Sublingual Cockroach Safety in Adults With Cockroach Allergy & Perennial Allergic Rhinitis With or Without Asthma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Sublingual Cockroach Safety in Adults With Cockroach Allergy & Perennial Allergic Rhinitis With or Without Asthma (NCT00434421), a na phase 1 study. The primary outcome is Proportion of Participants Who Discontinue Study.

2. Clinical Question

3. Trial Design

The registry describes a completed Phase 1 safety and pilot dosing study of glycerinated German cockroach allergenic extract given sublingually. It lists a single-group model, allocation as not applicable, and no masking. Enrollment is listed as 28. The study dates recorded are a start in 2007-02 and primary completion in 2009-08.

The population is described as having cockroach allergy and perennial allergic rhinitis, with or without asthma. The official title refers to pediatric and adult subjects, while the shorter title refers to adults; the record details do not provide enough eligibility information to reconcile that difference. The conditions listed are allergy and asthma.

The registry lists both glycerinated German cockroach allergenic extract and placebo as interventions. However, the named arm is the German Cockroach Allergen Dosing Group, described as receiving the extract. The endpoint description says that receiving the initial placebo dose counted as treatment initiation. That dose is part of the endpoint definition, not evidence of a concurrent placebo control group. Because the study is single-group and not randomized, it does not support a like-for-like comparison between extract and placebo.

The primary outcome concerns discontinuation for any reason after treatment initiation, over the interval from the initial placebo dose to the end of a 2-week treatment course, described as the maximum study dose. The registry lists one outcome measure and no analyses. It does not report a value for the primary endpoint, the dosing schedule, or the protocol’s analysis plan. Consequently, the design can be described, but the primary endpoint’s observed result and the details of how it was assessed cannot be established from 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: Safety Population: All study participants who were initiated onto the initial placebo study

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: All study participants who were initiated onto the initial placebo study treatment during the Preliminary Dosing Visit.

6. Primary Endpoint

The registry lists the primary outcome as Proportion of Participants Who Discontinue Study, measured over Initial placebo dose to end of 2-week treatment course (maximum study dose).

The primary endpoint is the proportion of participants who discontinued the study for any reason after treatment initiation. The record defines initiation as receiving the initial placebo dose and gives the observation interval as that dose through the end of a 2-week treatment course, described as the maximum study dose.

Discontinuation is a practical measure of whether participants remain in a study through its planned treatment period. In a safety and pilot dosing study, it can describe how often participation ends early, regardless of the reason. Because the endpoint includes discontinuation “for any reason,” it does not, by itself, distinguish discontinuation related to an adverse event from withdrawal for another reason, nor does it identify the reason for any individual’s discontinuation.

The registry names this endpoint but does not report its observed result. It also does not provide a breakdown of reasons for discontinuation or details of how missing endpoint information was handled. Therefore, no conclusion about the observed frequency of discontinuation can be drawn from the endpoint description alone.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group design mean?

A single-group study follows participants receiving the study intervention without a concurrent randomized control group. It can describe outcomes observed in the treated group, but it does not create a like-for-like comparison that separates treatment effects from other explanations for an outcome. Differences from a hypothetical untreated group cannot be estimated directly from this design. Here, the registry lists allocation as not applicable and masking as none, and names one German Cockroach Allergen Dosing Group.

The intervention list includes placebo as well as German cockroach allergenic extract. The endpoint description clarifies that the initial placebo dose defines the point of treatment initiation. This is not the same as a randomized placebo arm. The registry does not describe a control group, a random assignment process, or masking. Therefore, the listed placebo should not be interpreted as establishing a controlled comparison.

What does the primary endpoint capture?

The primary endpoint is the proportion of participants who discontinue study for any reason after initiation. A proportion is a way to express how common an event is within a defined group: the event is discontinuation, and the relevant group is the safety population defined as participants initiated onto the initial placebo study. The record specifies the timeframe from the initial placebo dose to the end of a 2-week treatment course, described as the maximum study dose.

An endpoint needs a clear event definition, population, and observation interval to be interpretable. The registry supplies these elements at a high level, but does not report the endpoint value. It also does not give a reason-specific breakdown or explain how a participant with incomplete follow-up was classified for this outcome. The observed discontinuation proportion and its precision therefore cannot be recovered from the registry entries.

