This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Development of Cockroach Immunotherapy by the Inner-City Asthma Consortium (NCT01221285), a na phase 1 study. The primary outcome is Number of Reported Treatment-related Adverse Events (AEs).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01221285 |
| Phase | Phase 1 |
| Condition | Asthma, Perennial Allergic Rhinitis |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 11 |
| Arms in the primary outcome | n/a |
| Lead sponsor | National Institute of Allergy and Infectious Diseases (NIAID) |
| Results posted | Yes |
2. Clinical Question
Population
Cockroach-sensitive adults with a history of asthma, perennial allergic rhinitis, or both were the target population. The registry record reports enrollment of 11 participants. The primary outcome population is identified as intent-to-treat, while the safety record lists 10 at risk; the record does not explain the difference.
Intervention
Participants received German cockroach allergenic extract by subcutaneous injection. The regimen is described as weekly escalating doses, up to a maximum study dose of 0.6 mL of extract at a concentration of 1:20 wt/vol.
Comparator
There was no like-for-like control group. The study is recorded as single-group, with allocation listed as NA and masking as none. Its findings therefore describe outcomes within the treated group rather than a contrast between randomized treatment groups.
Primary question
The primary endpoint was the number of non-serious adverse events reported as possibly, probably, or definitely related to study participation from baseline through 6-months of treatment. The registry record does not report the numerical result. The study also lists changes in cockroach-specific antibodies and IgE fragment antibody binding activity as secondary outcomes, but their results are not reported in the registry record.
3. Trial Design
This was a Phase 1, biomarker-based pilot study of cockroach subcutaneous immunotherapy. The registry record identifies a single-group model, allocation as NA, and masking as none. These features mean the study was not a randomized comparison and does not provide a concurrent untreated or alternative-treatment group for a like-for-like contrast.
The intervention was German cockroach (Blattella germanica) allergenic extract, administered subcutaneously as weekly escalating doses. The arm description gives a maximum study dose of 0.6 mL at a concentration of 1:20 wt/vol. The registry describes the target population as cockroach-sensitive adults with a history of perennial allergic rhinitis, asthma, or both. The listed conditions are asthma and perennial allergic rhinitis.
The record reports enrollment of 11 and marks the study completed. It gives a start of 2010-09 and a primary completion of 2011-10. The primary outcome timeframe is baseline through 6-months of treatment. The primary analysis population is stated as intent-to-treat. The record does not report the protocol details needed to assess how the analysis population was defined in practice, how missing observations were handled, or whether outcome assessment procedures beyond the masking field were used.
The study's stated purpose was to examine safety, with biomarker changes also listed among the secondary outcomes. The registry record does not report a sample-size justification, interim analyses, or a detailed statistical analysis plan. The planning calculations associated with the posted results are illustrations rather than evidence that the trial was designed around those assumptions.
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
| Stage | Glycerinated German Cockroach Allergenic Extract |
|---|---|
| STARTED | 11 |
| COMPLETED | 10 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | Glycerinated German Cockroach Allergenic Extract |
|---|---|
| Withdrawal by Subject | 1 |
Analysis population for the primary outcome, as defined in the registry: Intent-to-treat
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.
| Characteristic | Unit | Glycerinated German Cockroach Allergenic Extract |
|---|---|---|
| Participants analysed | 10 | |
| Age, Continuous | years | 37.5 (24 to 52) |
| Sex: Female, Male: Female | Participants | 8 |
| Sex: Female, Male: Male | Participants | 2 |
| Region of Enrollment: United States | participants | 10 |
| Participants with Asthma | participants | 7 |
| Participants with Perennial Allergic Rhinitis | participants | 6 |
| Glycerinated German Cockroach Prick Skin Test Wheal Size | mm | 6.8 (3 to 9) |
| German Cockroach-Specific Serum Immunoglobulin E (IgE) Levels | kU/L | 3.8 (0.9 to 24.9) |
6. Primary Endpoint
The registry lists the primary outcome as Number of Reported Treatment-related Adverse Events (AEs), measured over Baseline through 6-months of treatment.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Events |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the number of non-serious adverse events reported as possibly related, probably related, or definitely related to study participation. Its timeframe is baseline through 6-months of treatment, and its population is identified as intent-to-treat. The endpoint is a count of events, not inherently a count of participants with at least one event. A participant could experience more than one event, so those quantities should not be treated as interchangeable.
