Follow-up of the VIPES Study to Evaluate Efficacy and Safety of Viaskin Peanut in Adults and Children: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Follow-up of the VIPES Study to Evaluate Efficacy and Safety of Viaskin Peanut in Adults and Children (NCT01955109), a na phase 2 study. The primary outcome is Percentage of Treatment Responders at Months 12 and 24.

2. Clinical Question

3. Trial Design

This was an open-label follow-up study of participants who had previously been randomized and completed VIPES. The record classifies the study as Phase 2 and as a single-group study, with no allocation and no masking. Participants received Viaskin Peanut 250 mcg. The follow-up was intended to examine efficacy and safety over longer treatment, as well as sustained unresponsiveness after treatment stopped for a period among participants who had become desensitized.

The record lists an enrollment of 171 and a completed study status. The recorded start and primary completion dates are 2013-09 and 2016-09. These dates describe the study record; they do not by themselves establish how long an individual participant remained in follow-up or received treatment.

Although the primary endpoint results were organized by the treatment participants received in VIPES, that earlier assignment does not make this follow-up a randomized comparison. All participants in the follow-up received Viaskin Peanut, and the record identifies no concurrent untreated or placebo group. The prior-treatment categories can describe the history of the enrolled participants, but differences between them during follow-up cannot be interpreted as if treatment had been newly assigned at random in this study.

The primary endpoint was the percentage of participants meeting a responder definition at Month 12 and Month 24. The record describes different cumulative active-treatment durations at these assessments according to prior VIPES assignment: participants who had received Viaskin Peanut in VIPES had received 24 months of active treatment at Month 12 and 36 months at Month 24; those who had received placebo in VIPES had received 12 months and 24 months, respectively. These durations are part of the endpoint description, not evidence of a randomized duration comparison within the follow-up.

The registry lists one primary outcome and seven secondary outcomes, including food-challenge response, cumulative reactive dose, peanut-specific antibody measures, and skin-prick-test wheal diameter. The registry record does not report the detailed protocol, a sample-size justification, or the statistical analysis plan. The study’s stated objectives and outcome list therefore describe what it set out to evaluate, but do not fill in unreported design or analysis details.

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 who received 50, 100 or 250 micrograms (μg) Viaskin Peanut in VIPES continued on same dose in OLFUS-VIPES; those receiving placebo were re-randomized 1:1:1 to 50, 100 or 250 μg Viaskin Peanut. After protocol amendment 1, all participants received 250 μg dose from start of OLFUS-VIPES; those already enrolled were switched to 250 μg at Month 6 visit.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The full analysis set was the intent-to-treat population which consisted of all participants and results are reported for those participants who had the Months 12 and 24 DBPCFC performed.

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: The safety analysis set included all participants who received at least 1 dose of investigational product (IP) during the OLFUS-VIPES study.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Treatment Responders at Months 12 and 24, measured over Month 12 and Month 24 (end of treatment) of the OLFUS-VIPES study.

The primary endpoint is the percentage of participants classified as treatment responders at Month 12 and Month 24. Response was determined by a double-blind, placebo-controlled food challenge. A participant met the definition if the peanut protein eliciting dose was at least 1000 mg, or if it had increased at least 10-fold compared with the initial eliciting dose observed at VIPES baseline. The definition therefore allows either an absolute threshold or a relative increase to qualify.

A percentage is a binary-outcome summary: each assessed participant is classified as meeting or not meeting the responder definition, and the proportion meeting it is expressed as a percentage. In general, this kind of endpoint makes a clinical threshold easier to interpret than a continuous change alone, but the classification depends on the chosen threshold and on having an evaluable food-challenge assessment.

The endpoint uses food challenge because the outcome is based on the amount of peanut protein that elicits a response during the challenge, rather than on a laboratory measure alone. The registry specifies the assessment method and the two follow-up timepoints, but does not provide the observed percentages, confidence intervals, or the numbers assessed at each timepoint. Consequently, the endpoint’s definition can be described, but its observed magnitude and precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a binary classification summarized as a percentage. Each participant with an applicable food-challenge assessment either meets the responder definition or does not. In this study, the positive classification is based on a peanut protein eliciting dose of at least 1000 mg, or an increase of at least 10-fold from the initial eliciting dose observed at VIPES baseline. This combines an absolute criterion with a criterion relative to an individual’s baseline.

