Evaluate Safety/Efficacy of Two Treatment Regimens for Vectical™ Ointment & Clobex® Spray for Moderate Plaque Psoriasis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluate Safety/Efficacy of Two Treatment Regimens for Vectical™ Ointment & Clobex® Spray for Moderate Plaque Psoriasis (NCT00988637), a randomized phase 4 study. The primary outcome is Number of Participants Who Were a Success (Clear/Almost Clear) of Plaque Psoriasis at Week 4 Based on the Overall Disease Severity (ODS), Full Ordinal Scale From Baseline to Week 4.

2. Clinical Question

The practical contrast is between schedules for using the same two topical treatments, not between a combination regimen and no treatment or a single-treatment control. The registry record describes an open-label study with evaluator blinding: participants and treating personnel were not described as blinded, while outcome evaluators were. The primary endpoint reports a count of participants meeting the clear/almost-clear success category, derived from the Overall Disease Severity scale.

The posted comparison favored the morning/evening schedule in the observed week-4 success counts, and its unadjusted risk-difference confidence interval did not include zero. This is an estimate from the registry results, not a conclusion that one schedule is clinically preferable. The interval communicates uncertainty about the size of the difference, and the record does not report a prespecified threshold for deciding whether a difference is clinically important. The trial also listed secondary assessments of psoriasis severity, treatable body surface area, quality of life, and treatment-program satisfaction.

3. Trial Design

The registry describes a randomized, parallel-group, evaluator-blinded, open-label phase 4 study. Galderma R&D is listed as sponsor, and the condition is plaque psoriasis. Enrollment is reported as 138. The study status is completed, with a start recorded as 2009-10 and primary completion recorded as 2010-03. The registry describes a four-week treatment period.

Participants were assigned to one of two schedules involving Vectical® ointment and Clobex® spray. In one schedule, Vectical® was used on weekdays and Clobex® on weekends, twice daily. In the other, Clobex® was used in the morning and Vectical® in the evening. The registry does not report the method used to generate the random sequence or how allocation was concealed.

Open-label means that treatment assignment was not masked from participants and the clinical team as described in the registry. Evaluator-blinded means the outcome assessor was intended to be unaware of assignment; details of how that masking was maintained are not reported in the registry record. This distinction matters because assessor awareness can influence subjective severity ratings, while participant and clinician awareness can affect reported experiences and other assessments.

The primary analysis population is identified as intent to treat, with LOCF used for missing observations. The record does not describe the handling of protocol deviations, the number of participants with missing primary-outcome data, or whether all randomized participants contributed observed week-4 data. The original sample-size justification, prespecified analysis plan, and any interim analyses are not reported in the registry record. The registry lists 13 outcome measures, while the detailed posted results include the primary endpoint and some secondary outcomes.

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: Wash-out period up to baseline is 30 days for any steroid containing medication, dovonex, anthralin, tar and/or ultraviolet B (UVB) treatment; 12 weeks for corticosteroids, biologics and/or psoralen + ultraviolet A (PUVA) treatment.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: ITT (Intent to Treat), LOCF (Last Observation Carried Forward)

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 Number of Participants Who Were a Success (Clear/Almost Clear) of Plaque Psoriasis at Week 4 Based on the Overall Disease Severity (ODS), Full Ordinal Scale From Baseline to Week 4, measured over Baseline to Week 4.

The primary endpoint counts participants classified as a success, defined as clear or almost clear plaque psoriasis at week 4, using the Overall Disease Severity (ODS) assessment. ODS is described as an ordinal scale from 0 to 4: 0 is clear, 1 almost clear, 2 mild, 3 moderate, and 4 severe or very severe. Lower scores indicate less disease severity. The reported primary outcome is the number of participants reaching the clear/almost-clear category, rather than a mean change across all ODS categories.

