Open-label Study of Adalimumab in Japanese Subjects With Hidradenitis Suppurativa: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Open-label Study of Adalimumab in Japanese Subjects With Hidradenitis Suppurativa (NCT02904902), a na phase 3 study. The primary outcome is Percentage of Participants Achieving Hidradenitis Suppurativa Clinical Response (HiSCR) at Week 12.

2. Clinical Question

3. Trial Design

This was a Phase 3, multicenter, open-label, single-arm study of adalimumab in Japanese subjects with moderate to severe hidradenitis suppurativa. The record lists an enrollment of 15 and a completed status. The recorded start date is 2016-09-06 and the primary completion date is 2017-09-01. The record does not state the number of participating centers.

All participants were assigned to the adalimumab arm. The listed regimen began with 160 mg by subcutaneous injection at Week 0 (Baseline), followed by 80 mg at Week 2 and 40 mg every week from Week 4. After Week 52, participants who consented to an 80 mg every-other-week dose were to switch from 40 mg every week to that schedule for the remaining study period. The record does not provide further details about treatment duration or the timing described as Week 0x.

Because the study was open-label and had no comparator, it was not designed as a randomized treatment comparison. Its results can describe the observed outcomes in the enrolled group, but by themselves cannot separate treatment-associated changes from other explanations, such as the course of HS over time or changes in assessment. Four outcome measures are listed, including the primary HiSCR outcome and secondary outcomes involving abscess and nodule count, skin-pain response, and Modified Sartorius Scale score. The registry record lists zero analyses, and numerical outcome estimates are 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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Full Analysis Set: all participants from sites that complied with Good Clinical Practice and received at least 1 dose of study drug and had at least 1 post-treatment efficacy assessment. Non responder imputation.

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 Percentage of Participants Achieving Hidradenitis Suppurativa Clinical Response (HiSCR) at Week 12, measured over Week 12.

The primary endpoint was the percentage of participants achieving HiSCR at Week 12. The response definition required at least a 50% reduction from Baseline in the total count of abscesses and inflammatory nodules, alongside no increase in abscess count and no increase in draining fistula count. It therefore combines improvement in inflammatory lesion burden with conditions intended to prevent worsening in the specified lesion categories.

A percentage is suitable for expressing how many participants in a defined analysis population met a binary response criterion. It is more interpretable than a raw lesion-count change when the clinical question is whether a participant crossed a prespecified response threshold. The record specifies a 95% confidence interval for the percentage, which would convey uncertainty around the estimated response in the study population. However, neither the observed percentage nor the confidence interval is reported in the registry record, so the magnitude and precision of the primary result cannot be assessed from this record.

The primary endpoint was assessed at Week 12. The record also specifies non-responder imputation and defines the Full Analysis Set as participants from sites complying with Good Clinical Practice who received at least one dose and had at least one post-treatment efficacy assessment. The precise implementation details beyond the named imputation approach are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods are easiest to interpret by separating the outcome definition, the analysis population, and the uncertainty around an estimate. The registry record supplies some of this information for the primary endpoint, but it does not report the numerical endpoint result or many details of the statistical plan.

What does a percentage endpoint represent?

The primary outcome is binary at the participant level: a participant meets the HiSCR response definition or does not. The percentage is the share of the analysis population classified as responders. The criterion is based on change from Baseline to Week 12: at least a 50% reduction in total abscess and inflammatory nodule count, with no increase in abscess count and no increase in draining fistula count. This is a threshold-based summary, not an estimate of the average change in lesion counts.

As a general statistical concept, a binary percentage is an estimate of a proportion in the population represented by the study participants. Its precision depends on the amount of information in the data and on how many participants meet the response definition. The record specifies a 95% confidence interval. In general, a confidence interval gives a range of values compatible with the observed data under the method used; it is not a guarantee that a particular value is the true population value. The record does not give the interval or identify the specific calculation method, so neither the width nor the method-specific properties can be assessed.

Who was included in the primary analysis?

The Full Analysis Set is described as all participants from sites that complied with Good Clinical Practice who received at least one dose of study drug and had at least one post-treatment efficacy assessment. Thus, the primary analysis population is not defined simply as everyone enrolled: it includes stated treatment and assessment conditions. The record does not report how many participants met this definition or whether any participants were excluded from it.

The primary outcome specifies non-responder imputation. In general, this approach classifies a participant with missing response information as not having achieved the response. This can make the result depend on how missing assessments are handled. The exact missing-data patterns, reasons for missingness, and implementation details are not reported in the registry record. Non-responder imputation should therefore be understood as the stated approach, not as a complete account of missing-data handling.

What does the single-arm design permit?

