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Severe Steroid-Dependent Asthma Phase 3 OCS Reduction NCT02528214

VENTURE: Complete Statistical Analysis of Dupilumab in Severe Steroid-Dependent Asthma

An independent statistical review of the randomized phase 3 VENTURE trial evaluating dupilumab 300 mg every 2 weeks versus placebo in patients with severe steroid-dependent asthma, with particular emphasis on oral corticosteroid reduction while maintaining asthma control.

Trial status: Completed  ·  Enrollment: 210  ·  Primary completion: September 20, 2017
Scope of this record

This page separates reported trial results from statistical interpretation. Numerical results are restricted to the information reported in the ClinicalTrials.gov record. The registry provides the official trial record.

Registry note: This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record.

1. Trial at a Glance

VENTURE was a randomized, parallel-group, triple-masked phase 3 trial evaluating dupilumab in patients with severe steroid-dependent asthma. The principal statistical question was whether dupilumab increased the reduction in oral corticosteroid (OCS) dose that could be achieved at Week 24 while maintaining asthma control.

210
Enrolled
103 dupilumab; 107 placebo
2
Treatment arms
Parallel-group randomized design
28.24
Primary LS mean difference
95% CI 15.81–40.67
< 0.0001
Primary p-value
Two-sided superiority test
FeatureVENTURE
Trial nameVENTURE
ClinicalTrials.gov identifierNCT02528214
Brief titleEvaluation of Dupilumab in Patients With Severe Steroid Dependent Asthma
Therapeutic areaPulmonology
ConditionAsthma
PhasePhase 3
StatusCompleted
AllocationRandomized
Design modelParallel
MaskingTriple
Primary purposeTreatment
Enrollment210
Lead sponsorSanofi
StartOctober 15, 2015
Primary completionSeptember 20, 2017

2. Clinical Question

The primary clinical question was whether treatment with dupilumab 300 mg every 2 weeks, compared with placebo every 2 weeks, produced a greater reduction from baseline in OCS dose at Week 24 while maintaining asthma control.

Population

Patients with severe steroid-dependent asthma enrolled in the phase 3 VENTURE trial.

Intervention

Dupilumab 300 mg every 2 weeks, alongside the background therapies specified in the registry.

Comparator

Placebo every 2 weeks, alongside the background therapies specified in the registry.

Primary question

Does dupilumab produce a greater percentage reduction in OCS dose at Week 24 while maintaining asthma control?

3. Trial Design

01
Randomize210 participants
02
AssignDupilumab or placebo
03
TreatEvery 2 weeks
04
AssessWeek 24 OCS outcomes
05
AnalyzeITT population
ARM A · DUPILUMAB 300 MG Q2W · n = 103

Dupilumab

  • Dupilumab 300 mg every 2 weeks
  • Background oral corticosteroid therapy
  • Inhaled corticosteroid therapy
  • Albuterol/Salbutamol or Levalbuterol/Levosalbutamol as registered interventions
ARM B · PLACEBO Q2W · n = 107

Placebo

  • Placebo every 2 weeks
  • Background oral corticosteroid therapy
  • Inhaled corticosteroid therapy
  • Albuterol/Salbutamol or Levalbuterol/Levosalbutamol as registered interventions
Allocation
Randomized allocation to two parallel treatment groups.
Masking
Triple masking was specified in the registry.
Primary purpose
Treatment of severe steroid-dependent asthma.
Analysis framework
Primary efficacy analysis used the intent-to-treat population.

