Hexaminolevulinate (HAL) Photodynamic Therapy (PDT) of Cervical Intraepithelial Neoplasia (CIN) Grade 1: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Hexaminolevulinate (HAL) Photodynamic Therapy (PDT) of Cervical Intraepithelial Neoplasia (CIN) Grade 1 (NCT00708942), a randomized phase 2 study. The primary outcome is Complete Response Rate.

2. Clinical Question

3. Trial Design

The registry record describes a randomized, phase II, parallel-group study with quadruple masking. It lists enrollment as 83 and gives the study status as terminated. The recorded start is 2009-01, and the primary completion date is 2012-01. The reason for termination and the timing or circumstances of that decision are not reported in the registry record.

There are five arm descriptions. Arm 1 used a single HAL 100mg suppository administration followed by laser illumination at 50J/cm2. Arm 2 used a single placebo suppository administration followed by laser illumination at 50J/cm2. Arm 3 is listed as no intervention. Arm 4 used a single HAL ointment administration, described as 5% and 100mg, followed by LED diode illumination at 50J/cm2. Arm 5 used a single placebo ointment administration without illumination.

These arms vary in formulation, illumination and whether an intervention was given. Consequently, an arm-specific response percentage should not be treated as if it came from a single common comparison. The record identifies OG001, the placebo suppository with laser illumination, as the control, but it also posts results for other arms. The registry record does not report the allocation ratio, the detailed randomization procedure, or how masking was implemented for each treatment approach.

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.

Before assignment: Recruitment to part 1, including arms 1-3, completed before initiation of part 2 (arms 4-5). Arms 4 and 5 was a protocol amendment.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Per protocol population. Patients with major protocol violations excluded.

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 Complete Response Rate, measured over 6 month.

The primary endpoint was Complete Response Rate at 6 month, expressed as the percentage of patients analyzed. Complete response required normal pathology, normal cytology and negative HPV. It is therefore a combined endpoint: a patient had to meet all three stated conditions to count as a complete response. A normal result in only one or two components would not meet the registry definition.

Combining these measures can describe response across tissue findings, cytology and HPV status in one outcome. It also means the overall percentage does not show which component drove the response classification. The registry record does not provide component-specific primary results or further operational definitions for the individual tests.

The stated analysis population was per protocol, excluding patients with major protocol violations. The posted arm-specific percentages are 57.1% for HAL suppository with laser illumination, 40.0% for placebo suppository with laser illumination, 0.0% for no intervention, 90.0% for HAL ointment with LED diode illumination, and 33.3% for placebo ointment without illumination. The record lists the corresponding arm counts, but it does not report confidence intervals for these endpoint values. Without an interval or an estimable comparison, the percentages alone do not convey the precision of a treatment effect.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation starts with the outcome definition and the analysis population. The primary outcome is a proportion: the fraction of analyzed patients classified as complete responders under the stated combined criteria. The registry expresses it as a percentage of patients analyzed and identifies a per protocol population, excluding patients with major protocol violations. The record does not give more detail about the calculation procedure or any adjustments.

What does an arm-specific percentage describe?

An arm-specific percentage describes the observed share of the analyzed group that met the response definition. It is useful as a descriptive summary, but it does not by itself compare treatment groups. A comparative treatment analysis normally estimates a contrast between specified arms and quantifies uncertainty around that contrast. The registry record does not report an estimable two-arm comparison for this endpoint, and the analysis count is zero. The posted percentages should therefore be read as separate arm descriptions, not as a sponsor-reported treatment effect.

There are several distinct possible comparisons in this study because the arms differ in formulation, illumination and comparator. HAL suppository with laser illumination can be described alongside placebo suppository with laser illumination. HAL ointment with LED diode illumination can be described alongside placebo ointment without illumination. The record also lists no intervention. These are not interchangeable contrasts: a difference between two arms could reflect more than the active substance if other aspects of the treatment approach also differ. No single comparison spanning all five arms is reported as estimable.

Why does precision matter?

General statistical explanation: a confidence interval gives a range of values compatible with the observed data and the method used to analyze them. It communicates uncertainty in a way that a point estimate alone cannot. A narrow interval indicates greater precision under the stated method; a wide interval indicates less precision. No confidence intervals for the primary arm-specific percentages are reported in the registry record, so their precision cannot be judged from posted intervals. The arm counts are also not equal, and some are limited, making it especially important not to interpret the percentages without uncertainty information.

