Blinded Study of Topical Investigational Lotion Vs. Approved Cream in Treatment of Plaque Psoriasis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Blinded Study of Topical Investigational Lotion Vs. Approved Cream in Treatment of Plaque Psoriasis (NCT01166646), a randomized phase 2 study. The primary outcome is Adrenal Suppression Potential.

2. Clinical Question

These descriptions point to related but distinct questions. The brief summary concerns treatment effectiveness for plaque psoriasis, whereas the primary outcome measures a hormonal response at the end of treatment. The secondary outcome names refer to disease severity and signs of psoriasis, but the registry record does not report their comparative results. Therefore, the registered outcome hierarchy does not support treating the adrenal-suppression measure as a direct measure of psoriasis improvement. Nor does the stated purpose alone establish whether the lotion and cream differed on effectiveness or on the primary outcome.

3. Trial Design

This was a randomized, single-masked, parallel-group Phase 2 study of two topical treatments for plaque psoriasis. Participants were assigned to Halobetasol Proprionate Lotion 0.05% or Halobetasol Proprionate Cream 0.05%. The record describes the lotion arm as participants randomized to receive lotion and the cream arm as participants randomized to receive cream. Total enrollment was 43.

The study status is completed. The registry record lists a start date of 2010-07 and primary completion in 2011-07. These dates describe the trial’s timing but do not supply details about the duration of follow-up for every outcome or participant. The primary outcome timeframe is stated as “After 1-2 weeks dose.” The record does not report further detail about the exact assessment schedule or the amount of treatment received by each participant.

Random allocation supports a comparison of assigned groups by reducing the risk that assignment is systematically determined by participant characteristics. In general, masking can reduce the influence of knowledge about treatment assignment on care, assessment, or reporting, but the record labels masking only as single and does not specify who was masked. The parallel-group structure means the registry describes separate groups receiving the lotion or the cream, rather than a crossover sequence.

The trial includes six outcome measures, but the record does not provide analysis results for the primary outcome. It also lists no analyses. The enrollment count should therefore not be mistaken for a count of participants with complete outcome data, nor does it establish how many were included in a particular outcome analysis. The record defines the primary-outcome population as randomized participants who applied at least one dose, but does not report arm-specific denominators for that outcome or explain how missing observations were handled.

The trial’s stated objective was to determine whether the investigational lotion was an effective treatment compared with an approved cream. The design also included an adrenal response outcome and secondary outcomes relating to psoriasis signs and severity. The distinction matters: design features describe how a comparison was organized, while outcome estimates are needed to determine what the posted data show about that comparison.

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: All subjects who met the entry criteria were randomized and enrolled into the study.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Analysis shown is based on the ITT population, defined as all enrolled participants who were randomized and applied at least one dose of the test article.

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: The Intent-To-Treat (ITT) population included all participants enrolled in the study who were dispensed and applied test article at least once and had at least one follow-up visit after the Baseline visit (Visit 2). All 43 enrolled subjects were included in the ITT population.

6. Primary Endpoint

The registry lists the primary outcome as Adrenal Suppression Potential, measured over After 1-2 weeks dose.

The primary outcome is titled “Adrenal Suppression Potential.” It counts participants, and the registry describes the underlying result as a number. The assessment uses Hypothalamic Pituitary-Adrenal (HPA)-Axis responses to Cosyntropin Stimulation Testing (CST). Responses are dichotomized into normal and abnormal categories. An abnormal response, termed HPA suppression in the record, is defined as a 30-minute post-stimulation serum cortisol level of ≤18 μg/dL at the end of treatment. The stated timeframe is “After 1-2 weeks dose.”

A binary endpoint turns a measured response into categories, making it possible to count participants meeting a prespecified definition rather than comparing the full range of cortisol values. In general, a threshold can make an outcome straightforward to interpret as the presence or absence of the defined event. It also discards information about how far an individual measurement lies from the threshold, so the event count does not describe the distribution of all cortisol results.