A categorical success endpoint is useful because it expresses the result in terms of reaching a specified clinical state. It is relatively straightforward to interpret as a count, and the between-regimen comparison can be expressed as a risk difference: the difference in the proportions meeting the success definition. The registry describes the primary measure as based on the full ordinal scale, while the success outcome specifically identifies the clear/almost-clear category. The detailed rule for deriving that classification beyond the stated categories is not reported in the registry record.

The primary result applies to the intent-to-treat population with LOCF. LOCF carries a participant’s last recorded observation forward when a later observation is missing. This makes the handling of missing observations part of the outcome definition and can affect the result; the record does not give the amount or pattern of missingness. The endpoint captures status at week 4, not the durability of response after treatment ends.

7. Results Posted in the Registry

• Clobex® Spray (Morning) and Vectical® Ointment (Evening): 41.2% (28/68) versus 20.0% (14/70) on control; risk difference 21.2 percentage points (95% CI 6.2 to 36.2), risk ratio 2.06 (1.19–3.56); unadjusted two-proportion z-test p = 0.007.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Number of Participants Who Were a Success (Clear/Almost Clear) of Plaque Psoriasis at Week 2 Based on the Overall Disease Severity (ODS), Dichotomized Scale From Baseline to Week 2

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Clobex® Spray (Morning) and Vectical® Ointment (Evening): 20.6% (14/68) versus 12.9% (9/70) on control; risk difference 7.7 percentage points (95% CI -4.7 to 20.1), risk ratio 1.60 (0.74–3.45); unadjusted two-proportion z-test p = 0.223.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Clobex® Spray (Morning) and Vectical® Ointment (Evening) and the control. The interval gives the range of effects that remain compatible with the data.

Mean Change From Baseline Scores for the Koo-Menter Psoriasis Index 12-item Quality of Life Questionnaire (PQOL-12) From Baseline to Week 4

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Clobex® Spray (Morning) and Vectical® Ointment (Evening): mean -27.50 versus -24.80 on control; difference -2.70 (95% CI -11.07 to 5.67), standardized effect d = -0.11; z-test p = 0.527.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Clobex® Spray (Morning) and Vectical® Ointment (Evening) and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes extend beyond the week-4 primary success count. They include an earlier success assessment, global improvement categories, changes in erythema, scaling and plaque elevation, treatable body surface area, psoriasis-related quality of life, and reported ease of following the treatment program. This range can describe different aspects of disease status and participant experience, but it also means the secondary outcomes address distinct questions rather than serving as interchangeable confirmations of the primary endpoint.

The detailed posted secondary results do not form a single uniform pattern that can be treated as an independent replication of the primary comparison. The week-2 success comparison has an interval that includes zero, as does the mean-change comparison for quality of life. These results do not establish that the regimens are equal on those outcomes; they indicate that the posted comparisons do not resolve a difference clearly. The registry lists additional secondary outcomes, but detailed estimates for all listed outcomes are not included in the posted results.

Secondary findings can help assess whether the primary result is accompanied by changes in other measures, and can generate questions for further study. They carry less weight when their analysis strategy and multiplicity handling are not reported. With several outcomes, an isolated small p-value can occur by chance, while a result that does not cross a conventional threshold can still be compatible with a meaningful effect. The record does not report a testing hierarchy or adjustment strategy, so secondary estimates should be read as supportive or exploratory rather than as definitive evidence for or against the primary finding.

