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 Photodynamic Therapy Using Topical Aminolevulinic Acid in Treating Patients With Actinic Keratosis (NCT00524485), a randomized na study. The primary outcome is Protoporphyrin IX (PpIX) Accumulation as a Function of Skin Preparation, Aminolevulinic Acid Application Time, and Body Site.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00524485 |
| Phase | NA |
| Condition | Precancerous/Nonmalignant Condition |
| Allocation | Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 12 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Roswell Park Cancer Institute |
| Results posted | Yes |
2. Clinical Question
Population
Patients with actinic keratosis were the intended study population. The registry record describes the condition as precancerous or nonmalignant. It records enrollment of 12 participants, but does not report further eligibility criteria or participant characteristics.
Intervention
The intervention involved topical aminolevulinic acid (ALA) and Vbeam laser photodynamic therapy (PDT). The arm descriptions vary ALA application time, laser exposure, and treatment conditions. They describe ALA application 2 hours, 4 hours, or 24 hours before PDT; another description varies laser pulses between subunits. The record does not make the overall intervention structure fully clear.
Comparator
The record describes different treatment conditions, including differing ALA application times and laser exposure. However, it labels the study model single group while also labeling allocation randomized. It does not establish a clear primary-outcome comparison between distinct groups, and no comparator-specific outcome results are reported.
Primary question
The primary outcome concerns protoporphyrin IX (PpIX) accumulation in relation to skin preparation, the time of ALA application, and body site. This is a biological measurement rather than a direct measure of lesion clearance. The registry record does not report the measurement unit, timeframe, or any outcome values.
3. Trial Design
The registry record identifies this as a randomized clinical trial, lists the study model as single group, and records no masking. These descriptions do not resolve how participants, treatment areas, or subunits were assigned. The arm descriptions list different ALA application times and laser-treatment conditions, including randomization of anatomical subunits to laser pulse exposure in one description. The registry record does not report a complete allocation procedure or clarify how the listed arm descriptions relate to the single-group designation.
The study enrolled 12 participants and is listed as terminated. Its phase is recorded as not applicable. The study concerned actinic keratoses and combined topical ALA with laser photodynamic therapy. The stated primary outcome was PpIX accumulation as a function of skin preparation, ALA application time, and body site. Secondary outcomes concerned acute reactions, efficacy, histological response, PpIX accumulation in incidental lesions, and photobleaching by treatment light.
The primary outcome has no reported measurement unit, timeframe, numerical result, or outcome description. The registry record explains that the study began before the institute introduced centralized data entry and data management. Treatment assignments and outcomes had been entered by the principal investigator’s staff and were subsequently lost. The principal investigator died, and attempts to retrieve the data were unsuccessful. Consequently, the record supports a description of the intended study question and treatment conditions, but not a reconstruction of the analysis or its findings.
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 | Unknown Trt Arm: Aminolevulinic Acid and Laser Therapy |
|---|---|
| STARTED | 12 |
| COMPLETED | 7 |
| NOT COMPLETED | 5 |
Reasons for not completing this period:
| Reason | Unknown Trt Arm: Aminolevulinic Acid and Laser Therapy |
|---|---|
| Withdrawal by Subject | 5 |
Analysis population for the primary outcome, as defined in the registry: Study was activated prior to RPCI putting a centralize data entry and data management. Data entry of the treatment arm assignments and outcomes was done by PI's staff and has since been lost. The PI died and all attempts to retrieve the data have failed.
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.
Population: All treated and eligible patients
| Characteristic | Unit | Unknown Trt Arm: Aminolevulinic Acid and Laser Therapy |
|---|---|---|
| Participants analysed | 12 | |
| Age, Continuous | years | 62.4 (SD 15.8) |
| Sex: Female, Male: Female | Participants | 6 |
| Sex: Female, Male: Male | Participants | 6 |
6. Primary Endpoint
The registry lists the primary outcome as Protoporphyrin IX (PpIX) Accumulation as a Function of Skin Preparation, Aminolevulinic Acid Application Time, and Body Site, measured over a time frame that is not stated.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is titled PpIX accumulation in relation to skin preparation, the time of topical ALA application, and body site. PpIX is the measured biological quantity named in the endpoint. In general, a biological endpoint can help characterize a process occurring in tissue and can be useful when researchers want to examine how treatment conditions relate to a biological response. That general role does not make it equivalent to a clinical outcome such as lesion clearance or a patient-reported benefit.