This endpoint is used to assess adrenal suppression potential, not to measure psoriasis severity directly. The brief study purpose concerns treatment effectiveness, and the secondary outcomes mention disease severity and psoriasis signs designated “Success.” Those are separate clinical questions. The registry record does not report a primary-outcome event count by arm or a comparative estimate, so the endpoint definition alone cannot establish how the groups differed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a binary endpoint represent?

The primary outcome is recorded as a number of participants and is based on a binary classification: normal or abnormal HPA-Axis response. The abnormal category is defined using the specified 30-minute post-stimulation serum cortisol threshold at the end of treatment. A binary outcome is useful when the research question concerns whether participants meet a defined event criterion. It gives an event count for each group, if those counts are reported.

In general, converting a continuous measurement into two categories simplifies interpretation, but it removes information about variation within each category. Participants just on either side of a threshold are assigned different labels even when their measurements may be close. Conversely, participants with quite different values can share the same category. The event definition must therefore be considered alongside the reported result. Here, the registry states the threshold, but does not provide the group-specific primary endpoint counts or a comparative estimate.

What does randomization contribute?

Randomization assigns participants to groups by chance. In general, this helps reduce systematic differences between treatment groups at the point of assignment, so that a later group comparison can be interpreted as an estimate of the effect of assignment under the trial conditions. Randomization does not guarantee that groups will be identical, especially in a relatively small trial, and it does not resolve problems from missing outcome data or incomplete reporting.

This study is identified as randomized, single-masked, and parallel. The record does not state who was masked, how the random sequence was generated, or how allocation was concealed. Those specific design details are not reported in the registry record. The analysis population is described for the primary outcome as all enrolled participants who were randomized and applied at least one dose of the test article. This definition is relevant to interpreting any outcome count, but arm-specific numbers included in that population are not reported.

How should group comparisons be read?

For a binary outcome, a comparison can be expressed using event counts and denominators, together with an effect estimate on a stated scale. In general, risk differences, risk ratios, or odds ratios answer related but distinct questions. A confidence interval expresses the statistical uncertainty around an estimate under the assumptions of the chosen method. A p-value, when reported, addresses compatibility between the observed data and a specified null hypothesis; it does not measure the size or clinical importance of an effect.

The registry record does not provide a primary endpoint contrast, p-value, or confidence interval. Because the outcome is described as having several categories or time points and was not reduced to one comparison, a single primary comparison cannot be recovered from the registry information. No statistical method for a primary-outcome comparison is reported in the registry record. It would be inappropriate to select a method and treat the resulting analysis as the sponsor’s reported analysis.

What do the sample-size assumptions mean?

General sample-size planning estimates depend on assumptions about the effect to detect, the significance level, allocation, and the statistical approximation. The stated planning assumptions describe a two-sided significance level of 0.05, equal allocation, a normal approximation, and effects defined as fractions of the observed effect. They are described as planning illustrations based on an observed effect, not as the trial’s own design justification. The registry record does not report the protocol’s sample-size justification.

A planning illustration is not observed power. It does not show the probability that the completed trial established a treatment effect, and it cannot substitute for an effect estimate with uncertainty. The stated approach gives participants per arm for non-time-to-event outcomes; time-to-event calculations instead concern total events. The registry record does not report a primary comparison from which to assess such a planning illustration for this endpoint, nor does it report the specific planning results in the information available for interpretation.

Why does over-dispersion matter in general?

Over-dispersion is a general issue for count models when observed variability exceeds what a chosen model expects. If over-dispersion is ignored, standard errors can be too small and confidence intervals too narrow. This trial’s primary outcome is a count of participants meeting a binary criterion, not a reported rate of recurrent events. The registry record does not report a count-model analysis or identify over-dispersion as an analysis issue for this endpoint. The concept is therefore general context, not a description of a method used in this trial.

What can be concluded from the posted analysis information?

The registry lists zero analyses and does not provide a primary-outcome comparison. The endpoint definition and the group assignment structure are reported, but statistical interpretation requires outcome data and an analysis specification. In their absence, no effect estimate can be reconstructed without making choices or calculations that are not part of the reported analysis. The serious and other adverse-event counts can be described as counts, but the registry does not give a statistical comparison for those data either.

