Effect of Intravenous (IV) Vedolizumab on Mucosal Healing in Crohn's Disease: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effect of Intravenous (IV) Vedolizumab on Mucosal Healing in Crohn's Disease (NCT02425111), a na phase 3 study. The primary outcome is Part A: Percentage of Participants Achieving Endoscopic Remission at Week 26.

2. Clinical Question

The study asked whether participants with moderately to severely active Crohn’s disease treated with intravenous vedolizumab achieved endoscopic remission at Week 26. Remission was defined using the simple endoscopic score for Crohn’s Disease (SES-CD), with a threshold of ≤4.

This is a descriptive question about the outcome observed in a treated group, not a randomized comparison of vedolizumab with another treatment or with no treatment. The study also listed outcomes for complete mucosal healing, endoscopic remission and response at other time points, and clinical response. Those additional measures broaden the clinical description, but they do not create a concurrent comparison group or establish what would have happened to the same participants under another treatment.

3. Trial Design

The study is titled as an open-label Phase 3b investigation of mucosal healing in moderately to severely active Crohn’s disease. It is recorded as Phase 3, completed, and single-group. The registry lists 101 participants enrolled. Allocation is NA, and masking is none; therefore, the design is not a masked, randomized comparison between treatment arms.

All participants were assigned to a vedolizumab 300 mg treatment schedule. Part A included intravenous doses on Day 1 and Weeks 2, 6, 14, and 22. The listed Part B schedule continued intravenous dosing at Weeks 30, 38, and 46. The record also reports a Part B adverse-event risk group of 56 participants, but the information available does not explain participant flow into that group or provide a detailed account of discontinuations.

The study began on 2015-03-30, reached primary completion on 2017-06-02, and is marked completed. Its stated purpose was to evaluate endoscopic remission at Week 26 using ileocolonoscopy. The primary outcome is a percentage of participants, with a 95% confidence interval specified as the dispersion measure. However, the registry record does not report the primary percentage, its confidence limits, or the number of participants contributing to that specific endpoint result.

Without a concurrent control group, the study can describe outcomes among participants receiving the scheduled treatment, but it cannot isolate a treatment effect from other explanations for those outcomes. Changes over time, participant characteristics, disease course, assessment procedures, and other influences cannot be separated through a randomized between-group contrast in this design. The registry record does not report a protocol-level sample-size justification, a detailed statistical analysis plan, or interim analyses.

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: Participants with a diagnosis of Crohn's Disease were enrolled and received vedolizumab.

Part A: Treatment Period

Reasons for not completing this period:

Part B: Treatment Extension Period

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: FAS included all enrolled participants who received at least 1 dose of study drug.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Full Analysis Set (FAS) included all enrolled participants who received at least 1 dose of study drug.

6. Primary Endpoint

The registry lists the primary outcome as Part A: Percentage of Participants Achieving Endoscopic Remission at Week 26, measured over Week 26.

The primary endpoint is the percentage of participants achieving endoscopic remission at Week 26. The registry defines remission as an SES-CD score of ≤4. Ileocolonoscopy evaluates four endoscopic variables: ulcer size, the proportion of the surface area that is ulcerated, the proportion of the surface area affected, and stenosis. These are assessed in five segments: ileum, right colon, transverse colon, left colon, and rectum. Scores for each variable are summed across segments, and the total SES-CD score ranges from 0 to 56, with higher scores indicating more severe disease.

As a binary endpoint, each participant is classified as meeting or not meeting the remission threshold for the endpoint assessment. The percentage expresses how frequently the endpoint was achieved in the defined analysis population. A confidence interval is used to describe uncertainty around that estimated percentage. The registry specifies a 95% confidence interval, but does not report its limits or the endpoint percentage itself.

Endoscopic measures are used to describe disease findings observed during examination, rather than relying only on participants’ reported symptoms. This endpoint therefore addresses a specific objective of the study: endoscopic remission at the stated time point. It is distinct from the separately listed outcomes of complete mucosal healing, endoscopic response, and clinical response; their definitions and results are not reported in the available registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary endpoint as a percentage with a 95% confidence interval. It does not report the numerical endpoint estimate, the interval limits, or a detailed account of the method used to calculate the interval. The distinctions below are general statistical explanations; they should not be taken as claims about unreported analyses in this study.

What does a percentage estimate?

For a binary outcome, each participant is classified according to whether the endpoint criterion was met. The percentage is the share of the analysis population meeting that criterion. Here, the criterion is an SES-CD score of ≤4 at Week 26. Interpreting a percentage requires knowing both the number meeting the endpoint and the number included in its denominator. The registry defines the primary analysis population as enrolled participants who received at least 1 dose, but does not report the number assessed at Week 26, the number meeting remission, or the endpoint denominator.

What does a confidence interval describe?

General explanation: a confidence interval expresses uncertainty around an estimate. For a percentage, its width depends in part on how much information is available and on the calculation method. A confidence interval is not a guarantee that the true value lies within the displayed range, nor does it account automatically for systematic problems such as missing assessments or biased selection. The record specifies a 95% confidence interval but does not give its bounds or name the calculation method.