The registry’s primary result is a week-4 dichotomized success endpoint. Other outcomes may reflect severity across categories, particular signs, quality of life, or acceptability. Differences in construct and scale mean that agreement is not guaranteed, and disagreement would not automatically invalidate the primary result. Interpretation is strongest when outcome-specific estimates, uncertainty, missing-data handling, and prespecification are considered together.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Number of Participants Who Were a Success (Clear/Almost Clear) of Plaque Psoriasis at Week 2 Based on the Overall Disease Severity (ODS), Dichotomized Scale From Baseline to Week 2
• Number of Participants in Each Category of the Global Assessment of Improvement (GAI) Scale From Baseline to Week 4
• Number of Participants With a Decrease in Signs of Psoriasis (Erythema) Scores From Baseline to Week 4
• Number of Participants With Decrease in Signs of Psoriasis (Scaling) Scores From Baseline to Week 4
• Number of Participants With Decrease in Signs of Psoriasis (Plaque Elevation) Scores From Baseline to Week 4
• Median Percent (%) Change From Baseline in % Treatable BSA (Body Surface Area) From Baseline to Week 4
• Mean Change From Baseline Scores for the Koo-Menter Psoriasis Index 12-item Quality of Life Questionnaire (PQOL-12) From Baseline to Week 4
• Number of Participants Who Responded to the Categories of Possible Answers to the Subject's Satisfaction Survey Question "The Treatment Program Was Easy to Follow" at Week 4

9. Statistical Interpretation

10. Statistical Methods Explained

What does a risk difference describe?

General explanation: A risk difference compares the proportion of participants with an event in one group with the proportion in another. A positive risk difference means the event was more frequent in the group named first in the comparison. A value of zero corresponds to equal observed proportions. Unlike a relative measure, a risk difference stays on the scale of absolute differences in event probability.

For the primary outcome, the event is being classified as clear or almost clear at week 4. The registry reports a risk difference of 0.212 for the morning/evening regimen relative to the weekday/weekend regimen. This is the posted comparison estimate, not a newly calculated value. It is accompanied by a confidence interval from 0.062 to 0.362. The risk ratio and odds ratio are also posted, but the risk difference is often the most direct scale for describing an absolute contrast in success proportions.

How should the confidence interval be read?

General explanation: A confidence interval describes uncertainty in an estimate under a statistical method and its assumptions. It is not a guarantee that the true effect lies inside that particular interval, and it does not express the probability that the treatment effect equals any particular value. A narrower interval indicates greater precision on the scale of the estimate; a wider interval indicates more uncertainty.

For the primary comparison, the reported interval ranges from 0.062 to 0.362. Since its bounds are both positive, the interval does not include the zero difference. This aligns with the unadjusted p-value of 0.007. A p-value measures how incompatible the observed data are with a specified null hypothesis under the analysis assumptions; it is not the probability that the null hypothesis is true, nor does it measure clinical importance. The registry does not report whether the interval or p-value was adjusted for the multiple outcomes assessed.

Why distinguish statistical and clinical importance?

General explanation: Statistical evidence addresses compatibility with a null model, while clinical importance depends on whether the size and consequences of an effect matter for the intended use. A confidence interval can help readers consider a range of plausible effect sizes, but judging importance also requires a meaningful threshold and context. No threshold for a clinically important risk difference is reported in the registry record. The primary result should therefore be described with its estimate and interval rather than labeled important or unimportant.

What do the secondary measures add?

The listed secondary outcomes cover response at week 2, categories of improvement, individual signs of psoriasis, treatable body surface area, quality of life, and satisfaction with ease of following the program. The detailed results include a week-2 success count and mean change in PQOL-12. The latter is a continuous score, for which the registry reports group means, standard deviations, a mean difference, and its confidence interval. A mean difference describes the contrast between group averages; it does not show how individual participant scores were distributed.

General explanation: A standard deviation describes the spread of individual observations around a group mean. It is not the same as a confidence interval for the mean. For continuous outcomes, the uncertainty in a group comparison depends on the variability of scores and the amount of information in each group. The posted mean-difference interval for PQOL-12 crosses zero, and its unadjusted p-value is 0.527. The interval is more informative than a binary declaration based on a threshold alone because it conveys the range of mean differences compatible with the analysis.

What does the analysis population and LOCF mean?

The primary endpoint is reported for the intent-to-treat population with LOCF. In general, an intent-to-treat approach analyzes participants according to their assigned group, supporting preservation of the randomized comparison. The registry does not give details about exclusions or how this principle was implemented. LOCF uses the last observed value in place of a later missing value. This is an assumption about the unobserved outcome, not simply a neutral way of filling a blank. If outcomes change over time, carrying an earlier value forward may not represent the missing week-4 value. The record does not report missingness by group or sensitivity analyses using alternative assumptions.