There is no randomized control group. A response percentage can describe the observed group, but it cannot provide a direct randomized estimate of the difference between adalimumab and a comparator. General statistical interpretation of uncontrolled outcomes must allow for other explanations of change over time, including the natural course of the condition, assessment variation, and other influences. This is a limitation of the design, not a calculation issue that a confidence interval can resolve.

The open-label designation means masking was none. In general, knowledge of treatment assignment can influence participant reports or assessments, although the record does not establish that such influence occurred. The endpoint includes lesion counts and the secondary outcomes include patient-reported skin pain, but the record does not describe assessor masking or other procedures that could clarify this concern.

What is known about other analyses?

Four outcome measures are listed: the primary HiSCR outcome and secondary measures involving abscess and nodule count, skin pain, and Modified Sartorius Scale score. The record lists zero analyses. It does not report numerical results for those outcomes, model specifications, covariate adjustments, or an inferential procedure for secondary outcomes. Details of interim analyses and the statistical plan are not reported in the registry record.

Multiplicity is a general concern when several outcomes or comparisons are examined: the chance of at least one apparently notable result can increase as the number of statistical tests grows. Whether and how that issue was addressed is not reported. No p-value for the primary result is given, so there is no reported significance test to interpret.

How should planning calculations be read?

The record describes planning illustrations using a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect set as a stated fraction of the observed effect. Such calculations are planning illustrations rather than observed trial results, and they are not a justification for the actual enrollment unless the record says so. The record does not report its own sample-size justification. The stated two-arm assumptions also differ from the actual single-arm design, so the illustrations should not be read as the design or analysis of this study. Any sample size derived from those assumptions is not observed power.

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("Adalimumab")
n      <- c(15)
events <- c(13)
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  Adalimumab  15  13  86.7  59.5  98.3  62.1  96.3  61.7  96.0

11. Multiplicity, Missing Data and Analysis Populations

The record lists four outcome measures: the Week 12 HiSCR primary endpoint and secondary outcomes for abscess and nodule count, skin-pain response, and Modified Sartorius Scale score. It does not state whether the secondary outcomes were tested using a prespecified hierarchy, an adjustment for multiple testing, or another multiplicity strategy. The significance threshold for the primary outcome and any testing plan are not reported in the registry record. As a general statistical point, considering several outcomes can raise the chance of a false-positive finding if each is tested without accounting for the set of tests. This concern cannot be evaluated fully without the analysis plan and results.

The primary endpoint names non-responder imputation. In general, this means missing response information is treated as non-response for the endpoint. The Full Analysis Set also requires receipt of at least one dose and at least one post-treatment efficacy assessment at a site complying with Good Clinical Practice. The record does not report how many enrolled participants met that definition, the amount or reasons for missing data, or further details about imputation implementation. It is therefore not possible to assess the impact of missing observations or compare alternative missing-data assumptions.

The registry record lists zero analyses and does not provide numerical results for the primary or secondary outcomes. It also does not report interim analyses, a full statistical analysis plan, or the sample-size justification. These omissions limit the assessment of selective reporting, analysis choices, and the planned treatment of multiple endpoints. Absence of these details in the registry record does not establish what procedures were or were not used outside the record.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cellulitis (13.3%), subcutaneous abscess (6.7%), uterine leiomyoma (6.7%), interstitial lung disease (6.7%), deep vein thrombosis (6.7%).

The safety figures are descriptive counts within the adalimumab group. The record lists 15 participants at risk for serious adverse events and 5 affected. It lists 15 participants at risk for other adverse events and 15 affected. Deaths are listed as 0. These counts should not be read as comparisons with an untreated or alternative-treatment group, because the trial had no comparator.

The listed serious adverse event terms include cellulitis at 13.3%, subcutaneous abscess at 6.7%, uterine leiomyoma at 6.7%, interstitial lung disease at 6.7%, and deep vein thrombosis at 6.7%. These are the percentages reported in the registry record; it does not provide event counts for each listed term in the information. The term-specific percentages should not be added together, since an individual may experience more than one event and the record does not describe overlap.

In general, serious adverse event summaries describe observed events under the study’s reporting definitions; they do not by themselves establish whether an event was caused by the study drug. The record does not provide a causal assessment, event timing, duration, severity details beyond the serious classification, or a comparative safety estimate. The small study cohort also means these figures are descriptive of this group rather than a precise estimate of event rates in a broader population.

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

The record establishes that a Phase 3 study evaluated adalimumab in Japanese subjects with moderate to severe hidradenitis suppurativa using an open-label, single-arm design. It also defines the primary response at Week 12 and identifies the analysis population and non-responder imputation. Those details clarify what the primary outcome was intended to measure.