For a binary endpoint, the percentage is the proportion of assessed participants classified as responders, expressed on a percentage scale. The denominator is important: it is the number of participants included in the relevant analysis at the specified timepoint, not automatically the full enrollment. The registry says the results are reported for participants who had the Month 12 and Month 24 food challenges performed, but does not report the number assessed or the observed percentages. No new percentage can be derived from the record.

The endpoint lists a 95% confidence interval as its dispersion measure. In general, a confidence interval communicates uncertainty around an estimated percentage. It reflects how much the estimate might vary across samples under the statistical method’s assumptions. The interval’s width depends in part on the amount of information in the data, including the number assessed and the distribution of outcomes. Because the interval limits and assessment counts are not reported in the registry record, neither the uncertainty around the response estimates nor the precision at each timepoint can be evaluated.

The primary endpoint was assessed at two timepoints. Repeated assessment can describe how response status is reported at different stages of follow-up, but results at different times are not necessarily independent: the same participants may contribute assessments at both times. A statistical comparison across time would need to account for the analysis question and the relationship between repeated measurements. The registry record does not report such a comparison or its method. The two timepoints are specified as endpoint assessments, not as evidence of a particular longitudinal model.

The record also describes the endpoint by prior VIPES treatment. At Month 12, participants who had received Viaskin Peanut in VIPES had received 24 months of active treatment, while those who had received placebo in VIPES had received 12 months. At Month 24, the corresponding durations were 36 months and 24 months. These differences are relevant context when reading any group-specific response result. Since the follow-up itself was open-label and single-group, these categories are not randomized concurrent treatment groups for estimating a treatment effect within this study.

For this kind of percentage outcome, a comparison between groups would generally require a defined estimand, a specified analysis population, a method for handling missing observations, and an uncertainty measure for the contrast. In general, a statistical test addresses whether the data are inconsistent with a specified null model, while an effect estimate and confidence interval describe the magnitude and precision of a contrast. The registry record does not report a treatment contrast, test statistic, p-value, or analysis method for the primary endpoint. It therefore does not support a formal comparative inference from the posted endpoint description.

The record describes the full analysis set as the intent-to-treat population consisting of all participants, but says the reported results are for participants with the Month 12 and Month 24 food challenges performed. In general, intent-to-treat analysis refers to analyzing participants according to their assigned group in a randomized study, regardless of adherence or treatment changes. Here, the registry uses that term to define the population, but also narrows the reported results to participants with completed assessments. How those two descriptions were operationalized, and whether missing assessments were imputed or excluded, are not reported in the registry record.

Missing outcome data can affect a percentage when the likelihood of having an assessment differs according to participants’ characteristics or outcomes. In general, complete-case results describe those with observed measurements; they need not represent everyone enrolled if assessment completion is selective. This is a general statistical concern, not a claim that selection occurred in this study. The registry does not report the number missing at either timepoint, reasons for missingness, or sensitivity analyses that could assess the influence of missing data.

Multiplicity is a general concern when investigators examine several outcomes, timepoints, or group-specific comparisons. More analyses can increase the chance of observing an apparently notable result by chance if no adjustment or hierarchy is used. The registry lists the primary outcome at two timepoints and several secondary measures, but does not report a multiplicity strategy or identify which comparisons, if any, were confirmatory. Therefore, the relative inferential status of potential findings cannot be established from the record.

Sample-size planning is different from analysis of observed outcomes. The record describes a planning illustration using a two-sided significance level of 0.05, equal allocation, a normal approximation, and a target effect defined as a stated fraction of the observed effect. In general, such calculations estimate how many participants might be needed under specified assumptions; they do not tell whether an observed effect is statistically persuasive, and they are not observed power. The original trial’s sample-size justification and any protocol-level assumptions are not reported in the registry record. No conclusions about the trial’s design adequacy can be drawn from an illustration alone.

Over-dispersion is a general statistical issue for count data when the observed variability exceeds what a simple model assumes. It is less central to interpreting the primary binary percentage itself than to some count or rate analyses, but it can matter for secondary outcomes if those are analyzed using count models. The registry record does not report an analysis of that kind or any model diagnostics. This general point does not imply that over-dispersion occurred in this study.