The record gives no unit, timeframe, measurement description, or numerical results for this endpoint. It therefore does not establish how accumulation was quantified, when the primary measurement was taken, or how results were intended to be compared across conditions. Although secondary outcomes mention PpIX in incidental actinic keratoses and photobleaching, those descriptions do not fill in the missing primary-endpoint measurement details.
Without the outcome data, it is not possible to describe the direction, size, or precision of any observed association between PpIX accumulation and skin preparation, ALA application time, or body site. The endpoint title defines the scientific question, but the registry record does not provide a result that answers it.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
No numerical primary-outcome findings are reported. The record identifies PpIX accumulation as the primary outcome, but contains no observed values, treatment-group summaries, effect estimate, confidence interval, or hypothesis-test result. The primary outcome’s measurement unit and timeframe are also not reported in the registry record. Accordingly, the available information cannot establish whether PpIX accumulation differed across skin preparation, ALA application time, or body site, nor how precisely any difference might have been estimated.
The missing results are linked to a documented loss of treatment assignment and outcome data. The registry record says that treatment assignments and outcomes had been entered by the principal investigator’s staff before centralized data entry and management was introduced. Those data were later lost, and attempts to retrieve them after the principal investigator’s death failed. This is more consequential than an ordinary absence of a summary statistic: the record states that the underlying entries needed to report the trial’s treatment conditions and outcomes could not be recovered.
The study is labeled randomized, but its model is also labeled single group. The five arm descriptions include varying treatment times and laser conditions, yet the record does not clarify how those descriptions map to a primary-outcome comparison. It notes that fewer than two arms were available for the primary outcome. Thus there is no recorded primary-outcome contrast to interpret. This leaves the intended scientific question visible, while preventing a comparison of outcomes between treatment conditions.
The record lists 12 enrolled participants and a terminated status, but enrollment alone does not supply evidence about the endpoint. Seven outcome measures are listed, while no analyses are reported. The adverse-event record identifies an unknown treatment arm and lists 0 participants at risk and 0 affected for serious and other events; deaths are not reported as a numerical value. Given the documented data loss and unknown treatment assignment, those entries do not support a conclusion that adverse events did not occur.
In general, an estimate describes the observed size and direction of a result, while a confidence interval describes the uncertainty around that estimate under a statistical model. A p-value addresses compatibility with a specified null hypothesis under assumptions. None of these quantities is reported for the primary outcome. There is therefore no basis for a statistical conclusion about the primary question, and no basis for interpreting a treatment effect from the registry record.
9. Statistical Methods Explained
What does randomization contribute?
In general, randomization assigns treatment conditions using a chance-based procedure. When it is implemented and documented, it can help make comparison groups similar on average with respect to both measured and unmeasured characteristics. That protection depends on knowing what was randomized, how assignment was carried out, and which outcomes belong to each assignment. The registry record labels this study randomized, but does not report the allocation procedure. Its single-group model label and its descriptions of treatment arms and randomized subunits leave the allocation structure unclear. The lost assignment data further prevent checking which treatment condition was linked to each outcome.
What does the endpoint measure?
The primary endpoint concerns PpIX accumulation and names skin preparation, ALA application time, and body site as factors of interest. In general, a biological measurement can be used to investigate a treatment process without directly measuring a clinical outcome. Interpreting such a measure requires information about how it was measured, when it was assessed, and what summaries or contrasts were planned. The registry record does not report the primary endpoint’s unit, timeframe, or measurement description. Nor does it provide measured values. The title therefore communicates the intended topic, not the method or result.