In general, a safety count can describe the amount of reported event burden during a defined observation period. It is useful for characterizing what was observed during exposure, especially in a pilot study whose stated focus includes safety. However, a count alone does not show how events are distributed among participants, establish whether an event was caused by treatment, or compare risk with an alternative. The endpoint's relatedness categories reflect the registry's definition; they do not by themselves establish causation.
The registry record names the endpoint and its definition but does not report its numerical result. It also does not report a dispersion measure or confidence interval for this outcome. Consequently, the primary endpoint cannot be interpreted quantitatively from the registry record. The listed secondary outcomes concern changes in cockroach-specific serum IgE, IgG and IgG4, and IgE fragment antibody binding activity; their numerical results are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a primary safety endpoint, but does not give its event count. It therefore does not establish how many treatment-related non-serious events were observed during the stated timeframe. The outcome definition is informative about what was intended to be counted, but without the result there is no magnitude to interpret and no basis for describing the observed event burden as high, low, or otherwise.
The study is recorded as single-group, with no masking and no randomized comparator. Its design can describe outcomes recorded among participants receiving the extract, but it cannot separate treatment-associated changes from changes that might have occurred without treatment or under another intervention. In general, a comparison group helps distinguish treatment differences from background events and other influences. That distinction is particularly important when interpreting adverse events, because occurrence during treatment does not by itself establish that treatment caused an event.
The record reports enrollment of 11, while the adverse-event group lists 10 at risk for serious events and 10 at risk for other events. These figures should be read as the separate registry entries they are; the record does not explain the difference between the enrollment figure and the at-risk figures. It lists 2 participants affected for serious events and 10 affected for other events. The listed serious terms are bronchitis and localised infection, each shown as 10.0%. These figures are descriptive safety entries. They do not provide a randomized comparison, and the record does not establish whether any individual event was caused by the intervention.
Deaths are not reported in the registry record. A missing value should not be interpreted as a reported zero. The primary endpoint is explicitly about non-serious events judged possibly, probably, or definitely related; it should not be conflated with the serious-event figures, which are separately recorded.
The registry lists secondary antibody and binding-activity outcomes, but does not report their numerical results. Without those results, it is not possible to describe the direction or size of biomarker changes, or the precision of any such changes. Likewise, no reported estimate or uncertainty interval is available for the primary count. The statistical interpretation is therefore limited to the study structure, endpoint definition, and safety entries present in the registry record, rather than an estimate of treatment effect.
9. Statistical Methods Explained
The statistical methods that can be interpreted from the registry record are limited. The study is classified as a single-group Phase 1 pilot, and the primary endpoint is a count of treatment-related non-serious adverse events. The record does not report a detailed analysis plan, the numerical primary result, or an uncertainty measure. The explanations below describe general statistical principles and distinguish them from methods actually documented for this study.
What does a count endpoint represent?
In general, a count endpoint records how many events occurred over a defined observation period. It differs from a binary endpoint that records whether each participant experienced at least one event. When one participant can experience repeated events, a count includes those repeat occurrences, whereas a participant-level binary measure does not. For this trial, the stated endpoint is the number of events, and the description specifies non-serious events considered possibly, probably, or definitely related to study participation. The record does not report the numerical count or clarify whether repeated events were handled in any special way.
Counts may vary substantially between participants. In general, a count model may need to account for over-dispersion when variability is greater than a simple model assumes. Over-dispersion matters because a model that understates variability can produce uncertainty estimates that are too narrow. The registry record does not identify a count model, report a dispersion estimate, or provide enough numerical outcome information to assess the distribution of events. No particular model should therefore be attributed to this analysis.
How should a confidence interval be read?
