A Study to Evaluate Remicade (Infliximab) in Moderate-to-Severe Chronic Plaque Psoriasis in the Middle Eastern Population (Study P04528): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study to Evaluate Remicade (Infliximab) in Moderate-to-Severe Chronic Plaque Psoriasis in the Middle Eastern Population (Study P04528) (NCT00687362), a na phase 2 study. The primary outcome is Psoriasis Area and Severity Index 75 (PASI75) Response at Week 10.

2. Clinical Question

This is a descriptive question about the response observed in the enrolled group, not a randomized comparison of infliximab with another treatment or with no treatment. Without a comparator, the study cannot separate changes associated with treatment from changes that might occur for other reasons. Open-label conduct also means participants and study personnel were not masked to treatment assignment; the record does not describe further safeguards or assessment procedures.

The registry record states that both safety and efficacy were to be evaluated. However, it reports no primary outcome analysis and gives no PASI75 responder count. As a result, the central response question cannot be answered from the posted results. The record’s safety counts are a separate type of evidence and should not be taken as a substitute for the missing response result.

3. Trial Design

This was a completed Phase 2, multicenter, multinational, open-label, single-group study of infliximab monotherapy for moderate-to-severe chronic plaque psoriasis in a Middle Eastern population. The registry lists 22 participants as enrolled and identifies infliximab as the intervention. The study is not described as a randomized comparison: allocation is listed as not applicable, masking as none, and the design model as single group.

The regimen was infliximab 5 mg/kg of body weight by infusion at Weeks 0, 2, 6, 14, and 22. The primary outcome was PASI75 response at Week 10. This outcome is defined as achieving at least a 75% improvement in PASI score from baseline to Week 10. The study description says safety and efficacy would be evaluated.

The registry lists the study as completed, with a start date of 2006-05-30 and a primary completion date of 2008-11-11. Those dates describe the registered study timeline; they do not supply details about recruitment, follow-up completion for individual participants, or the timing of analysis.

A single-group design can describe what occurred among participants receiving the intervention, but it does not provide a concurrent control for comparison. Open-label conduct indicates that masking was absent. The registry record does not report a protocol-level explanation for choosing this design, a sample-size justification, details of site conduct, or a statistical analysis plan. It lists one outcome measure and no analyses, so the design description should not be mistaken for evidence that the primary endpoint was successfully analyzed or reported.

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

Reasons for not completing this period:

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 Psoriasis Area and Severity Index 75 (PASI75) Response at Week 10, measured over 10 weeks.

The primary endpoint is the number of participants with a PASI75 response at Week 10. A response is defined as at least a 75% improvement in PASI score between baseline and Week 10. PASI is a system for assessing and grading the severity of psoriatic lesions and their response to therapy; its score can range from 0 to 72, with higher scores indicating worse disease.

Expressing the outcome as a response threshold makes the endpoint a binary measure: each participant either meets the stated improvement criterion or does not. The count of responders can communicate how many participants crossed that threshold in the study group. It does not show the size of each participant’s improvement beyond the threshold, nor does it describe the full distribution of PASI changes. Those would require different summaries.

A threshold outcome is useful for describing whether a prespecified degree of improvement was reached by the assessment time. Its interpretation depends on a clear baseline and Week 10 assessment and on how participants without an observed assessment are handled. The registry record does not report the responder count, the denominator used for the endpoint analysis, missing-data handling, or the analysis population. Consequently, the endpoint is defined, but its observed result and precision cannot be assessed from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a binary primary outcome: whether a participant met the PASI75 response definition at Week 10. Binary outcomes classify each participant according to whether a specified condition was met. A count of participants meeting the definition can be straightforward to understand, but interpreting it requires knowing the number assessed and the rules used for participants whose endpoint status is unknown. The record does not report the primary responder count, analysis denominator, or missing-data rules.

What does the endpoint count represent?

PASI75 is based on change from baseline in PASI score. The registry defines response as at least a 75% improvement by Week 10. The PASI grades severity of psoriatic lesions, with higher scores representing worse disease and a stated range from 0 to 72. A threshold response compresses a continuous score change into a yes-or-no outcome. This can make the endpoint easier to interpret as attainment of a stated level of improvement, but it does not preserve all information about the amount of change. Two participants on opposite sides of a threshold may have similar score changes, while participants who both meet it may differ in the extent of their improvement.

Why does the study design matter?

This study is listed as single group, open label, with no masking and no applicable allocation. The intervention was infliximab 5 mg/kg at the specified infusion visits. With no separate control group, the study can describe outcomes in the treated group but cannot make a randomized, like-for-like comparison. In general, random allocation helps create groups that are comparable on average, while a concurrent comparator can provide context for changes over time. These are general statistical principles; the registry does not report such a comparison for this study.