4. Endpoints

EndpointTime frameRegistry definition / analysis
Percentage Reduction From Baseline in Oral Corticosteroids (OCS) Dose at Week 24 While Maintaining Asthma Control Baseline, Week 24 Percentage reduction calculated as (optimized OCS dose at baseline − final OCS dose at Week 24) / optimized OCS dose at baseline × 100. Result presented as LS Mean (SE) percentage reduction from baseline derived from an ANCOVA model with missing data multiply imputed.
Supplementary Presentation of Primary Outcome Measure Data: Median Percentage Reduction From Baseline in Oral Corticosteroids Dose at Week 24 While Maintaining Asthma Control Baseline, Week 24 Supplementary presentation of the primary outcome measure, reported as median (inter-quartile range).
Percentage of Participants Achieving ≥50% Reduction in Oral Corticosteroids Dose at Week 24 While Maintaining Asthma Control Week 24 Binary outcome analyzed using logistic regression in the ITT population.
Percentage of Participants Achieving a Reduction in Oral Corticosteroids Dose to <5 mg/Day at Week 24 While Maintaining Asthma Control Week 24 Binary outcome analyzed using logistic regression in the ITT population.
Percentage of Participants Achieving Maximum Possible Reduction in Oral Corticosteroids Dose Per Protocol at Week 24 While Maintaining Asthma Control Week 24 Binary outcome analyzed using logistic regression in the ITT population; per-protocol reduction criterion is part of the endpoint definition.
Percentage of Participants Who No Longer Required Oral Corticosteroids Dose at Week 24 While Maintaining Asthma Control Week 24 Binary outcome analyzed using logistic regression in the ITT population with baseline OCS dose less than or equal to 30 mg/day.

The registry lists 2 primary endpoints, with the second described as a supplementary presentation of the primary outcome measure. The posted formal primary analysis is for the LS-mean percentage reduction endpoint; the supplementary median presentation does not have a separate formal statistical comparison in the ClinicalTrials.gov record.

5. Statistical Methodology

Primary ANCOVA analysis

The primary endpoint was analyzed using analysis of covariance (ANCOVA). The response variable was percentage reduction in OCS dose at Week 24. The model included treatment group, baseline eosinophil level, optimized OCS dose at baseline, and region as covariates.

Conceptual ANCOVA structure
Y = β0 + β1(Treatment) + β2(Baseline eosinophil) + β3(Baseline OCS) + β4(Region) + ε

The treatment coefficient represents the adjusted difference between randomized treatment groups after accounting for the covariates specified in the registry analysis.

Logistic regression for binary secondary endpoints

Four posted secondary analyses evaluated whether participants achieved clinically defined OCS-reduction milestones. Each was modeled using logistic regression, with treatment group and specified baseline covariates included in the model.

Conceptual logistic model
logit[P(Y=1)] = β0 + β1(Treatment) + β2(Baseline OCS) + β3(Region) + β4(Eosinophil subgroup)

For these analyses, the exponentiated treatment coefficient is expressed as an odds ratio comparing dupilumab with placebo.

Intention-to-treat analysis

The primary and posted secondary efficacy analyses were conducted in the intent-to-treat (ITT) population. The registry describes this as the randomized population analyzed according to the treatment group allocated by randomization, regardless of whether treatment was received as planned.

Covariate adjustment

Covariate adjustment is especially relevant here because the primary endpoint is a continuous percentage reduction rather than a simple unadjusted treatment-group difference. The ANCOVA model incorporates baseline OCS dose, baseline eosinophil level, and region in the treatment comparison. The secondary logistic models similarly adjust for prespecified baseline characteristics.

Missing data and multiple imputation

The registry states that missing data were imputed using a pattern mixture model by multiple imputation. This means the analysis did not simply discard participants with missing Week 24 information. Instead, missing outcomes were handled through an explicit imputation framework before the statistical comparison was made.

Why this matters: an imputed analysis depends on assumptions about the relationship between observed and unobserved outcomes. The reported treatment estimate therefore reflects both the observed data and the specified missing-data strategy. Multiple imputation does not make missing information disappear; it provides a model-based way to incorporate uncertainty about it.

6. Multiplicity and Hierarchical Testing

The registry analysis notes state that a hierarchical testing procedure was used to control the overall type I error. Testing proceeded sequentially in the order the outcome measures were reported and continued when the previous outcome measure was statistically significant at a two-sided 0.05 level.

Why hierarchy matters

Multiple hypothesis tests can increase the chance of a false-positive conclusion if treated as unrelated tests. A prespecified hierarchy provides an ordered framework for determining which subsequent hypotheses can be formally tested.

What the p-values mean here

The reported p-values should be interpreted in the context of this sequential testing strategy rather than as isolated numbers detached from the endpoint hierarchy.

The registry specifically states that the hierarchical procedure continued for the secondary endpoints only when the previous endpoint was statistically significant. This is a different concept from simply declaring every posted p-value independently significant or nonsignificant.