What would an effect estimate and confidence interval convey?
In general, an effect estimate expresses the size and direction of a comparison on a defined scale. A confidence interval gives a range of values compatible with the observed data and statistical assumptions, and conveys the estimate’s precision. A narrow interval generally indicates greater precision than a wide interval, while neither guarantees that an estimate is free from bias. No primary-outcome effect estimate or confidence interval is reported in the registry record. Because the treatment assignments and outcomes were lost, there is no posted primary result from which to describe either the estimated effect or its precision.
Can a hypothesis test be interpreted?
In general, a p-value summarizes how compatible the observed data are with a specified null hypothesis under the assumptions of the test. It does not measure the probability that the null hypothesis is true, and it does not by itself describe the size or practical importance of an effect. Interpreting a test also requires knowing the comparison, endpoint, analysis population, and statistical method. The record reports no primary-outcome analysis, test statistic, or p-value. The primary-outcome comparison itself is not available, so a hypothesis-test interpretation is not possible.
What can be inferred from the planning illustration?
In general, sample-size planning illustrations show how a hypothetical study size may relate to an assumed effect and statistical design. They are not observed trial results and should not be confused with observed power. The record describes an illustration based on a fraction of an observed effect, with assumptions about significance level, allocation, and a normal approximation. But it does not report a usable observed primary-outcome effect from this trial. The illustration therefore cannot supply an estimate of the missing result or serve as evidence that the trial detected an effect. The trial’s own sample-size justification is not reported in the registry record.
More broadly, the record does not report the statistical analysis plan, model specification, handling of repeated or subunit-level measurements, or planned adjustment for covariates. These omissions matter because outcomes from different body sites or subunits may require a clearly specified unit of analysis and a method that respects how observations are related. That is a general design consideration, not a description of an analysis known to have been used in this study. No particular statistical model or analytical procedure can be attributed to the trial from the available record.
10. Multiplicity, Missing Data and Analysis Populations
The record lists seven outcome measures: the primary PpIX accumulation outcome and secondary outcomes concerning acute reactions, efficacy, histological response, PpIX accumulation in incidental actinic keratoses, and photobleaching. When a study examines multiple outcomes, treatment conditions, time points, or body sites, the chance of finding an apparently notable result by chance can depend on how many comparisons are made and how they are selected. In general, investigators may specify a primary comparison in advance or use a multiplicity strategy to account for several tests. The registry record does not report such a strategy, planned contrasts, or a statistical analysis plan.
No analyses are reported. The record states that treatment assignments and outcomes were lost, so the extent and pattern of missingness cannot be assessed from the posted results. The registry record does not report an analysis population, exclusions, or methods for handling missing data. It is therefore not possible to determine whether results would have been analyzed by assigned treatment, by treatment received, or using another population definition.
The record’s explanation makes clear that this is not simply a case where a small number of outcome values are omitted from an otherwise available analysis. Assignment and outcome entries could not be retrieved. Without those data, neither the completeness of endpoint measurements nor the relationship between missingness and treatment conditions can be evaluated. No adjustment for multiple comparisons or missing-data method should be inferred.
11. What the Result Does, and Does Not, Mean
The registry record documents a pilot study intended to examine topical ALA and Vbeam photodynamic therapy in actinic keratoses, with PpIX accumulation as the primary outcome. It also records a randomized designation, a single-group model, 12 enrolled participants, and a terminated status. These details describe the study’s registration and intended focus; they do not provide evidence about the primary outcome.
The record does not establish whether PpIX accumulation varied with skin preparation, ALA application time, or body site. It contains no numerical primary-outcome result and no reported analysis. It also does not provide a usable comparison between treatment conditions. The missing data prevent statements about the magnitude or direction of an effect, its precision, or whether observed differences were compatible with chance under a specified statistical model.