Open-label design means treatment knowledge was not masked. In general, awareness of treatment can influence reporting, participant behavior, or outcome assessment, depending on how outcomes are collected. The registry record does not describe the assessment procedures or any measures used to limit such influences. The endpoint uses a score-based response definition, but that fact alone does not establish how assessments were conducted.

What can confidence intervals and significance tests tell readers?

A confidence interval expresses uncertainty around an estimate under a specified statistical model and analysis procedure. For a binary response, an interval around a response estimate would help show the range of values compatible with the observed data under those assumptions. A significance test addresses a different question, assessing how compatible the data are with a stated null hypothesis under its assumptions. Neither a confidence interval nor a test can be interpreted without the underlying estimate, analysis population, and method. The registry record reports no primary analysis, estimate, interval, or test result.

The record includes planning assumptions for illustrative sample-size calculations: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects expressed as a stated fraction of the observed effect. These assumptions are described as planning illustrations rather than the trial’s own design. They do not establish that the study planned two arms, since the registered study is single group, nor do they provide evidence of observed power. The record does not report a sample-size justification for the trial. No planning estimate should be interpreted as an observed clinical result.

How should the posted safety counts be read?

The serious-event summary gives a count affected and a count at risk. It reports 0 affected among 22 at risk. The summary for other adverse events reports 11 affected among 22 at risk. These are counts, not comparative effect estimates. A rate or risk comparison would require a clearly defined denominator and appropriate comparison data; no control arm is reported. The record does not provide event-level details for the serious-event summary, and deaths are not reported. General statistical interpretation also depends on consistent event definitions, observation periods, and completeness of capture, details not established by these counts.

There is no reported over-dispersion analysis or model-based outcome analysis to interpret. Over-dispersion is a general concern when variability in count data exceeds what a statistical model assumes; it can make model-based uncertainty estimates too narrow if ignored. It is not possible to determine whether that issue applies to this study’s primary outcome, which is binary and has no reported analysis. The registry record also does not report interim analyses, a multiplicity procedure, or an analysis plan.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Infliximab 5 mg/kg")
n      <- c(22)
events <- c(16)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Infliximab 5 mg/kg  22  16  72.7  49.8  89.3  51.8  86.8  51.6  86.8

11. Multiplicity, Missing Data and Analysis Populations

Multiplicity concerns arise when several outcomes, time points, subgroups, or statistical tests are examined. In general, testing many questions can increase the chance that at least one result appears unusual by chance, so interpretation may depend on whether the analysis plan prespecified a primary outcome and how additional tests were handled. The registry identifies PASI75 response at Week 10 as the primary outcome and lists one outcome measure, but the analysis plan and any multiplicity strategy are not reported in the registry record. The record does not report interim analyses.

Missing-data handling is also important for a binary response endpoint. Participants without an observed Week 10 status may be treated in different ways, and those choices can affect the estimate. The registry record does not report how missing baseline or follow-up assessments were handled, whether all enrolled participants were included in the primary analysis, or the primary analysis denominator. It therefore does not support assumptions about imputation, exclusion, or nonresponse rules.

The analysis population is not reported in the registry record. The enrollment count is listed as 22, but this alone does not establish which participants contributed to the primary endpoint analysis or to each safety summary. The record lists no analyses, and does not provide a statistical analysis plan, subgroup results, or adjustment methods. These absences limit assessment of bias and analytical robustness; they do not indicate which methods were used outside the posted record.

12. 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

The safety summary reports 0 participants affected by serious adverse events among 22 participants at risk. It separately reports 11 participants affected by other adverse events among 22 at risk. These counts describe participants recorded as affected in the registry summary; they are not measures of comparative risk because the study has no separate control group.

The serious adverse event terms are not listed in the record’s top serious terms, and the death count is not reported in the registry record. The other adverse event count does not identify the event types, severity, timing, duration, or whether participants experienced more than one event. It should not be interpreted as a count of all individual event occurrences. The record also does not provide information about event-related treatment discontinuations or follow-up completeness.

In general, safety counts depend on how adverse events are defined, collected, and summarized, as well as the period during which participants are observed. Those details are not reported in the registry record. A zero count in a posted summary means no affected participants were recorded in that summary; it is not proof that an event is impossible or that safety has been established. The counts provide descriptive information only and do not answer the missing PASI75 efficacy question.

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

The record establishes that a Phase 2, open-label, single-group study evaluated infliximab monotherapy in Middle Eastern participants with moderate-to-severe chronic plaque psoriasis. It describes the infusion schedule and defines the primary endpoint as PASI75 response at Week 10. It also reports selected safety counts. These details allow readers to understand the study question and the nature of the posted safety information.