7. Results

Primary endpoint: percentage reduction in OCS dose

The primary formal analysis compared the placebo q2w group with the dupilumab 300 mg q2w group using ANCOVA in the ITT population. The treatment comparison was expressed as a least-squares mean difference.

Adjusted difference in percentage reduction from baseline

28.24

95% CI: 15.81–40.67   ·   P < 0.0001

Effect measure: Least Square Mean Difference  ·  Two-sided 95% CI  ·  Superiority

Primary analysis componentReported result
Groups comparedPlacebo q2w vs Dupilumab 300 mg q2w
Analysis populationIntent-to-treat population
MethodANCOVA
Effect measureLeast Square Mean Difference
Estimate28.24
95% confidence interval15.81–40.67
P-value< 0.0001
Hypothesis typeSuperiority
Missing-data approachPattern mixture model by multiple imputation
Clinical Biostats interpretation

The estimated LS mean difference of 28.24 indicates that the model-estimated percentage reduction in OCS dose was 28.24 percentage points greater for the dupilumab group than for the placebo group, after adjustment for baseline eosinophil level, optimized OCS dose at baseline, and region.

This is an adjusted mean difference, not an odds ratio, relative risk, or probability that an individual patient will achieve a particular OCS reduction. It also does not mean that every patient experienced a 28.24-percentage-point additional reduction.

The 95% CI of 15.81–40.67 describes uncertainty around the estimated adjusted treatment difference under the specified ANCOVA and missing-data framework. It is not an interval containing 95% of individual patient treatment effects.

The p-value < 0.0001 provides evidence against the null hypothesis used for this superiority comparison under the specified statistical framework. A p-value does not measure the magnitude of the treatment effect and does not indicate the probability that the null hypothesis is true.

Because the endpoint was analyzed with missing data multiply imputed under a pattern mixture model, the estimate also depends on the assumptions used to construct the imputed values. The treatment comparison should therefore be understood as a model-based ITT estimate rather than a simple calculation from complete cases alone.

Supplementary presentation of the primary endpoint

The registry also reports a supplementary presentation of the same primary outcome measure as a median percentage reduction from baseline at Week 24 while maintaining asthma control. The registry identifies this as a supplementary presentation and does not provide a separate formal statistical analysis for the median in the ClinicalTrials.gov record.

Statistical distinction: the posted formal primary result is the LS mean difference from ANCOVA. The median is a descriptive presentation of the same outcome measure. A median and an adjusted LS mean answer related but different statistical questions, so they should not be substituted for one another.

8. Secondary Endpoint Results

At least 50% reduction in OCS dose

The first posted secondary analysis evaluated the percentage of participants achieving a ≥50% reduction in OCS dose at Week 24 while maintaining asthma control. The ITT population was analyzed using logistic regression.

Odds ratio for achieving ≥50% OCS reduction

3.98

95% CI: 2.06–7.67   ·   P < 0.0001

Two-sided 95% CI  ·  Superiority

Clinical Biostats interpretation

An odds ratio of 3.98 means the estimated odds of achieving the ≥50% OCS-reduction criterion were 3.98 times as high in the dupilumab group as in the placebo group, after adjustment for the covariates specified in the logistic model.

The odds ratio is not a probability ratio. An OR of 3.98 cannot be read as saying that the probability of success was 3.98 times higher without knowing the underlying probabilities.

The 95% CI of 2.06–7.67 quantifies uncertainty around the estimated odds ratio. It does not describe the range of responses experienced by individual participants.

The p-value < 0.0001 addresses evidence against the null comparison under the specified model and testing framework. It does not indicate how large or clinically important the observed effect is.

Reduction of OCS dose to <5 mg/day

A second posted secondary endpoint evaluated the percentage of participants achieving a reduction in OCS dose to <5 mg/day at Week 24 while maintaining asthma control.

Odds ratio for achieving OCS dose <5 mg/day

4.48

95% CI: 2.39–8.39   ·   P < 0.0001

Two-sided 95% CI  ·  Superiority

Clinical Biostats interpretation

The estimated odds ratio of 4.48 indicates higher estimated odds of reaching the registered <5 mg/day OCS criterion in the dupilumab group than in the placebo group, based on the adjusted logistic regression model.