Why does multiplicity matter?

General explanation: When many outcomes or comparisons are tested, the chance of obtaining at least one apparently notable result by chance can increase. Prespecification, a testing hierarchy, or an adjustment procedure can address this issue, but the registry record does not report a multiplicity strategy. The primary endpoint is the main stated outcome and is more central than a secondary measure, while unadjusted secondary p-values should be interpreted cautiously. The record lists no reported analysis entries, so details such as model specification, covariate adjustment, and analysis populations for secondary outcomes are not reported.

The registry comparison is not marked as discrepant, so the posted comparison is the basis for interpretation. General statistical explanations above describe how the methods work; they do not add analyses beyond those reported in the registry record.

11. Confidence Intervals and Precision

The primary risk difference is 0.212, with a confidence interval from 0.062 to 0.362. The interval is entirely above zero, indicating that the range of estimates compatible with the reported analysis is positive. Its width also shows that the exact size of the contrast remains uncertain: the registry results support a range of possible magnitudes rather than a single definitive value. The unadjusted p-value is 0.007, but the p-value does not convey the size or precision of the effect by itself.

The posted group counts are 14 of 70 and 28 of 68. Those counts make the direction of the observed comparison easy to understand, but they do not eliminate sampling uncertainty. In general, confidence intervals become narrower when estimates are more precise and wider when the data leave more uncertainty. The record does not report an interval adjusted for multiple outcomes, or a separate analysis accounting for missing data under assumptions other than LOCF.

Precision should not be confused with clinical relevance. The lower confidence bound is above zero, yet the registry record does not specify what risk difference would be large enough to matter clinically. The interval therefore supports interpretation of the statistical contrast, but does not supply a decision threshold. The reported estimate also pertains to the week-4 success definition and does not describe the range of possible effects on later outcomes or on other measures.

The secondary continuous outcome has a mean difference of -2.7 with a confidence interval from -11.07 to 5.669. That interval includes zero, so the posted data leave room for differences in either direction under the analysis. Its breadth is a reminder that a non-significant result is not proof of equality. The registry does not report a prespecified equivalence margin or noninferiority margin for interpreting that comparison.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning illustrations express the required number of participants per arm, not a total across arms and not a total number of events. They use a two-sided significance level of 0.05, equal allocation, and a normal approximation. The effect to detect is set as a stated fraction of the observed effect. These are planning assumptions for an illustration based on the observed result; the trial’s original sample-size justification and design assumptions are not reported in the registry record.

For the primary outcome, planning for 100% of the observed effect gives 74 participants per arm for 80% power and 98 participants per arm for 90% power. Planning for 75% of the observed effect gives 125 participants per arm for 80% power and 166 participants per arm for 90% power. Planning for 50% of the observed effect gives 264 participants per arm for 80% power and 353 participants per arm for 90% power.

In plain terms, the 80% power column describes the planned group size that would give an 80% chance of detecting the specified effect under the stated assumptions if that effect were present. The 90% power column uses a higher probability of detecting it, which requires more participants under the same assumptions. The curve should be read as illustrating the same relationship between the effect size used for planning and participants per arm. Smaller effects need more participants to distinguish them from random variation with the same target power.

These figures are not observed power. They are prospective planning illustrations calculated from the observed effect and do not establish what the original trial was designed to detect.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.200; treatment proportion p₁ = 0.412; average p̄ = 0.306.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6516 = 1.2772.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6342 = 0.5338.
4. n = (1.2772 + 0.5338)² / (0.2118)² = 73.1, rounded up to 74 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.2                          # control proportion
p1 <- 0.411764705882353                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(988637)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 74 (80% power), 98 (90% power)
 75% of observed effect: n per arm = 125 (80% power), 166 (90% power)
 50% of observed effect: n per arm = 264 (80% power), 353 (90% power)
power.prop.test: 73.1 
Simulated power at n = 74 per arm: 0.807 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists 13 outcome measures, spanning the primary endpoint and secondary assessments. Testing many outcomes can increase the chance that at least one comparison appears statistically notable even when no underlying difference exists. This is a general statistical concern known as multiplicity. A prespecified hierarchy, adjustment procedure, or clearly defined distinction between confirmatory and exploratory outcomes can help readers assess the risk, but a multiplicity plan is not reported in the registry record.