A p-value, when reported, addresses how compatible data are with a specified statistical model and null hypothesis. It does not measure the probability that a treatment works, nor does it indicate the size or clinical importance of an effect. No primary comparative p-value is reported in the registry record. The absence of a reported test is not equivalent to a test showing no difference; it means the record does not provide that inferential result.

What does the per protocol population imply?

General statistical explanation: a per protocol analysis focuses on participants who met protocol requirements, while an analysis of all randomized participants addresses a different question and preserves the original randomized group assignment. Excluding participants after randomization can affect comparability if exclusions are related to treatment, outcome or prognosis. Here, the registry states that patients with major protocol violations were excluded from the primary analysis, but does not report how many were excluded, why, or whether an intention-to-treat analysis was also performed. Those details are needed to assess the potential impact of the analysis population.

How should planning calculations be read?

The stated planning assumptions describe illustrations based on the observed effect, not the trial's original design or observed power. They specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the target effect is expressed as a fraction of the observed effect. For outcomes other than time-to-event outcomes, such illustrations are stated in participants per arm for 80% power or another stated power level. Time-to-event illustrations use total events. Such calculations are hypothetical planning aids: they do not tell whether the completed trial had adequate power, and they are not evidence that an effect was detected. The registry record does not report the trial's own sample-size justification or design assumptions.

The endpoint is recorded as count other, and the registry notes that values are missing or not estimable for a two-arm comparison. No new comparative calculation can repair that reporting gap without making additional assumptions. Any simple re-calculation from arm summaries would be unadjusted and should not be confused with the sponsor's analysis. Since no discrepancy is recorded and no sponsor comparative analysis is posted, the arm summaries remain the appropriate description of what is available.

What information is absent?

The registry record does not report the statistical model, covariates, confidence interval method, handling of missing endpoint measurements, or details of any sensitivity analysis. It also does not provide a comparative estimate for the primary endpoint. These omissions prevent readers from reproducing an inferential analysis or evaluating the robustness of a treatment contrast. General principle: conclusions about treatment differences depend not only on observed percentages but also on the prespecified comparison, analysis population, model and uncertainty estimates.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists two secondary outcomes: eradication of HPV and incidence of patients with adverse events. It also lists three outcome measures, but reports no analyses. The record does not state whether the primary and secondary outcomes were tested in a hierarchy, whether any multiplicity adjustment was planned, or whether the secondary outcomes were considered exploratory. It is therefore not possible to determine how the chance of false-positive findings across multiple outcomes was handled.

For the primary endpoint, the record specifies a per protocol population and exclusion of patients with major protocol violations. It does not report the number excluded, the reasons for exclusion, or how missing pathology, cytology or HPV measurements were treated. The registry record does not report whether missing components were counted as non-response, excluded from the denominator, imputed, or handled in another way. Those details matter because complete response requires all stated components to be normal or negative.

The record also does not report an intention-to-treat analysis, sensitivity analyses for missing data, or an account of participants who did not contribute to the endpoint. No assumptions about missingness or protocol deviations can be inferred from the posted percentages. The registry's stated per protocol definition should therefore be kept distinct from the broader randomized study population when interpreting the results.

11. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 4% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: depression (9.1%), jaw fracture (2.1%), schizophrenia (2.1%), concomitant disease aggravated (2.1%).

The safety record reports serious adverse events and other adverse events separately, with counts of participants at risk and affected in each arm. For serious adverse events, the reported affected counts are 3 among 47 at risk in the HAL suppository with laser arm, 0 among 12 in the placebo suppository with laser arm, 1 among 11 in the no-intervention arm, 0 among 10 in the HAL ointment with LED diode illumination arm, and 0 among 3 in the placebo ointment without illumination arm. These are the registry's arm-specific counts; they should not be combined across arms to create a new overall total.

The record lists Depression at 9.1%, Jaw fracture at 2.1%, Schizophrenia at 2.1%, and Concomitant disease aggravated at 2.1% among the top serious terms. The record does not explain the denominator or event attribution for these term percentages, so they should be read as registry-listed terms rather than as treatment-specific risks. Death counts are not reported in the registry record.

General statistical explanation: adverse-event counts describe events recorded during the study and do not, without further analysis, show that an intervention caused them. Differences in counts across arms also need to be interpreted in light of the numbers at risk and the distinct arm conditions. The registry record does not provide a causal safety comparison.

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

The posted results establish that the registry recorded complete response percentages for each arm at 6 month, using a definition that combines pathology, cytology and HPV status. The values range across distinct treatment conditions, with different arm counts. They offer descriptive information about the outcomes recorded in this study, but the registry does not provide an estimable two-arm primary comparison or an uncertainty interval for those percentages.