The estimate should not be interpreted as a 348% increase in probability. Odds and probabilities are related mathematically, but they are not interchangeable measures.

The 95% CI of 2.39–8.39 indicates statistical uncertainty around the odds-ratio estimate. The interval remains above 1, consistent with a positive treatment-group contrast under the model.

The reported p-value < 0.0001 is evidence against the null hypothesis for this sequentially tested endpoint; it is not itself an effect-size measure.

Maximum possible OCS reduction per protocol

The third posted secondary analysis evaluated the percentage of participants achieving the maximum possible reduction in OCS dose per protocol at Week 24 while maintaining asthma control.

Odds ratio for maximum possible OCS reduction

2.57

95% CI: 1.4–4.73   ·   P = 0.0024

Two-sided 95% CI  ·  Superiority

Clinical Biostats interpretation

An odds ratio of 2.57 indicates that the estimated odds of achieving the maximum possible protocol-defined OCS reduction were 2.57 times those in the placebo group under the adjusted logistic regression model.

The confidence interval, 1.4–4.73, is wider than would be implied by a highly precise estimate and therefore matters when interpreting the magnitude of the effect. It describes uncertainty around the model-based odds ratio rather than individual patient outcomes.

The p-value of 0.0024 provides evidence against the null comparison under the stated testing framework. It should not be used as a substitute for the effect estimate or its confidence interval.

The registry notes that this endpoint was part of the hierarchical testing sequence. Consequently, its inferential interpretation depends on the preceding endpoint having met the criterion required for continuation of the hierarchy.

No longer requiring OCS

The fourth posted secondary analysis evaluated the percentage of participants who no longer required an OCS dose at Week 24 while maintaining asthma control. The analysis population was the ITT population with baseline OCS dose less than or equal to 30 mg/day.

Odds ratio for no longer requiring OCS

2.74

95% CI: 1.47–5.1   ·   P = 0.0015

Two-sided 95% CI  ·  Superiority

Clinical Biostats interpretation

The odds ratio of 2.74 indicates that the estimated odds of no longer requiring OCS at Week 24 were 2.74 times as high in the dupilumab group as in the placebo group among the specified analysis population.

The restriction to participants with baseline OCS dose less than or equal to 30 mg/day is important. This is not the same analysis population as an unrestricted ITT analysis, so its estimate should not be generalized automatically to every randomized participant.

The 95% CI of 1.47–5.1 expresses uncertainty around the adjusted odds-ratio estimate. The p-value of 0.0015 addresses statistical evidence under the specified logistic model and hierarchical testing framework, not effect magnitude or individual probability of success.

9. Results Summary

EndpointMethodEffect95% CIP-value
Primary: percentage reduction from baseline in OCS dose at Week 24 while maintaining asthma control ANCOVA LS mean difference 28.24 15.81–40.67 < 0.0001
≥50% reduction in OCS dose Logistic regression OR 3.98 2.06–7.67 < 0.0001
OCS dose <5 mg/day Logistic regression OR 4.48 2.39–8.39 < 0.0001
Maximum possible OCS reduction per protocol Logistic regression OR 2.57 1.4–4.73 0.0024
No longer requiring OCS, baseline OCS ≤30 mg/day Logistic regression OR 2.74 1.47–5.1 0.0015

The statistical pattern is internally coherent: the primary continuous endpoint and the posted binary secondary endpoints all estimate treatment contrasts favoring the dupilumab group under their respective models. However, the effect measures are not directly interchangeable. The ANCOVA result is an adjusted difference in mean percentage reduction, whereas the secondary results are adjusted odds ratios for achieving specific binary milestones.

10. How to Read the Primary Effect Estimate

Difference in adjusted means

The primary estimate of 28.24 is a difference in adjusted mean percentage reduction. If the two treatment groups had identical covariate profiles under the fitted model, the estimated difference in their mean percentage reductions would be 28.24 percentage points.

Confidence interval

The 95% CI of 15.81–40.67 provides a range of values compatible with the estimated treatment difference under the model and sampling assumptions. A confidence interval is therefore more informative about precision than the p-value alone.

P-value

The p-value < 0.0001 quantifies how incompatible the observed result would be with the null hypothesis under the specified statistical model. It does not tell us the probability that dupilumab works, the probability that the effect is clinically important, or the percentage of patients who benefit.