How should counts and uncertainty be understood?

A count of affected participants is descriptive: it records how many people in the stated group had an event under the registry’s definition. A proportion relates that count to the people at risk, but no new proportion is calculated in this analysis. A confidence interval, when reported, gives a range of values compatible with the data and the method used to calculate it. It reflects statistical uncertainty, not a guarantee that the true value lies within the interval.

The registry lists safety counts but does not report confidence intervals or inferential tests for them. With no randomized comparator, even a precise description of observed events would not establish how the same participants would have fared without the intervention. General statistical interpretation also depends on whether event definitions, observation time, and follow-up are comparable across groups; this record does not present a second group for such a comparison.

For binary outcomes, such as whether an event occurred, the precision of an estimate depends on the amount of information available and on the event frequency. This is a general statistical point, not an additional result from this trial. It is particularly important not to confuse a zero observed count with proof that the underlying risk is zero. The registry records 0 participants affected by serious adverse events among 28 at risk; that count describes the observed record, not all possible future experience.

What are recalculated results and planning illustrations?

A recalculated result is a simple, unadjusted calculation from posted summary statistics. It can be useful as a check, but it does not replace a sponsor’s analysis when the results differ; in that circumstance, the sponsor’s own analysis takes precedence. The registry entries for this study do not report an analysis result for the primary endpoint, and no recalculated endpoint estimate is stated.

Sample-size calculations are planning illustrations rather than observed study outcomes. The assumptions associated with the planning illustration are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect described as a stated fraction of an observed effect. These assumptions do not describe the single-group design recorded for this study and should not be mistaken for its protocol or an analysis actually performed. The registry record does not report the protocol’s sample-size justification. A planning calculation is not observed power, and no such calculation can fill in an unreported endpoint result.

In general, over-dispersion occurs when outcome variability exceeds what a chosen statistical model assumes. Accounting for it can affect standard errors and uncertainty estimates. The registry entries do not report a model or a dispersion estimate for this study, so over-dispersion cannot be evaluated as a feature of its analysis.

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("German Cockroach Allergen Dosing Group")
n      <- c(28)
events <- c(2)
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  German Cockroach Allergen Dosing Group  28  2  7.1  0.9  23.5  2.0  22.6  2.2  22.8

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and no analyses. It does not report a statistical analysis plan, a hierarchy of outcomes, or whether any multiplicity adjustment was planned. Multiplicity arises when several outcomes or comparisons are tested; conducting many tests can increase the chance of finding an apparently notable result by chance. That general concern cannot be quantified for this study from the registry record, which does not describe a set of inferential tests.

The primary endpoint is defined for a safety population consisting of participants initiated onto the initial placebo study. The endpoint description says initiation occurs when a participant receives the initial placebo dose. The registry does not report how missing values were handled, whether any participants lacked endpoint follow-up, or whether all participants at risk contributed complete observation through the treatment period. It also does not report a participant flow accounting for the primary endpoint.

The safety counts list 28 participants at risk for serious adverse events and 28 at risk for other adverse events. These safety denominators do not substitute for a reported primary endpoint analysis. The record does not specify whether the safety population and endpoint analysis population were identical in practice, beyond the endpoint’s stated population definition.

Because no primary endpoint value or analysis details are reported, there is no basis to assess statistical adjustment, missing-data assumptions, or sensitivity analyses. These details are not reported in the registry record.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists 28 participants at risk for serious adverse events, with 0 affected, in the German Cockroach Allergen Dosing Group. It lists 28 at risk for other adverse events, with 15 affected. These are counts recorded for the study’s safety categories, not a randomized comparison of extract against placebo. The registry does not list serious adverse event terms, and the death count is not reported.

A zero observed count means no affected participants were recorded in that category in the registry entry. It does not demonstrate that the underlying possibility of a serious event is zero. Conversely, the count for other adverse events does not establish that the extract caused those events. The registry information presented does not specify event-level details, timing, severity, or causal assessment.

These safety counts should also be kept separate from the primary endpoint. The primary outcome is discontinuation for any reason, and its result is not reported. The adverse-event counts do not reveal how many participants discontinued, whether an adverse event prompted discontinuation, or why anyone left the study.