10. Multiplicity, Missing Data and Analysis Populations

The record lists six outcome measures, including the primary outcome of adrenal suppression potential and secondary outcomes concerning changes in disease severity and psoriasis signs designated “Success.” It also notes that the primary outcome has several categories or time points and was not reduced to one comparison. This makes it difficult to identify a single reported primary contrast or to determine how results across categories and time points were handled.

Multiplicity is a general statistical concern when several outcomes, comparisons, or assessment times are examined. Multiple opportunities to test hypotheses can increase the chance of observing a nominally notable result by chance. In general, analysis plans may address this through prespecified outcome hierarchies or adjusted inference. The registry record does not report whether any multiplicity adjustment or other strategy was planned or used.

The registry defines the primary outcome population as all enrolled participants who were randomized and applied at least one dose of the test article. This is the only explicit primary-outcome population definition reported. The record does not report the number analyzed in each arm for this endpoint, the amount of missing outcome data, or the method used to handle missing observations. It also does not report whether secondary outcomes used the same population.

The record lists zero analyses and does not report a primary result. Therefore, it is not possible to assess adherence to a statistical analysis plan, determine how missingness affected estimates, or establish whether all planned outcomes were reported. Details of any protocol-level analysis plan are not reported in the registry record. These gaps limit both the interpretation of multiplicity and the evaluation of the primary analysis population.

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 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports zero serious adverse events among 21 participants at risk in the Halobetasol Proprionate Lotion 0.05% group, and zero among 22 participants at risk in the Halobetasol Proprionate Cream 0.05% group. These are the serious-event counts in the record. They do not by themselves establish that the treatments have equivalent safety profiles or that serious events are impossible.

For other adverse events, the record reports 9 affected participants among 21 at risk in the lotion group and 8 among 22 at risk in the cream group. These counts are separate from the serious adverse-event counts. The registry describes these figures as numbers of participants with an event; it does not provide event-level descriptions in the material available for interpretation, nor a comparative statistical analysis or confidence interval. The counts should not be treated as evidence of a difference between groups without an appropriate estimate and its uncertainty.

The deaths field is not reported in the registry record, so it should not be read as a zero count. The record also does not provide details about event timing, severity beyond the serious-event classification, or causal attribution. These figures are a descriptive account of reported adverse events, not a complete assessment of all potential harms.

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

The registry record establishes that a randomized, single-masked, parallel-group Phase 2 study compared Halobetasol Proprionate Lotion 0.05% with Halobetasol Proprionate Cream 0.05% in plaque psoriasis. It specifies a primary endpoint based on a binary HPA-Axis response to Cosyntropin Stimulation Testing and identifies secondary outcomes concerning psoriasis severity and signs. It also reports adverse-event counts for the two groups.

Those details describe the trial and its recorded outcomes, but they do not answer the central comparative questions. A primary-outcome result is not reported in the registry record, and the record lists zero analyses. It therefore does not show the magnitude or direction of a group difference in adrenal suppression potential. The outcome names for disease severity and psoriasis signs likewise do not establish whether the groups differed on those measures.

In general, a well-reported treatment comparison includes an estimate on a clear scale, the number of participants contributing data, and a measure of uncertainty. Without those elements for the primary outcome, a reader cannot determine how precisely any difference was estimated or distinguish a small, uncertain difference from a larger one. The lack of a reported estimate must not be interpreted as a finding of no difference.

The adverse-event counts indicate the number of affected participants reported in each group, including zero serious events in each. They do not establish equivalence, rule out uncommon events, or provide a causal assessment. The deaths field is not reported in the registry record. The counts also do not replace the missing primary-outcome analysis or provide evidence about psoriasis effectiveness.

The study’s completed status and total enrollment do not change these limits. The posted information supports a description of the study design, endpoint definition, and recorded adverse-event counts. It does not support a conclusion that one treatment is more effective or safer than the other, and it does not support a conclusion of equal effects.