Even if results had been available, PpIX accumulation would address the biological endpoint named in the record, not automatically answer every clinical question about actinic keratosis. The listed secondary outcomes include efficacy and histological response, but no results for those outcomes are reported either. The registry record therefore cannot establish clinical benefit, lack of benefit, or comparative performance for any treatment condition.
In general, a trial’s enrollment count is not a substitute for outcome evidence, and an absent analysis is not evidence of no effect. Likewise, the adverse-event entries listing 0 at risk and 0 affected do not establish that no adverse events occurred, especially in the context of the stated loss of assignment and outcome data. The appropriate interpretation is limited: the scientific question and several intended treatment conditions are recorded, but the posted record does not contain recoverable findings with which to answer that question.
12. Why This Trial Matters Statistically
This study illustrates why data management and traceable treatment assignments are part of the statistical foundation of a clinical trial. Randomization can support a fair comparison only when assignment records remain linked to participants, treatment conditions, and measured outcomes. Here, the registry record reports that the treatment assignment and outcome entries were lost, and retrieval attempts failed. Without those links, the intended comparisons cannot be reconstructed from the registration description alone.
The record also illustrates the importance of a clear design description. It labels the study randomized while naming a single-group model and describing several treatment conditions, including randomization of anatomical subunits in one arm description. Such details matter because the unit assigned to treatment determines the appropriate comparison and can affect how measurements are analyzed. The available record does not resolve that structure for the primary outcome.
A further statistical lesson is that a defined endpoint is not the same as a reported result. The primary outcome title identifies PpIX accumulation and the factors of interest, but the record lacks measurement details and numerical findings. With no estimate, uncertainty interval, or analysis, readers cannot distinguish a precise null result from an imprecise estimate or from an outcome that was never recoverable. The registry record documents the data loss, but does not report the study’s analysis plan or sample-size justification.
13. 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 the loss of treatment-arm assignments and outcomes. The registry record says these entries were made by the principal investigator’s staff before centralized data entry and data management was implemented, and could not be retrieved after the principal investigator died. This prevents interpretation of the primary and secondary outcomes, and makes it impossible to verify which treatment condition corresponds to any participant-level observation.
The design description is also difficult to reconcile. The record labels allocation randomized but labels the model single group. Five arm descriptions cover differing ALA application times, laser pulse exposure, and treatment conditions, but the record does not clarify the relationship among those descriptions or identify a clear primary-outcome comparator. It notes that fewer than two arms were available for the primary outcome.
Important endpoint and analysis details are absent. The primary outcome has no reported unit, timeframe, or measurement description. The statistical analysis plan, analysis population, handling of missing data, and multiplicity approach are not reported in the registry record. The record lists seven outcome measures but reports no analyses.
The study is listed as terminated and enrolled 12 participants. The record does not report a reason for termination beyond the account of data loss, so no additional explanation should be inferred. Adverse-event reporting is limited to an unknown treatment arm with 0 at risk and 0 affected for serious and other events; deaths are not given as a numerical result. Those entries are not sufficient to characterize safety in the absence of recoverable outcome data.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Photodynamic Therapy Using Topical Aminolevulinic Acid in Treating Patients With Actinic Keratosis — NCT00524485.
- Registry record last updated 2017-06-14; status last verified 2017-05.
- Results first posted 2017-05-17.
- 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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17. Record Summary
This terminated pilot study concerned topical aminolevulinic acid and Vbeam photodynamic therapy for actinic keratoses. The registry record lists 12 participants, a randomized allocation, no masking, and a single-group model. Arm descriptions vary ALA application time and laser conditions. The primary outcome concerns PpIX accumulation in relation to skin preparation, ALA application time, and body site.
The record reports that treatment assignments and outcomes were entered by the principal investigator’s staff before centralized data management was introduced, were later lost, and could not be retrieved. It lists seven outcome measures and no analyses. No primary-outcome values, effect estimates, confidence intervals, or test results are reported. The record therefore documents the intended question and the data-loss limitation, but does not provide results with which to assess the treatment conditions.