A confidence interval around a single-group percentage addresses uncertainty in that group’s estimated outcome. It is not an interval for a treatment-versus-control difference when no comparison group is present. Even a precise estimate of the proportion achieving remission would not, by itself, show what proportion would have achieved remission under a different treatment or without the study treatment.

Why does the study design shape the analysis?

The trial is recorded as single-group, open-label, with no masking and allocation listed as NA. Thus, the primary endpoint is naturally read as a description of outcomes in the treated study population, rather than as a contrast between randomized groups. Open-label status means masking was not used; the registry does not report who performed endoscopy assessments or whether any independent review procedures were used. The record also does not report a comparator, a baseline-adjusted endpoint analysis, or other modeling details.

General explanation: an unadjusted proportion is often straightforward to interpret, while adjusted analyses can account for prespecified factors when their rationale and methods are documented. The registry does not report whether an adjusted analysis was planned or performed. No additional statistical model should be assumed.

How should planning calculations be understood?

General explanation: a sample-size calculation describes how many observations a hypothetical study might need under stated assumptions. It is not a measure of how likely a completed study was to achieve a statistically significant result. The planning illustrations associated with the record are described as calculations from an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. Such illustrations are not the trial’s own design rationale and are not observed power. The registry record does not report the trial’s own sample-size justification. Because this trial is single-group, assumptions involving equal allocation between two arms do not describe its observed study design.

General explanation: over-dispersion is relevant when a model assumes less variability than the data contain; if unaccounted for, uncertainty can be understated. The registry does not report a model for over-dispersion or any evidence that such a model was used. It would not be appropriate to infer one from the endpoint’s percentage format.

What can be concluded from the reported methods?

The record identifies the endpoint definition, its time point, the broad analysis-population definition, and the intended confidence-interval level. Those details support understanding what the study aimed to measure. They do not establish the actual Week 26 result, the precision of that result, the handling of missing outcome measurements, or the statistical procedure used to produce an estimate. Those details are not reported in the registry record.

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("Vedolizumab 300 mg")
n      <- c(101)
events <- c(12)
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  Vedolizumab 300 mg  101  12  11.9  6.3  19.8  6.9  19.6  7.0  19.6

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 15 outcome measures, including the primary Week 26 endoscopic remission outcome and secondary measures of complete mucosal healing, endoscopic remission, endoscopic response, and clinical response at different time points. It records 0 analyses. The presence of several outcomes and assessment times raises a general multiplicity issue: when many statistical questions are tested, the chance of at least one apparently notable result can increase. That general concern does not establish that the study conducted multiple hypothesis tests.

The registry record does not report whether any multiplicity adjustment was planned or used, which outcomes were treated as confirmatory, or whether a hierarchy of tests was prespecified. It also does not report p-values for the primary or secondary outcomes. Therefore, statistical significance and any correction for multiple testing cannot be evaluated from this record.

The primary analysis population is defined as all enrolled participants who received at least 1 dose of study drug. The registry does not report the number included in the Week 26 endpoint analysis, the amount or pattern of missing endoscopy data, reasons for missing assessments, or the method used to handle missing outcomes. It is also not reported in the registry record whether the analysis used an intention-to-treat approach, a complete-case approach, imputation, or another strategy. These distinctions matter because the percentage can depend on which participants are included and how unavailable outcomes are treated.

The registry’s population definition should therefore be read as a stated analysis-population description, not as evidence that every enrolled participant contributed an evaluable Week 26 result. Neither missing-data handling nor sensitivity analyses are reported in the registry 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: crohn's disease (5.9%), coronary artery disease (1.8%), subileus (1.8%), infected bite (1.8%), urinary tract infection (1.8%).

The registry reports adverse-event counts for two vedolizumab risk groups. In Part A, 12 of 101 participants are listed in the serious adverse-event category, and 26 of 101 in the other adverse-event category. In Part B, the corresponding counts are 6 of 56 and 9 of 56. The record reports 0 deaths in each group. These are descriptive counts; no control group is available for comparison.

The serious-event terms with the largest listed percentages include Crohn’s disease at 5.9%, and coronary artery disease, subileus, infected bite, urinary tract infection, and postoperative ileus, each at 1.8%. The registry does not state in these figures whether events were considered related to treatment, how terms were selected for listing, or whether an individual could contribute to more than one term. Those percentages should therefore be read as reported event-term summaries, not as evidence of causation.

The Part A and Part B risk groups have different participant counts. The record does not explain participant flow into Part B or establish that these groups are independent. Their counts should not be treated as a randomized comparison or combined into a new total. General statistical interpretation: event counts describe what was recorded in the stated risk group, while comparison of risks requires clear denominators, follow-up definitions, and a suitable comparator. These figures alone do not establish whether treatment caused an event.