Adjusted versus unadjusted

The estimate is not simply the difference between two raw group means. ANCOVA uses the specified baseline covariates to produce a model-adjusted treatment comparison. This can improve precision and account for prognostic baseline information, provided the model is appropriate.

11. How to Read the Odds Ratios

Odds ratioRegistered endpointStatistical meaning
3.98≥50% OCS reductionEstimated odds of meeting the binary criterion were 3.98 times those in the placebo group.
4.48OCS dose <5 mg/dayEstimated odds of meeting the <5 mg/day criterion were 4.48 times those in the placebo group.
2.57Maximum possible OCS reductionEstimated odds of meeting the protocol-defined maximum reduction criterion were 2.57 times those in the placebo group.
2.74No longer requiring OCSEstimated odds of no longer requiring OCS were 2.74 times those in the placebo group within the specified analysis population.

These four odds ratios describe different binary outcomes. They should not be combined into a single summary statistic or treated as interchangeable measures of treatment effect. Each one answers a separate question about OCS reduction.

12. Statistical Methods Explained

Why was ANCOVA used for the primary endpoint?

The primary endpoint is a continuous percentage reduction from baseline. ANCOVA provides a framework for comparing treatment groups while adjusting for prespecified baseline covariates. Here, the registry specifies baseline eosinophil level, optimized OCS dose at baseline, and region as covariates in addition to treatment group.

What does an LS mean difference of 28.24 mean?

It is the model-adjusted difference between the treatment-group least-squares means for percentage reduction in OCS dose. A value of 28.24 means the estimated adjusted percentage reduction was 28.24 percentage points greater in the dupilumab group than in the placebo group. It is not a percentage probability and not a relative risk.

Why use logistic regression for the secondary endpoints?

Each of these endpoints converts the clinical outcome into a binary status: for example, whether a participant achieved at least a 50% OCS reduction. Logistic regression models the probability of that binary outcome and expresses the treatment contrast as an odds ratio.

What does an odds ratio of 3.98 mean?

An odds ratio of 3.98 means the estimated odds of achieving the specified ≥50% OCS reduction were 3.98 times higher in the dupilumab group than in the placebo group, after the model's covariate adjustment. It does not mean that the probability of success was 398% or that the probability itself was multiplied by 3.98.

Why does missing-data imputation matter?

The primary endpoint requires a Week 24 OCS dose. When that information is missing, the observed dataset alone cannot directly provide the participant's unobserved outcome. The registry specifies a pattern mixture model using multiple imputation, so the reported analysis incorporates modeled values for missing observations. Different assumptions about missing outcomes can produce different estimates.

Why does ITT analysis matter?

The ITT principle keeps participants associated with the randomized treatment group for efficacy analysis. This preserves the treatment comparison created by randomization and avoids redefining treatment groups according to what participants subsequently received.

Why does the hierarchical testing procedure matter?

The registry states that testing proceeded sequentially and continued only when the preceding outcome was statistically significant at a two-sided 0.05 level. This controls the overall type I error across the prespecified sequence more effectively than treating every endpoint as an independent hypothesis test.

13. Secondary Analysis: Per-Protocol Criterion Within an ITT Analysis

One of the secondary endpoints is explicitly defined as achievement of the maximum possible reduction in OCS dose per protocol. Importantly, the registry states that the statistical analysis itself was performed in the ITT population.

These concepts should not be confused. "Per protocol" describes the criterion used to define the maximum possible OCS reduction endpoint. It does not mean that the posted logistic regression was performed only among participants who complied with the protocol. The ClinicalTrials.gov record explicitly identifies the analysis population as ITT.

This distinction is statistically important. A per-protocol analysis population can differ from an endpoint whose definition references protocol-based treatment rules. Here, the registry's analysis population remains ITT while the endpoint itself incorporates a protocol-defined maximum reduction.

14. Safety Results

The ClinicalTrials.gov record reports serious adverse events by randomized treatment arm. These are presented as affected participants over participants at risk.