Finally, the registry lists zero analyses. That means the record does not supply analysis-level estimates or tests to interpret for the outcomes listed. It still provides endpoint definitions, follow-up timing, study design details, and selected adverse-event counts. Those details support an explanation of what was planned and how particular results would be read, but they cannot substitute for the unreported efficacy estimates or statistical analysis plan.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome assessed at Month 12 and Month 24, as well as seven secondary outcomes spanning food-challenge response, cumulative reactive dose, immunoglobulin measures, and skin-prick testing. Evaluating several outcomes and timepoints raises a general multiplicity question: without a prespecified testing hierarchy or adjustment, the chance of at least one apparently unusual result can increase when many statistical tests are considered. The registry record does not report a multiplicity adjustment, testing hierarchy, or which analyses were intended to be confirmatory.

The record identifies the full analysis set as the intent-to-treat population consisting of all participants, but describes reported primary endpoint results as applying to participants who had the Month 12 and Month 24 food challenges performed. It does not report how many participants had each assessment, whether results required completion of both assessments, or how missing measurements were handled. Imputation methods, sensitivity analyses, and reasons for missing assessments are not reported in the registry record.

In general, missing-data handling matters because the observed participants may differ from those without measurements. A percentage calculated only among participants with an available assessment describes that observed subset; interpreting it as representative of everyone enrolled depends on assumptions about missingness. This is a general issue, not evidence that missingness biased the study’s results.

The registry lists zero analyses and does not report the statistical analysis plan. As a result, the intended handling of multiplicity, missing data, analysis populations, and any adjusted or subgroup analyses cannot be established. These gaps limit the interpretation of any unreported estimates as well as the reproducibility of the analysis.

11. 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: food allergy (2.1%), appendicitis (2.1%), clavicle fracture (2.1%), joint dislocation (2.1%), anaphylactic reaction (1.6%).

The registry reports serious adverse events by prior VIPES treatment group. In the group titled VIPES Initial Treatment Group: All Viaskin Peanut Doses, 7 of 123 participants were affected by serious adverse events; in the VIPES Initial Treatment Group: Placebo group, 3 of 48 were affected. The record reports zero deaths in each group. It also reports other adverse events affecting 113 of 123 participants and 47 of 48 participants, respectively.

The listed serious-event terms include Food allergy, Appendicitis, Clavicle fracture, and Joint dislocation, each reported as 2.1%; Anaphylactic reaction, reported as 1.6%; and Crohn's disease, reported as 0.8%. These are registry-listed terms and percentages. The record does not provide further event-level details in the registry record, such as timing, duration, outcome, or individual attribution.

These counts describe events recorded during the follow-up, not a randomized safety comparison. The groups reflect prior VIPES treatment, and the follow-up itself was open-label with no newly randomized comparator. Differences in the counts should not be interpreted as causal treatment effects. Counts also do not, by themselves, establish the rate of events over a common duration of exposure. The registry record does not provide person-time or enough detail to make that comparison.

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

The registry record establishes the question the follow-up set out to address: whether participants met a food-challenge-based responder definition at Month 12 and Month 24, alongside longer-term safety and other outcome assessments. It also specifies how a responder was classified and the treatment durations associated with prior VIPES assignment at each assessment. These details allow the endpoint and study context to be understood.

The record does not report the primary endpoint percentages or their 95% confidence intervals. It therefore cannot establish the observed proportion meeting the responder definition, or how precise that estimate was. The absence of reported estimates is not evidence that the outcome was favorable, unfavorable, or unchanged. It means those conclusions cannot be drawn from the registry record.

The follow-up is not a new randomized comparison. Participants received Viaskin Peanut, and the primary results were categorized according to prior VIPES treatment. The prior-treatment groups had different cumulative active-treatment durations during follow-up. Even if group-specific outcome values were available, their contrast would need cautious interpretation and would not automatically represent the effect of treatment assignment in this follow-up.

The listed adverse-event counts describe the safety information recorded, including serious events, other events, and deaths. They do not on their own establish whether treatment caused an event or permit a controlled comparison. The registry record does not report a concurrent randomized comparator or person-time details for interpreting event rates.

