Xenaderm Ointment, as a completed Phase 1 randomized, quadruple-masked study with a single-group model. The condition is Healthy, enrollment is 38, and the sponsor is Healthpoint. The recorded start and primary-completion entries are both 2008-02.
The listed interventions are Xenaderm and placebo. Arm descriptions include a drug arm, a placebo-comparator arm, and subjects serving as their own controls. The primary endpoint is Skin Reaction Score at 48 hours, summarized as a mean and standard deviation in the ITT population. The scale ranges from 0 (no reaction) to 7 (large vesiculo-bullous reaction), in whole units.
The registry lists one outcome measure and zero analyses, and it does not report a single numerical primary-outcome comparison. The safety entry lists 0 serious adverse events and 3 other adverse events among 36 at risk in the Xenaderm self-comparator group. Deaths are not reported in the registry record.