Safety measurePlacebo q2wDupilumab 300 mg q2w
Serious adverse events6/1079/103
Serious adverse events: affected / at risk
Placebo q2w
6/107
Dupilumab 300 mg q2w
9/103

The ClinicalTrials.gov record does not provide a formal statistical comparison for serious adverse events. Accordingly, the counts are descriptive rather than a reported inferential test of safety differences.

Interpretation caution: the denominators differ between the two randomized groups. The displayed 6/107 and 9/103 figures should therefore be read as affected participants among those at risk in each arm, not simply as raw event counts.

15. Trial Timeline

October 15, 2015

Trial start

The VENTURE phase 3 study began.

2015–2017

Randomized treatment period

The study evaluated dupilumab 300 mg q2w versus placebo q2w in the randomized parallel-group design.

September 20, 2017

Primary completion

The registry lists September 20, 2017 as the primary completion date.

Completed

Results posted

The registry is marked completed and contains 14 posted outcome measures and 5 posted statistical analyses.

16. What the Trial's Statistical Evidence Shows

Continuous endpoint

The primary ANCOVA estimated a 28.24 percentage-point adjusted difference in OCS dose reduction, with a 95% CI of 15.81–40.67 and p < 0.0001.

Binary milestones

Four secondary endpoints used logistic regression and reported odds ratios of 3.98, 4.48, 2.57, and 2.74.

Missing data

The primary analysis used a pattern mixture model by multiple imputation rather than a complete-case-only approach.

Multiplicity

The registry describes hierarchical testing, with sequential testing continuing when the preceding outcome was statistically significant at a two-sided 0.05 level.

17. Limitations

18. Why This Trial Matters Statistically

VENTURE is a useful teaching case because it illustrates how a clinical trial can use different statistical models for closely related versions of the same clinical question. The primary endpoint is continuous and therefore uses ANCOVA, while several secondary endpoints convert OCS reduction into clinically defined binary milestones and use logistic regression.

Statistical conceptHow it appears in VENTURE
RandomizationRandomized parallel-group phase 3 design with 210 enrolled participants.
BlindingTriple masking was specified.
Intention-to-treatPrimary and posted secondary efficacy analyses were conducted in the ITT population.
ANCOVAUsed for the primary percentage reduction in OCS dose endpoint.
Covariate adjustmentPrimary model included baseline eosinophil level, optimized OCS dose at baseline, and region.
Logistic regressionUsed for binary OCS-reduction milestones.
Odds ratioReported treatment effect for the binary secondary endpoints.
Multiple imputationMissing data handled using a pattern mixture model by multiple imputation.
MultiplicityHierarchical testing used for sequential endpoint testing.
Per-protocol conceptOne secondary endpoint used a protocol-defined maximum possible OCS reduction while retaining an ITT analysis population.
Confidence intervals95% two-sided intervals reported for the primary LS mean difference and secondary odds ratios.
Safety analysisSerious adverse events reported descriptively by randomized arm.

19. Clinical Interpretation vs Statistical Interpretation

Statistical interpretation

The primary ANCOVA estimated a positive adjusted difference in percentage reduction in OCS dose, with a 95% CI of 15.81–40.67 and p < 0.0001. The posted binary secondary analyses also produced odds ratios above 1 with their reported two-sided confidence intervals and p-values.

Clinical interpretation

The endpoint framework focuses on reducing exposure to oral corticosteroids while maintaining asthma control. The trial therefore evaluates both the magnitude of continuous OCS reduction and the proportion of participants reaching specific OCS-reduction milestones.

The statistical evidence should be read at the level of the endpoint being analyzed. A 28.24 percentage-point adjusted difference, an odds ratio of 3.98, and an odds ratio of 4.48 are not different ways of expressing the same numerical quantity. They represent different estimands arising from different outcome definitions and models.

20. A Deeper Look at Missing Data

The primary endpoint requires a final OCS dose at Week 24. Missing Week 24 information can therefore affect the calculation of percentage reduction. The registry explicitly states that missing data were handled using a pattern mixture model with multiple imputation.

Primary endpoint calculation
Percentage reduction = [(Optimized OCS dose at baseline − Final OCS dose at Week 24) / Optimized OCS dose at baseline] × 100

The statistical analysis then modeled this percentage reduction using ANCOVA after the specified missing-data procedure.