The record does not report the number of participants who achieved PASI75, an estimate of the response, or an interval describing its precision. It lists no analyses. Accordingly, it does not provide a quantitative primary result that can be interpreted as showing the extent of response in the study group. This absence is not evidence that no participants responded, nor is it evidence that all participants responded.

Even if a response count were available, the single-group design would not establish how outcomes compare with another treatment or with no treatment. In general, changes observed during a study can reflect multiple influences, and a concurrent randomized comparator helps support causal comparisons. The open-label design and unreported assessment details also leave unanswered questions about how outcomes were collected and analyzed.

The safety counts indicate that the registry summary recorded 0 participants affected by serious adverse events and 11 affected by other adverse events, each among 22 at risk. They do not establish comparative safety, describe individual events, or substitute for a complete safety analysis. The death entry is not reported. These constraints matter when interpreting what the record can support.

The appropriate reading is therefore limited: the registry describes the study and some safety counts, but it does not publish the primary response analysis. Conclusions about the size, precision, or comparative meaning of PASI75 response cannot be drawn from the posted results.

14. Why This Trial Matters Statistically

This study illustrates the distinction between a clearly defined outcome and a reported outcome result. PASI75 response at Week 10 is specified in terms of a baseline-to-follow-up improvement threshold, and the registry explains the PASI score’s role in grading disease severity. Yet an endpoint definition alone is not an estimate. Without the responder count, denominator, and analysis, readers cannot quantify the result or its uncertainty.

The single-group, open-label design is also important to statistical interpretation. It can document what was observed among participants receiving infliximab, but it does not supply a randomized control comparison. That limits causal interpretation and makes it impossible to estimate a between-group treatment contrast from the posted record. The design description should therefore guide the scope of any conclusions drawn from the registry.

The safety summary demonstrates another distinction: counts of affected participants can be reported even when the primary endpoint analysis is absent. These safety counts are useful descriptive information, but their meaning is bounded by missing event-level details, no control group, and unreported analysis procedures. They should not be treated as a complete account of safety or as evidence about efficacy.

Finally, the registry record reports no analyses and does not describe missing-data rules, analysis populations, interim analyses, or the trial’s sample-size justification. These omissions prevent assessment of important analytical choices. Statistically, the record matters as an example of why readers need results as well as design and endpoint definitions, and why the amount of information available determines how far interpretation can go.

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.

The principal limitation for interpreting efficacy is that the registry identifies a primary endpoint but does not report its result. There is no PASI75 responder count, analysis denominator, effect estimate, confidence interval, or test result. The record lists no analyses, so the primary outcome’s magnitude and precision cannot be evaluated.

The design is single group and open label, with no separate comparator. Any reported outcome would therefore be descriptive of the study group rather than a randomized treatment contrast. Masking is listed as none. The registry record does not describe outcome-assessment procedures or safeguards against possible influences of treatment knowledge.

The record lists 22 enrolled participants, but does not report the primary analysis population or how participants with missing assessments were handled. It also does not report participant characteristics beyond the broad population description, protocol details for eligibility, or a sample-size justification. The planning assumptions for illustrative sample-size calculations are not the trial’s own design and do not resolve these gaps.

Safety interpretation is limited by the absence of serious-event terms, detailed other-event information, and a reported death count. The record does not provide event timing, duration, severity, or treatment-relatedness. It also does not report follow-up completeness or the statistical plan, multiplicity handling, or interim analyses. These limitations describe what cannot be assessed from the registry record; they do not establish that the unreported methods or information were absent from the conduct of the study.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study to Evaluate Remicade (Infliximab) in Moderate-to-Severe Chronic Plaque Psoriasis in the Middle Eastern Population (Study P04528) — NCT00687362.
• Registry record last updated 2017-05-10; status last verified 2017-04.
• Results first posted 2010-03-09.
• 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

The registry record describes a completed Phase 2, multicenter, multinational, open-label, single-group study of infliximab monotherapy in Middle Eastern participants with moderate-to-severe chronic plaque psoriasis. Enrollment is listed as 22. Infliximab 5 mg/kg was administered by infusion at Weeks 0, 2, 6, 14, and 22.

The primary outcome was PASI75 response at Week 10, defined as at least a 75% improvement in PASI score from baseline. The outcome result is not reported, and the record lists no analyses. Safety summaries report 0 participants affected by serious adverse events among 22 at risk and 11 affected by other adverse events among 22 at risk. The death count is not reported in the registry record.

The single-group design provides no concurrent comparator. The record does not report the primary analysis population, missing-data methods, analysis plan, or sample-size justification. As a result, the posted information describes the study design and selected safety counts but does not allow assessment of the primary endpoint’s observed response or precision.