The primary outcome is identifiable from the record, but the original analysis plan, its timing relative to enrollment and outcome review, and any planned handling of multiple comparisons are not reported. The registry reports no analysis entries. That absence does not show that investigators conducted no analyses; it means that analysis details are not reported in the registry record. Model choices, covariate adjustments, and the precise methods for the reported intervals and tests are also not described.

The primary analysis population is intent to treat with LOCF. LOCF carries the last observed value forward when a later value is missing. This approach can be simple to apply, but it embeds an assumption that the earlier observation is an adequate substitute for the missing assessment. The number of missing observations, reasons for missingness, and missingness by treatment group are not reported. Sensitivity analyses using alternative missing-data approaches are not reported in the registry record.

Details of secondary-outcome populations and missing-data procedures are likewise not reported. The record does not state whether all outcomes used the same analysis population or whether any outcomes were omitted from analysis. It also does not report an interim-analysis plan, stopping rules, or the original sample-size justification. These omissions limit the ability to determine how much of the analysis strategy was prespecified and how robust the results are to alternative analytical choices. They are limits on interpretation, not evidence that a particular procedure was or was not used.

15. 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 5% reporting threshold.

Most frequent non-serious adverse event terms

For serious adverse events, the registry reports zero affected participants in the weekday/weekend regimen group, with 70 at risk, and zero affected participants in the morning/evening regimen group, with 68 at risk. These are counts over the safety reporting period captured in the registry; the detailed definition and collection procedures for serious events are not reported in the registry record.

The record separately reports other adverse events in the two groups: 4 affected participants among 70 at risk in the weekday/weekend group and 0 among 68 at risk in the morning/evening group. These are descriptive counts and should not be treated as a direct test of a treatment difference. The registry does not provide a statistical comparison for these safety counts or details about event type and severity in the posted adverse-event summary.

Deaths are not reported in the registry record. A zero count of serious events in the posted results does not establish that a regimen is free of risk, particularly when the trial’s treatment period was four weeks and the record does not give further follow-up detail. These figures describe the adverse-event entries recorded for this trial, not a complete assessment of safety in other settings or over longer use.

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

The central result is a higher observed week-4 clear/almost-clear count in the regimen using Clobex® in the morning and Vectical® in the evening than in the regimen using Vectical® on weekdays and Clobex® on weekends. The estimated risk difference is positive, and its reported confidence interval is above zero. This is evidence of a between-group difference in the posted primary outcome under the analysis used, while the interval indicates uncertainty about the difference’s precise size.

The result does not show that every participant in one group had a better outcome, nor does it describe how each participant’s ODS score changed. It summarizes the number meeting a selected success category. It also does not establish a clinically important difference, because a threshold for clinical importance is not reported in the registry record. Nor does the result establish that the schedules differ on every secondary endpoint.

The trial compares two schedules involving the same two treatments. It does not directly compare either schedule with placebo, no treatment, or a regimen containing only one of the treatments. The finding therefore pertains to the relative comparison of these schedules in the studied trial population and over the reported treatment period. The record does not establish persistence beyond week 4, effects in other populations, or outcomes beyond those assessed.

Randomization is a strength for estimating a comparative effect, and evaluator blinding may help limit bias in outcome assessment. However, the registry does not describe random-sequence generation, allocation concealment, adherence, or the practical maintenance of evaluator blinding. The primary population used LOCF, and the extent of missing data and sensitivity to other missing-data assumptions are not reported. These aspects constrain how confidently the estimate can be generalized or interpreted as a complete account of treatment effects.