In general, a trial outcome is most informative when its estimate, uncertainty, analysis population, and missing-data handling are available together. Here, the endpoint definition and selected safety counts are reported, but the primary efficacy estimates, statistical tests, analysis plan, and important missing-data details are not reported in the registry record. The study’s stated objectives should therefore be distinguished from what can be concluded from the recorded results.

13. Why This Trial Matters Statistically

This follow-up illustrates why study design and analysis populations matter as much as endpoint definitions. A responder percentage sounds straightforward, but it depends on who completed the food challenge, the exact threshold used to define response, and how assessments at different timepoints are handled. Without the observed denominators and estimates, the endpoint can be described but not quantitatively evaluated.

It also highlights a common challenge in follow-up studies: prior randomized assignment may remain useful for describing participants’ histories, but it is not equivalent to a new randomized comparison. Here, all participants received Viaskin Peanut during the open-label follow-up, while outcome categories reflected prior VIPES treatment. Differences in cumulative exposure between those categories further complicate a direct comparison.

Safety summaries require similar care. Counts of participants with serious and other adverse events convey what was recorded, but without a concurrent randomized group, they do not isolate treatment effects. The absence of a death count above zero does not resolve other questions about event timing, exposure, or causality.

The record also shows the value of reporting estimates with uncertainty and analysis details. A defined primary endpoint and a specified confidence-interval measure are not enough to assess findings if the percentages, interval limits, assessment counts, and missing-data methods are unavailable. Registry records can clarify study intent and structure, but their interpretive value depends on the completeness of posted results.

For biostatistical reading, the key distinction is between what a study intended to measure and what its record permits a reader to infer. The endpoint, treatment history, and selected safety counts are described; quantitative efficacy conclusions and formal comparative conclusions are not supported by the information reported.

14. 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.

This follow-up enrolled participants who had already participated in and completed VIPES. The registry record does not report how the decision to enter the follow-up related to participants’ health, response, or willingness to continue. In general, selection into a follow-up can limit how well results represent the original trial population or a broader population; this is a potential interpretive concern, not a documented bias in this study.

The study was open-label and had no newly randomized comparator. Participants and study personnel were not masked according to the record. For an endpoint determined by a double-blind, placebo-controlled food challenge, the challenge method itself is specified, but the registry record does not describe blinding or other procedures for the full follow-up. The lack of a concurrent randomized control limits causal interpretation of outcomes over time.

Primary endpoint results are described for participants who had the Month 12 and Month 24 challenges performed, while the full analysis set is defined as the intent-to-treat population consisting of all participants. The number assessed at either timepoint, missing-assessment reasons, and missing-data methods are not reported in the registry record. This prevents assessment of the extent to which reported results might represent the enrolled population.

Prior VIPES treatment groups also differed in cumulative active-treatment duration at each follow-up endpoint. The registry record does not report results that would allow those histories to be separated from other differences between participants. The group labels should therefore be understood as treatment history, not as randomized arms in this follow-up.

Finally, the record does not report primary response estimates, confidence-interval limits, a statistical analysis plan, multiplicity procedures, or a sample-size justification. These omissions restrict evaluation of effect magnitude, precision, and analysis choices. They do not establish that the study had a particular methodological flaw; they mark what cannot be verified from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Follow-up of the VIPES Study to Evaluate Efficacy and Safety of Viaskin Peanut in Adults and Children — NCT01955109.
• Registry record last updated 2022-06-30; status last verified 2022-06.
• Results first posted 2022-06-30.
• 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.

18. Record Summary

NCT01955109 is a completed Phase 2, open-label follow-up of VIPES participants with peanut allergy. The study enrolled 171 participants and evaluated Viaskin Peanut 250 mcg. Its primary outcome was the percentage of treatment responders at Month 12 and Month 24, using a food-challenge definition based on an eliciting dose of at least 1000 mg or an increase of at least 10-fold from VIPES baseline.

The follow-up was single-group, with no new randomized comparator. Primary outcome categories reflected prior VIPES treatment, and the record describes different cumulative active-treatment durations for those groups. It lists seven secondary outcomes and reports selected adverse-event counts, including zero deaths in each prior-treatment group.

The primary responder percentages and confidence intervals, the numbers assessed at each timepoint, the statistical analysis plan, and missing-data procedures are not reported in the registry record. The available information describes study intent and selected safety findings but does not permit a quantitative interpretation of the primary efficacy outcome.