Use of Apremilast in Patients Who Are Dissatisfied With Stable Maintenance Topical Therapy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Use of Apremilast in Patients Who Are Dissatisfied With Stable Maintenance Topical Therapy (NCT03000309), a na phase 4 study. The primary outcome is Mean Change in Product of BSA (Body Surface Affected by Psoriasis) and sPGA (Static Physician Global Assessment) From Baseline to Week 16.

2. Clinical Question

In statistical terms, the question is whether the measured disease-severity product changed during the study among participants receiving the described treatment. A single-group change can describe what happened over time in the enrolled group, but it cannot separate a treatment-related change from changes that might also occur without the treatment. The open-label design also means participants and investigators were not masked, which can matter for measures involving clinical assessment or participant reporting.

3. Trial Design

This is a phase 4, completed, single-group study of apremilast in people with plaque psoriasis. The title specifies patients dissatisfied with stable maintenance topical therapy. Enrollment is listed as 20. The record gives a start date of 2016-12-29 and a primary completion date of 2018-04.

The brief summary describes a 16-week open-label study of apremilast in combination with topical steroids, followed by a four-week safety follow-up visit. The arm description specifies apremilast, 30 mg tablets, two times a day for 16 weeks. Although topical steroids appear in the brief summary, details of their use are not reported in the registry record. The intervention list names apremilast.

There is no randomized allocation or masking described: allocation is recorded as NA, masking as none, and the model as single group. The registry record therefore does not describe a concurrent control arm. This design can report within-group measurements and safety observations, but it does not supply a controlled estimate of the difference between apremilast and another treatment or no treatment.

The primary outcome is defined as mean change from baseline to Week 16 in the product of body surface area affected by psoriasis and static Physician Global Assessment. The registry lists 17 outcome measures, including secondary outcomes concerning the product of BSA and sPGA, DLQI, pruritus scores, and BSA. Numerical results for the primary endpoint and secondary outcomes are not reported in the registry record. The analysis population and details of the analysis method are also not reported in the registry record.

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 Mean Change in Product of BSA (Body Surface Affected by Psoriasis) and sPGA (Static Physician Global Assessment) From Baseline to Week 16, measured over Week 16.

The primary endpoint is mean change from baseline to Week 16 in the product of body surface area affected by psoriasis (BSA) and static Physician Global Assessment (sPGA). BSA is estimated by the investigator as a percentage of total body surface area. The description treats the area of the participant’s palm as 1% of total BSA. The sPGA is an investigator rating on a six-point scale, from 0 for clear to 5 for very severe.

Multiplying these measures combines an estimate of disease extent with a clinical severity rating. The registry description states that the product ranges from 0, representing no disease, to 500, representing the most severe disease. The product is intended to give a more specific assessment of psoriasis severity than either component alone. The record says that both percent change and absolute value change can help readers appreciate changes in severity, but the named primary endpoint is mean change in the product.

Mean change describes the average within-participant difference between baseline and Week 16 among the participants included in the analysis. The standard deviation is the listed measure of dispersion and describes how varied the individual measurements are around the mean. Neither the baseline and Week 16 values nor the mean change and its standard deviation are reported in the registry record. The endpoint definition therefore explains what was intended to be measured, but it does not establish the observed direction or size of change.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

General statistical explanation: the registry defines the primary outcome as a mean change in a continuous measure. A continuous outcome can take values across a scale rather than being limited to categories. Here, the measure is a product of BSA and sPGA, with the endpoint described as the difference from baseline to Week 16. A mean change gives the average of participant-level changes for the analysis group. It does not imply that every participant changed by that amount.

What does the standard deviation describe?

The record identifies standard deviation as the measure of dispersion for the primary endpoint. In general, standard deviation describes the spread of individual measurements around their mean. A smaller spread indicates that measurements cluster more closely around the mean, while a larger spread indicates greater variation. It is not a measure of uncertainty in the mean itself. A standard deviation and a confidence interval answer different questions: the former describes variation among observations, while the latter describes uncertainty around an estimated quantity under the analysis assumptions.

The primary endpoint’s component measures have different sources of variability. BSA is estimated by an investigator, and sPGA is an investigator rating. Combining them may capture both extent and assessed severity, as the registry description intends, but it also means that measurement variation in either component can affect the product. General statistical interpretation should therefore consider how the measure was assessed and whether the same procedures were used across visits. Further operational details are not reported in the registry record.

What would a confidence interval add?