The posted result is best understood as a statistical comparison of observed week-4 success classifications, accompanied by a confidence interval and an unadjusted p-value. It is not a guarantee of an individual outcome, a measure of long-term benefit, or a stand-alone basis for a treatment decision.

17. Why This Trial Matters Statistically

This trial illustrates why the estimand and outcome definition matter. The primary result is not a mean change in the full ODS scale; it is a count of participants reaching the clear/almost-clear category at week 4. The same scale can support different summaries, and each answers a different question. A dichotomized success count is easy to interpret, but it does not retain all the information in the ordered severity categories.

The comparison also demonstrates the value of reporting an absolute effect with uncertainty. The risk difference gives a direct contrast in success proportions, while the confidence interval shows that the estimated magnitude is not known exactly. A p-value alone would not communicate that range or indicate whether the effect is large enough to matter clinically. No clinical-importance threshold is reported in the registry record, so the estimate and interval should remain the focus rather than a simple significant-or-not label.

The study design gives useful context: random assignment, parallel groups, open-label treatment, and evaluator blinding have different implications for bias. The reported LOCF approach also highlights that the treatment-effect estimate depends on how missing observations are handled. These design and analysis details are not secondary bookkeeping; they affect the interpretation of the observed comparison.

Finally, the many secondary outcomes illustrate the need to distinguish a prespecified primary question from a broader set of exploratory measures. Without a reported multiplicity strategy or analysis plan, secondary results should be weighed cautiously. The trial is therefore a useful example of reading a registry result through the combined lenses of endpoint definition, effect size, precision, missing data, and reporting completeness.

18. 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 are specific to this trial’s registry record. The treatment regimens are described, but detailed information about actual adherence, treatment exposure, protocol deviations, and use of additional therapies is not reported. Those details would help clarify how closely the assigned schedules were followed during the four-week period.

The study was open-label, with evaluator blinding reported but not described in detail. The registry does not explain how assessors remained unaware of treatment assignment or whether blinding was assessed. Because the primary endpoint relies on a severity rating, incomplete information about masking is relevant to interpretation. The methods used to generate the random sequence and conceal allocation are also not reported.

The primary result uses intent to treat with LOCF, but the amount and pattern of missing data are not available in the registry record. There is no reported sensitivity analysis to show whether the result changes under alternative missing-data assumptions. The original sample-size justification, prespecified statistical plan, multiplicity handling, and interim-analysis information are also not reported.

The registry outcome list is broader than the detailed results available. Consequently, the posted record does not permit a complete review of every listed secondary outcome or assessment of consistency across all measures. The safety summary gives serious-event counts and other adverse-event counts, but the record does not provide detailed event descriptions or a statistical safety comparison. The results should therefore be interpreted within the limits of the posted duration, outcomes, and reporting detail, rather than generalized to longer-term use or other populations.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Evaluate Safety/Efficacy of Two Treatment Regimens for Vectical™ Ointment & Clobex® Spray for Moderate Plaque Psoriasis — NCT00988637.
• Registry record last updated 2022-08-01; status last verified 2012-09.
• Results first posted 2011-06-03.
• 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.

22. Record Summary

The registry describes a completed, randomized, parallel-group, open-label, evaluator-blinded phase 4 trial of two Vectical® ointment and Clobex® spray schedules for moderate plaque psoriasis. Enrollment is reported as 138, and the treatment period was 28 days. The primary outcome was the number of participants classified as clear or almost clear at week 4 on the ODS assessment.

The posted primary result was 14 of 70 in the weekday/weekend regimen and 28 of 68 in the morning/evening regimen. The risk difference for the latter relative to the former was 0.212, with a confidence interval from 0.062 to 0.362 and an unadjusted p-value of 0.007. The primary population was intent to treat with LOCF. The original sample-size justification, multiplicity approach, and details of missingness are not reported in the registry record.