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

The record establishes the type and broad structure of the study: a completed Phase 1, single-group safety and pilot dosing study of sublingual glycerinated German cockroach allergenic extract. It identifies perennial allergic rhinitis with cockroach allergy, with or without asthma, as the clinical context. It also names discontinuation for any reason after treatment initiation as the primary endpoint and defines the treatment interval used for that outcome.

The posted safety counts indicate that 0 of 28 participants at risk were recorded as affected by serious adverse events, and 15 of 28 were recorded as affected by other adverse events. These counts describe the registry’s safety entries. They do not establish causation, comparative risk, or the experience that would have occurred under a control treatment. The registry also does not provide event terms for the serious category or a reported death count.

The primary endpoint’s observed result is not reported in the registry record. Accordingly, the entry does not show the proportion who discontinued, the reasons for discontinuation, or the precision of any estimate. It also does not provide an inferential analysis that would address uncertainty or compare outcomes across groups.

These findings should not be extended to claims about treatment efficacy. The registry’s single-group design does not provide a randomized comparator, and the listed placebo dose defines initiation rather than a placebo control arm. The available record supports a limited description of study design and recorded safety counts, but it does not answer whether the extract changes allergic symptoms or asthma outcomes. Those outcomes are not reported as results in the registry record.

14. Why This Trial Matters Statistically

This study illustrates why the design must be read alongside the numerical outcomes. A registry may list placebo among interventions, but a single-group model with allocation not applicable does not establish a randomized placebo comparison. In this record, the initial placebo dose has a specific role in defining treatment initiation for the discontinuation endpoint. Treating it as a control arm would misrepresent the study structure.

The endpoint also shows why a clear outcome definition is not enough to interpret a result: its observed value matters. The registry specifies discontinuation for any reason and gives the observation interval, yet does not report the result. Without that value, readers cannot describe the observed endpoint frequency or assess its statistical precision.

The safety entries provide another useful statistical distinction. A count of zero serious adverse events is an observation in a defined group, not evidence that an event is impossible. A count of other adverse events is likewise descriptive and does not establish that the intervention caused them. Neither count replaces a comparative analysis.

Finally, planning assumptions should not be confused with a study’s actual design or with observed power. The planning illustration’s assumptions refer to equal allocation between two arms, whereas this registry record describes a single-group study. Keeping planned calculations, observed outcomes, and analysis results distinct is essential for a sound reading of clinical-trial statistics.

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 registry record offers limited information for evaluating the primary endpoint. It names discontinuation for any reason after initiation and specifies a treatment interval, but does not report the observed result, reasons for discontinuation, or a precision estimate. It also does not provide participant flow or describe missing endpoint data.

The single-group design has no like-for-like randomized control comparison. The registry’s inclusion of placebo as an intervention does not resolve this limitation: the named arm receives allergenic extract, and the initial placebo dose defines initiation. Masking is listed as none. As a result, the record cannot support comparative conclusions about treatment effects.

The safety information is also limited in detail. The serious adverse event count is reported as 0 among 28 at risk, and the other adverse event count is 15 among 28 at risk, but event terms, timing, severity, and causal assessments are not reported in the registry record. The death count is not reported. The record does not supply an inferential safety analysis.

The shorter title refers to adults, while the official title refers to pediatric and adult subjects. Further eligibility details are not reported in the registry record. The dosing schedule and protocol’s statistical analysis plan are also not reported. These limitations restrict interpretation to the study description and registry-listed counts, rather than a full assessment of conduct or outcome analysis.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Sublingual Cockroach Safety in Adults With Cockroach Allergy & Perennial Allergic Rhinitis With or Without Asthma — NCT00434421.
• Registry record last updated 2015-06-11; status last verified 2015-06.
• Results first posted 2015-05-12.
• 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

NCT00434421 is listed as a completed Phase 1 study with a single-group model and no masking. It evaluated sublingual glycerinated German cockroach allergenic extract in the context of cockroach allergy and perennial allergic rhinitis, with or without asthma. Enrollment is listed as 28, with a start in 2007-02 and primary completion in 2009-08.

The primary endpoint was discontinuation for any reason after treatment initiation, defined by receipt of the initial placebo dose, through the end of a 2-week treatment course. The endpoint result is not reported in the registry record. Safety entries list 0 affected by serious adverse events among 28 at risk and 15 affected by other adverse events among 28 at risk. The record lists one outcome measure and no analyses.