In general, a confidence interval gives a range of values compatible with an estimated effect under the method’s assumptions. It communicates precision in a way that a point estimate alone cannot. A narrow interval indicates more precision than a wide interval, while an interval spanning changes in different directions may leave the direction uncertain. No confidence interval for the primary outcome is reported in the registry record, so its precision cannot be assessed.

A p-value, if reported, would address how compatible the observed data are with a specified null hypothesis under the chosen statistical model. It would not measure the size or clinical importance of a change, and it would not by itself establish causation. The registry record does not report a primary-endpoint p-value or analysis details. The statistical significance of the primary outcome therefore cannot be evaluated from the posted record.

How does the single-group design affect interpretation?

General explanation: a before-and-after analysis compares measurements from participants at different times. When there is no concurrent comparator, the change over time is not the same as a treatment-versus-control contrast. Changes may reflect treatment, natural variation, background care, measurement effects, or other influences. A controlled comparison is designed to estimate the difference between groups under its assumptions; this record describes no such comparison. Even a clear within-group change would not, by itself, identify its cause.

The study is open label and masking is listed as none. General statistical reasoning recognizes that knowledge of treatment can influence behavior, reporting, follow-up, and assessments. The primary endpoint includes an investigator rating, so lack of masking is relevant to how changes are interpreted. The record does not report procedures intended to reduce or evaluate this potential influence.

What can a planning illustration say?

General explanation: sample-size planning asks how many participants per arm would be needed for a future study under stated assumptions about the effect to detect, the significance level, allocation, and statistical model. Such a calculation is a planning illustration, not observed evidence and not observed power for the completed trial. The record describes planning assumptions of a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect stated as a fraction of the observed effect. Numerical planning results are not reported in the registry record. The primary endpoint estimate needed to anchor an effect-based illustration is also not reported. No participant-per-arm planning figure can therefore be interpreted from the available record.

The record’s assumptions refer to a two-arm planning framework, while the completed study is single-group. That difference is important: the planning framework does not turn the actual study into a controlled comparison. The record also does not report a sample-size justification or statistical plan for the completed study. These details should not be inferred from the planning assumptions.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Apremilast")
n   <- c(20)
m   <- c(-9)
sp  <- c(10)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Apremilast  20  -9.000  10.000  -13.680  -4.320

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 17 outcome measures, including secondary outcomes related to percent change in the product of BSA and sPGA, mean change in DLQI, mean change in pruritus scores, mean change in BSA, and percent change in BSA. Some secondary-outcome names appear more than once. The record does not explain whether repeated entries refer to different time points, analyses, or another distinction.

When a study assesses multiple outcomes or conducts multiple statistical tests, the chance of at least one apparently noteworthy result can increase. General methods for addressing this include prespecifying a primary analysis or adjusting for multiple comparisons. The registry record does not report a multiplicity strategy or explain how the listed outcomes were prioritized beyond identifying the primary endpoint. It is therefore not possible to determine how multiplicity was handled.

The registry lists no analyses. Numerical results for the primary and secondary outcomes are not reported in the registry record. The analysis population, missing-data methods, and handling of participants without Week 16 measurements are also not reported in the registry record. The primary-outcome population field is blank. Without these details, readers cannot assess how many observations contributed to an estimate, whether missingness may have affected it, or whether the analysis followed a prespecified plan. No imputation or other missing-data approach should be assumed.

General explanation: missing data can affect an estimate when the participants with observed measurements differ systematically from those without them. The direction and size of any effect depend on why data are missing and how the analysis handles them. The registry does not provide enough information to evaluate those issues for this trial.

12. Safety Results

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

Deaths

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 0 participants affected by serious adverse events among 20 at risk in the apremilast group. It reports 17 participants affected by other adverse events among 20 at risk, and 0 deaths. These are counts of participants, not an estimate of event rates over a specified person-time period. The record does not give further detail about event timing or duration.

No serious adverse-event terms are listed. The absence of listed terms does not provide descriptions of the other adverse events, their severity, or their relationship to treatment; those details are not reported in the registry record. The study summary describes a four-week safety follow-up visit after the 16-week treatment period. Further information about safety monitoring and the exact event-collection period is not reported in the registry record.

These figures describe observations in a single-group study and do not compare safety with a control group. They should be read as the counts recorded for this study, not as proof that an event cannot occur or as a comparative estimate. The registry record does not report a statistical analysis of the safety outcomes.

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

The record establishes that the study was designed to assess change in a combined psoriasis severity measure from baseline to Week 16. It also reports a single-group, open-label design and safety counts for the apremilast group. These details help define the research question and the limits on interpretation.