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

The study was designed to describe endoscopic remission at Week 26 among participants treated with intravenous vedolizumab. The registry provides the remission threshold, the SES-CD components, the broad analysis-population definition, and the intended use of a 95% confidence interval. It does not report the Week 26 percentage, the interval limits, or the endpoint-specific denominator. As a result, the registry record does not establish how often remission was observed or how precisely that proportion was estimated.

Even if a single-group proportion is reported elsewhere, the design determines what it can mean. This trial had no control group and was open-label. A percentage in the treated group can describe observed outcomes in that group, but it cannot on its own estimate a comparative treatment effect. Differences between an observed outcome and an imagined alternative outcome cannot be measured from this design alone.

The endpoint is specifically endoscopic remission under the SES-CD definition. It is not interchangeable with the separately listed measures of complete mucosal healing, endoscopic response, or clinical response. The registry lists those outcomes at some of the same or different time points, but their result values and any relationships among them are not reported in the registry record.

The safety counts provide another kind of description: numbers recorded in the Part A and Part B risk groups. They do not supply a control-based estimate of excess risk, and the registry information does not establish whether events were caused by vedolizumab. The reported zero deaths applies to the listed groups as recorded; it does not answer questions outside those groups or the record’s reporting scope.

General explanation: statistical uncertainty and study-design limitations are different. A narrow confidence interval, if one were available, could indicate precision for a proportion while leaving the lack of a control group unchanged. Conversely, a broad interval would indicate imprecision but would not explain its cause. Here, the confidence interval is specified but its values are not reported, so neither precision nor comparative effect can be assessed from the registry record.

14. Why This Trial Matters Statistically

This study illustrates why an endpoint definition and a study design must be read together. The primary measure is a binary classification at a specific time point: endoscopic remission at Week 26, defined as SES-CD ≤4. The score itself combines four endoscopic variables across five bowel segments. This makes the outcome clinically specific, while also making clear that the reported percentage depends on who had an evaluable assessment and how the endpoint was summarized.

The study is single-group and open-label. Those features do not prevent the study from describing outcomes among participants, but they limit what can be learned about comparative effects. Without a concurrent control group, outcome percentages cannot separate treatment-associated change from other influences. Statistical precision for a single proportion, even when reported, would not resolve that design limitation.

The record also shows why completeness of reporting matters. It specifies a 95% confidence interval and defines the analysis population broadly, but does not report the estimate, interval limits, endpoint denominator, or missing-data handling. Those omissions prevent assessment of both the observed endpoint level and its uncertainty. Listing multiple secondary outcomes and time points also makes the absence of reported multiplicity methods relevant to interpretation, without implying that any particular adjustment was required or performed.

Finally, separate adverse-event counts for Part A and Part B are not a substitute for a comparative safety analysis. Their denominators differ, and the registry does not provide a control group or enough detail to infer event causation. The statistical lesson is not that the study lacks descriptive value, but that the conclusions available from it depend on its single-group structure and the completeness of reported outcome and analysis information.

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 trial-specific limitation is the absence of a comparator. The record describes a single-group, open-label study, so observed outcomes cannot be interpreted as a randomized treatment contrast. It is not possible to separate treatment effects from natural changes over time, other influences, or differences in who completed endoscopic assessment using the design information reported.

The primary endpoint result is not reported in the registry record. The percentage achieving remission, its 95% confidence interval, and the number assessed at Week 26 are unavailable. Although enrollment was 101 and the primary analysis population is defined by receipt of at least 1 dose, the endpoint denominator cannot be inferred from those details. The registry also does not report how missing Week 26 assessments were handled.

The record lists multiple secondary outcomes and time points but does not report the analysis methods, multiplicity strategy, p-values, or outcome estimates. It does not report whether endoscopy assessment was masked, independently reviewed, or subject to another quality-control process. No protocol-level sample-size justification, interim analysis plan, or detailed statistical analysis plan is reported in the registry record.

For safety interpretation, Part A and Part B have different reported risk-group sizes. Participant flow between the treatment parts, exposure duration for each individual, and event relatedness are not established by the information presented. The adverse-event counts therefore remain descriptive and should not be treated as comparative risks.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Effect of Intravenous (IV) Vedolizumab on Mucosal Healing in Crohn's Disease — NCT02425111.
• Registry record last updated 2018-09-14; status last verified 2018-08.
• Results first posted 2018-09-14.
• 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

NCT02425111 is a completed, open-label, single-group Phase 3b study of intravenous vedolizumab in moderately to severely active Crohn’s disease. The registry lists 101 participants enrolled and identifies endoscopic remission at Week 26 as the primary outcome. Remission is defined as an SES-CD score of ≤4, and the intended summary measure is a percentage with a 95% confidence interval.

Part A dosing was vedolizumab 300 mg intravenously on Day 1 and Weeks 2, 6, 14, and 22. The listed Part B schedule continued dosing at Weeks 30, 38, and 46. The primary percentage, confidence interval limits, endpoint denominator, missing-data methods, and detailed analysis plan are not reported in the registry record. Safety counts are reported for Part A and Part B risk groups, with 0 deaths listed in each.