Accordingly, the values do not establish the size or precision of a HAL-versus-control effect. They do not show whether a difference between any two arms is statistically distinguishable from chance, and they should not be used to claim that a treatment works or does not work. The study includes different formulations and illumination conditions, so the results do not represent one uniform HAL intervention compared with one uniform control.

The primary endpoint was assessed in a per protocol population that excluded patients with major protocol violations. Without the number and reasons for exclusions, the missing-data approach and an intention-to-treat analysis, the effect of those analysis choices cannot be evaluated. The record's terminated status is also not accompanied by a reason and does not itself explain the results.

The appropriate interpretation is limited to what is posted: arm-specific response summaries and safety counts, alongside important gaps in comparative and uncertainty reporting. These results are not a substitute for a reported treatment contrast with its analysis population and precision. They also do not answer questions beyond the study's stated population, endpoint, treatment conditions and follow-up timeframe.

13. Why This Trial Matters Statistically

This study illustrates why the design of a comparison matters as much as the observed response percentages. The five arms do not differ only by whether HAL was used: the formulation, illumination approach and presence of an intervention vary. A comparison between HAL suppository and placebo suppository shares the laser illumination condition, whereas the ointment arms differ in both active ingredient and illumination status. The registry also includes a no-intervention arm. Keeping those contrasts distinct is essential to avoid attributing every difference to HAL alone.

It also demonstrates the difference between descriptive outcome reporting and inferential evidence. The registry gives arm-specific percentages and counts, but no estimable two-arm comparison, confidence interval or primary comparative p-value. Without a comparative estimate and a measure of uncertainty, the posted values cannot show how precisely a treatment contrast is known. A point percentage can appear quite different from another while still leaving uncertainty about the underlying contrast.

The per protocol endpoint definition raises a further statistical issue: reported results depend on who is included in the analysis. Excluding patients with major protocol violations may be relevant to the study question, but assessment requires details about exclusions and missing outcomes. Those details are not reported in the registry record.

Finally, the record distinguishes a study's status from its statistical findings. The study is listed as terminated, but the reason is not reported. Neither the status nor the descriptive results supply a missing comparative analysis. Together, these features make the study a useful example of how arm structure, analysis population and precision reporting shape what can responsibly be concluded from a clinical trial record.

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 primary endpoint results are reported as arm-specific percentages without confidence intervals or a sponsor-reported comparative estimate. The registry specifically indicates that values are missing or not estimable for a two-arm comparison, and it lists zero analyses. This prevents assessment of a treatment contrast using the inferential results of the trial.

The arm conditions are heterogeneous. The HAL suppository and placebo suppository both include laser illumination, while the HAL ointment uses LED diode illumination and the placebo ointment has no illumination. A no-intervention arm is also listed. The results therefore cannot be interpreted as a simple comparison of one consistent HAL regimen against one consistent control regimen.

The primary analysis is per protocol and excludes patients with major protocol violations, but the registry record does not report the number excluded, the reasons, or how missing outcome components were handled. This matters because all components of the complete-response definition must be met. There is no reported intention-to-treat analysis or sensitivity analysis to show how alternative analysis choices might affect the results.

Further limitations include the absence of a reported statistical model, confidence-interval method, multiplicity approach and trial-specific sample-size justification. The registry lists the trial as terminated without reporting the reason. These gaps constrain interpretation of both the effectiveness endpoint and the safety summaries. The posted adverse-event counts also do not, by themselves, establish that events were caused by a study treatment.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Hexaminolevulinate (HAL) Photodynamic Therapy (PDT) of Cervical Intraepithelial Neoplasia (CIN) Grade 1 — NCT00708942.
• Registry record last updated 2013-04-24; status last verified 2013-04.
• Results first posted 2013-04-15.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry record describes a randomized, quadruple-masked, parallel-group phase II study of HAL photodynamic therapy for low-grade cervical intraepithelial neoplasia. It lists enrollment as 83, a start of 2009-01, primary completion at 2012-01, and status as terminated. The reason for termination is not reported in the registry record.

The primary endpoint was complete response at 6 month in a per protocol population, defined by normal pathology, normal cytology and negative HPV. Five arm-specific response values are posted, but the record reports no analyses and no estimable two-arm comparison. It also lists HPV eradication and adverse events as secondary outcomes. Comparative uncertainty estimates, missing-data details and the trial's own sample-size justification are not reported in the registry record.