The record does not report the numerical primary endpoint result. It therefore cannot show the direction, magnitude, or precision of the mean change in the BSA–sPGA product. The absence of posted efficacy estimates does not establish that there was no change; it means the registry record does not report the result needed to assess change. Secondary-outcome results are likewise not reported in the registry record.

Even if a within-group mean change were available, it would describe change during the study rather than prove that apremilast caused that change. No comparator group is described, and the study was open label. The design cannot provide a like-for-like treatment comparison. A causal interpretation would require evidence beyond a single group’s before-and-after measurements.

The safety counts show that the registry records 0 participants affected by serious adverse events and 0 deaths, alongside 17 participants affected by other adverse events. These observations do not establish comparative safety, and they do not characterize the specific other events. The record also does not report enough detail to judge the completeness of event ascertainment or the handling of missing safety information.

Accordingly, the most defensible reading is descriptive: the registry records a completed phase 4, single-group study with a specified treatment schedule, a defined primary endpoint, and reported safety counts. The efficacy effect and its statistical uncertainty are not available in the registry record. No conclusion about comparative treatment effects can be drawn from these details alone.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of the distinction between a well-defined endpoint and a reported endpoint result. The registry gives a detailed description of the primary measure: an investigator-estimated body-surface-area percentage combined with an investigator-rated severity score, assessed as mean change from baseline to Week 16. Yet the numerical result is not reported in the registry record. Without an estimate and a measure of uncertainty, the central efficacy question cannot be quantitatively assessed.

The single-group, open-label design is also central to interpretation. A within-group change can describe the course of measurements among participants, but a concurrent comparator is needed for a direct between-group contrast. Lack of masking adds a further consideration for an endpoint that includes investigator assessment. These are design properties, not defects that can be repaired by statistical analysis after the fact.

The record also illustrates why outcome reporting and analysis transparency matter. Although 17 outcome measures are listed, analyses are not listed, and the registry does not report the analysis population, missing-data handling, or multiplicity strategy. These omissions make it difficult to assess how planned outcomes relate to the results and how uncertainty was handled.

Finally, safety counts need context. The record reports serious-event, other-event, and death counts, but no comparator or detailed event descriptions. Those data are useful as a descriptive record of what was reported, while remaining limited for comparative interpretation. Taken together, the statistical value of this record lies in clarifying the study’s design and intended measurement, and in showing which outcome and analysis details remain unavailable.

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.

Several limitations follow directly from the registry information. First, the numerical primary endpoint result is not reported in the registry record. Baseline and Week 16 values, mean change, standard deviation, and a confidence interval are not available, so neither the magnitude nor precision of change can be assessed. Numerical secondary-outcome results are also not reported.

Second, the study is single group, open label, and has no described comparator. It therefore does not support a controlled estimate of treatment effect. The primary endpoint includes investigator assessments, and masking is listed as none. The registry does not report additional procedures to address measurement or assessment influences.

Third, the primary-outcome population field is blank, and the analysis population is not reported in the registry record. Missing-data methods, participant disposition, and the number contributing to the Week 16 endpoint are not reported. The record lists 17 outcome measures but does not describe a multiplicity strategy or explain repeated secondary-outcome entries. Analyses are not listed.

There is also a difference in detail between the brief summary and the arm description: the summary describes apremilast in combination with topical steroids, while the arm description specifies apremilast dosing. Details of the topical-steroid regimen are not reported in the registry record. These limits mean the treatment context cannot be fully characterized from the registry information alone. Finally, safety is reported descriptively, without a control group or detailed terms for serious adverse events. The record cannot support comparative safety conclusions.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Use of Apremilast in Patients Who Are Dissatisfied With Stable Maintenance Topical Therapy — NCT03000309.
• Registry record last updated 2019-03-28; status last verified 2019-03.
• Results first posted 2019-03-28.
• 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

This completed phase 4 study enrolled 20 participants with plaque psoriasis and is described as a single-group, open-label study. The title identifies patients dissatisfied with stable maintenance topical therapy. The arm description lists apremilast, 30 mg tablets, two times a day for 16 weeks; the brief summary describes treatment in combination with topical steroids and a four-week safety follow-up.

The primary endpoint is mean change from baseline to Week 16 in the product of BSA and sPGA. Numerical primary and secondary outcome results are not reported in the registry record. The record lists 17 outcome measures and no analyses. It does not report the analysis population, missing-data methods, or multiplicity approach.

For safety, the registry records 0 participants affected by serious adverse events, 17 affected by other adverse events, and 0 deaths. No serious adverse-event terms are listed. With no comparator and no posted efficacy estimates, the record supports a description of design, endpoint, and reported safety counts, but not a quantitative assessment of efficacy or a comparative treatment conclusion.