However, the registry record does not report the observed percentage achieving HiSCR or its 95% confidence interval. Without those values, the magnitude and precision of the primary result are unknown from this record. The numerical results for the listed secondary outcomes are also not reported in the registry record. Thus, the study’s stated question can be described, but its primary efficacy result cannot be summarized quantitatively from the posted data.

Even if a response percentage is available elsewhere, a result from a single-arm, open-label study is descriptive of the participants studied. Without a randomized comparator, it does not estimate a comparative treatment effect. A confidence interval can describe statistical uncertainty in a proportion, but it cannot remove limitations arising from the lack of a control group or open-label conduct.

The safety figures report adverse events observed among study participants, including serious adverse events in 5 of 15 participants and 0 deaths. Those figures do not establish comparative risks or prove that the study drug caused any particular event. The record also does not provide enough detail to assess timing, event-level overlap, or causal attribution.

These findings should therefore be read as a description of a completed study and its registry reporting, not as a stand-alone basis for claims about treatment benefit or harm. The absence of numerical efficacy results in the registry record is a reporting limitation; it is not evidence that no outcome was measured or that no analysis occurred.

14. Why This Trial Matters Statistically

This study is statistically notable for the contrast between a precisely defined response endpoint and the absence of its numerical result in the registry record. HiSCR is specified through a threshold for reduction in abscess and inflammatory nodule counts, together with conditions against increases in abscesses and draining fistulas. That definition makes the intended Week 12 outcome understandable, but a definition alone cannot show how many participants met it or how uncertain the estimate was.

The single-arm structure is also central to interpretation. An observed percentage can characterize participants receiving adalimumab, but there is no randomized comparator for estimating a treatment contrast. This distinction is important because within-group change and comparative effect answer different statistical questions. The open-label design adds another consideration for outcomes based on assessment, while the record does not report enough procedural detail to determine how that concern was managed.

The registry record identifies a Full Analysis Set and non-responder imputation, which are essential elements for interpreting a proportion when some response assessments may be absent. Yet it does not report the number in the analysis set or missing-data details. The listed secondary outcomes introduce further questions about multiplicity, but the record does not state an adjustment or hierarchy.

Finally, the adverse-event summaries illustrate why descriptive safety counts should not be mistaken for comparative estimates. They report events in a cohort of 15, without a control group. Together, these features show that statistical interpretation depends not only on endpoint definitions and calculations, but also on design, analysis population, missingness, and transparent reporting of estimates. The unavailable primary estimate is a key limit on what can be concluded from this registry record.

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 main limitation for interpreting efficacy is that the registry record does not report the numerical primary endpoint result or its 95% confidence interval. Numerical results for the secondary outcomes are also not reported. Although the primary endpoint definition and analysis population are described, readers cannot assess the response percentage, its precision, or the pattern of secondary findings from this record.

The trial enrolled 15 participants and had no comparator. The observed group can be described, but the design cannot isolate a comparative treatment effect. Open-label conduct is another limitation; masking is listed as none. The record does not report whether outcome assessors were masked or describe procedures for limiting possible assessment influences.

Further limitations arise from incomplete analysis detail. The Full Analysis Set criteria and non-responder imputation are stated, but the number analyzed, the missing-data pattern, and the exact imputation implementation are not reported in the registry record. The record lists four outcome measures but does not describe a multiplicity strategy, statistical models, interim analyses, or a full statistical analysis plan. A sample-size justification is not reported in the registry record.

The safety information is limited to group-level at-risk and affected counts, deaths, and a list of serious adverse event terms with percentages. The record does not report event timing, term-specific counts, causal assessment, or comparative safety data. These limitations constrain both the precision and scope of interpretation; they do not establish that unreported procedures or analyses were absent outside the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Open-label Study of Adalimumab in Japanese Subjects With Hidradenitis Suppurativa — NCT02904902.
• Registry record last updated 2020-05-12; status last verified 2020-04.
• Results first posted 2019-02-27.
• 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 3, multicenter, open-label, single-arm study of adalimumab in Japanese subjects with moderate to severe hidradenitis suppurativa. Enrollment was 15. The recorded study start was 2016-09-06, and primary completion was 2017-09-01.

The primary endpoint was the percentage achieving HiSCR at Week 12, using a defined lesion-count response criterion. The Full Analysis Set and non-responder imputation are described. Four outcome measures are listed, but the registry record does not report numerical primary or secondary results, including the primary percentage and its 95% confidence interval.

For safety, the record lists 5 of 15 participants affected by serious adverse events, 15 of 15 affected by other adverse events, and 0 deaths. No randomized comparator is listed. The registry record does not report a sample-size justification or full statistical analysis plan.