13. Why This Trial Matters Statistically

This trial illustrates why the stated study objective, the registered primary outcome, and the reported results need to be read separately. The brief summary frames the study as a comparison of effectiveness for moderate to severe plaque psoriasis. Its primary outcome, however, is adrenal suppression potential, while the secondary outcome names concern disease severity and psoriasis signs. Each addresses a different aspect of the treatment comparison.

That distinction is important in biostatistics because a result on one endpoint cannot automatically answer a different clinical question. A binary adrenal response can be relevant to a trial’s assessment of treatment, but it is not itself a direct measure of improvement in psoriasis signs. Similarly, an outcome label such as “Success” does not tell readers how success was defined, how many participants met that definition, or how the groups compared.

The record also shows how incomplete analysis reporting restricts inference. It gives the endpoint definition and identifies the ITT population but provides no comparative primary result and lists zero analyses. Consequently, readers cannot evaluate effect size, precision, or the statistical handling of multiple outcome categories or time points. The registry’s note that the primary outcome was not reduced to one comparison further limits interpretation.

The adverse-event counts offer a separate example of descriptive versus comparative evidence. Counts are useful for understanding what was recorded, but without a comparative estimate and uncertainty they do not establish a difference or equivalence. The trial’s enrollment and completion status cannot replace those missing analyses. Statistically, the central lesson is that design information can clarify what a study sought to examine, while transparent outcome reporting is required to judge what the data support.

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 main trial-specific limitation for interpretation is that no comparative result for the registered primary endpoint is reported in the registry record. Although the outcome definition and timeframe are described, group-specific endpoint counts, an effect estimate, and uncertainty measures are not reported. The record also lists zero analyses, preventing assessment of the statistical approach used for the primary comparison.

The registry notes that the primary outcome has several categories or time points and was not reduced to one comparison. It does not explain how those categories or assessment times were handled, whether a particular comparison was prespecified, or whether multiplicity was addressed. The record lists six outcome measures, but does not provide comparative results for the secondary psoriasis outcomes. The endpoint titles alone cannot fill that gap.

The analysis population is defined as randomized participants who applied at least one dose, but arm-specific analysis denominators and missing-data handling are not reported. The record does not state whether all randomized participants contributed primary-outcome data or how incomplete assessments were treated. Other methodological details, including sequence generation, allocation concealment, the identity of masked parties, and the protocol’s sample-size justification, are not reported in the registry record.

The adverse-event information is limited to group counts for serious and other events. The deaths field is not reported in the registry record, and the information does not give a comparative analysis, event-level detail, or uncertainty estimates. The total enrollment of 43 also means that the reported counts come from relatively small groups; in general, limited group sizes can leave estimates imprecise, particularly for infrequent events.

These limitations do not show that the trial was conducted improperly. They describe what cannot be evaluated from the registry information: the size and precision of the primary comparison, the handling of missing data and multiplicity, and the details of the analysis plan.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Blinded Study of Topical Investigational Lotion Vs. Approved Cream in Treatment of Plaque Psoriasis — NCT01166646.
• Registry record last updated 2016-05-16; status last verified 2016-04.
• Results first posted 2016-05-16.
• 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

This completed Phase 2 study was randomized, single-masked, and parallel-group, with 43 participants enrolled. It compared Halobetasol Proprionate Lotion 0.05% with Halobetasol Proprionate Cream 0.05% for plaque psoriasis. The stated primary endpoint was adrenal suppression potential, defined using a binary HPA-Axis response to Cosyntropin Stimulation Testing after “1-2 weeks dose.”

The registry record defines the primary-outcome population as randomized participants who applied at least one dose. It lists six outcome measures and zero analyses. A comparative result for the primary endpoint and results for the named psoriasis secondary outcomes are not reported in the registry record. The record notes multiple categories or time points for the primary outcome, not reduced to one comparison.

Serious adverse events were reported for zero participants in each group; other adverse events were reported for 9 participants in the lotion group and 8 in the cream group. The deaths field is not reported. The registry information describes the design and some event counts but does not establish comparative effectiveness, safety, or equivalence.