This is important because the final analysis is not merely a calculation performed independently for every participant with complete data. The analysis combines the endpoint definition, the covariate-adjusted ANCOVA model, and the missing-data assumptions into a single inferential framework.

For educational purposes, this also illustrates why two analysts can use the same randomized trial and obtain different results if they make materially different assumptions about missing outcomes. The appropriate comparison is therefore not only the numerical estimate but also the estimand, analysis population, model, and missing-data strategy.

21. Confidence Intervals Across the Reported Analyses

EffectEstimate95% CIWhat the interval describes
Primary LS mean difference28.2415.81–40.67Uncertainty around the adjusted difference in percentage reduction.
≥50% OCS reduction OR3.982.06–7.67Uncertainty around the adjusted odds ratio.
OCS dose <5 mg/day OR4.482.39–8.39Uncertainty around the adjusted odds ratio.
Maximum possible OCS reduction OR2.571.4–4.73Uncertainty around the adjusted odds ratio.
No longer requiring OCS OR2.741.47–5.1Uncertainty around the adjusted odds ratio in the specified analysis population.

Confidence intervals are especially useful for comparing the precision of estimates. The width of an interval reflects statistical uncertainty, whereas the location of the interval describes the range of effect estimates compatible with the analysis framework.

22. The Role of the Analysis Population

The registry's repeated use of the ITT population is a major component of the inferential structure. Participants remain classified according to their randomized assignment for efficacy analyses. This maintains the comparison generated by randomization.

The OCS-withdrawal endpoint illustrates why population definitions must always be read alongside effect estimates. Although the analysis remains ITT, it is explicitly restricted to participants whose baseline OCS dose was less than or equal to 30 mg/day. Its odds ratio therefore answers a narrower question than the primary endpoint.

General statistical lesson: an effect estimate without its analysis population is incomplete. Two odds ratios can have identical numerical values while answering materially different questions if their populations or endpoint definitions differ.

23. Why the Endpoint Hierarchy Matters

The registry describes a sequence in which testing continued only when the previous endpoint was statistically significant at a two-sided 0.05 level. This creates a chain of inferential claims rather than four unrelated secondary tests.

01
PrimaryOCS % reduction
02
Secondary≥50% reduction
03
Secondary<5 mg/day
04
SecondaryMaximum reduction
05
SecondaryNo longer requiring OCS

The hierarchy does not make the endpoints equivalent. Rather, it determines how evidence can propagate through the prespecified testing sequence. This is a central distinction between multiplicity control and simply counting how many p-values are below a threshold.

24. Important Statistical Takeaways

Estimate first

The treatment effect should be understood from its effect measure and magnitude before looking at the p-value.

Precision matters

The confidence interval communicates how precisely the trial estimated the treatment contrast.

Model matters

ANCOVA and logistic regression answer different statistical formulations of the treatment question.

Missingness matters

The primary estimate incorporates a pattern mixture multiple-imputation strategy for missing data.

25. Related Tutorials

Learn more about the methods used in this trial:

26. Related Calculators

27. Sources

Continue through the Clinical Biostats statistical library

Explore the statistical methods behind randomized clinical trials, from covariate-adjusted models and logistic regression to confidence intervals and missing-data methods.

28. Record Summary

VENTURE provides a compact example of how randomized clinical-trial evidence can be analyzed at several levels. The primary endpoint uses ANCOVA to estimate an adjusted difference in percentage reduction in OCS dose, while binary OCS-reduction milestones use logistic regression and odds ratios. The ClinicalTrials.gov record also explicitly document ITT analysis, covariate adjustment, pattern mixture multiple imputation, and a hierarchical testing procedure.

The primary formal estimate was an LS mean difference of 28.24, with a two-sided 95% CI of 15.81–40.67 and p < 0.0001. The four posted secondary binary analyses reported odds ratios of 3.98, 4.48, 2.57, and 2.74, respectively, with their corresponding confidence intervals and p-values. Serious adverse events were reported descriptively as 6/107 for placebo q2w and 9/103 for dupilumab 300 mg q2w.

Clinical Biostats methodology: The statistical story of a trial is more than its p-values. A complete interpretation considers the estimand, endpoint definition, analysis population, model, covariate adjustment, missing-data strategy, confidence interval, multiplicity framework, and the distinction between statistical evidence and clinical interpretation.