In general, a confidence interval describes the uncertainty around an estimate under the assumptions of the analysis. A narrow interval indicates greater statistical precision than a wide interval, but neither width nor location alone establishes causality. For a count or rate, the interpretation depends on the estimate being reported and the method used to construct the interval. The registry record does not report a confidence interval for the primary endpoint. It is therefore not possible to assess its precision from the record.
A count can also be presented as a rate when an appropriate time-at-risk denominator is available. A rate and an event count answer different questions: the count describes observed events, while a rate relates events to exposure time. The registry record gives an endpoint timeframe but does not report an event rate or person-time analysis. No rate can be inferred from the listed count-related fields.
What can a single-group design establish?
In general, a single-group study can describe observations made in the enrolled group during the study. Without a concurrent comparison group, it cannot estimate a between-group treatment contrast. A before-and-after pattern, if reported, would also need careful interpretation because time trends, measurement variation, and other influences could contribute to change. Here, the registry record identifies a single-group model and does not report a randomized comparator. The primary result itself is not reported, so even a descriptive numerical account is unavailable.
The record identifies the primary outcome population as intent-to-treat. In general, an intent-to-treat analysis follows the population definition specified for the study and is often used to preserve the intended analysis groups in comparative trials. In a single-group study, the practical meaning still depends on the protocol's definition and the available observations. The registry record does not state how intent-to-treat membership was determined, whether all enrolled participants contributed to the endpoint, or how missing measurements were handled.
How do the planning calculations relate to the trial?
The sample-size calculations associated with the posted results are planning illustrations based on an observed effect, not the trial's own design. Their stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is expressed as a stated fraction of the observed effect. Those assumptions describe hypothetical planning scenarios. They do not change the recorded single-group design, and they do not show that the trial had a particular probability of detecting an effect.
In general, a planning sample size is conditional on assumptions about the effect, variability, allocation, statistical test, and desired power. If those assumptions differ from the eventual study design or data-generating process, the illustration may not describe the study's actual operating characteristics. The planning figures should not be called observed power. The registry record does not report a sample-size justification for the trial, and the planning calculations are not evidence of a prespecified sample-size target.
The stated planning approach uses a two-arm framework even though this trial is recorded as single-group. It is therefore best understood as a hypothetical planning comparison rather than a reconstruction of the trial's design. The record does not report the underlying values needed to evaluate those calculations in detail.
What is not documented?
The registry record does not report whether statistical models were used for the secondary biomarker outcomes, how repeated measurements were analyzed, or how uncertainty was quantified. It does not report interim analyses, a detailed statistical analysis plan, or a sample-size justification. The outcome list and analysis count alone do not establish which tests were conducted, whether analyses were prespecified, or whether adjustment for multiple testing was applied. Those methodological details should be treated as not reported in the registry record rather than inferred from the study's pilot or biomarker-based description.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists 6 outcome measures and 4 analyses. The secondary outcomes include changes over time in German cockroach-specific serum IgE, IgG, and IgG4, as well as change in IgE fragment antibody binding activity at 10 Micrograms/mL cockroach allergen extract. The record does not report numerical results for these outcomes. The primary endpoint is a separate count of treatment-related non-serious adverse events.
When a study evaluates several outcomes or conducts several analyses, there may be more opportunities to find an apparently unusual result by chance. In general, multiplicity procedures can control the overall false-positive rate or otherwise clarify how results should be interpreted. The registry record does not report whether any adjustment was used, which outcomes were treated as primary or secondary in the analysis plan beyond the listed primary endpoint, or how the 4 analyses relate to the 6 outcome measures. Their counts alone do not establish a multiplicity strategy.
The primary endpoint population is identified as intent-to-treat. The registry record does not report how that population was operationalized, whether outcome data were available for everyone in it, or how missing primary endpoint data were handled. Missing data methods for the biomarker outcomes are also not reported in the registry record. No assumption about complete follow-up, imputation, exclusion, or other missing-data handling can be made from the listed information.
The adverse-event record separately lists 10 at risk for serious events and 10 at risk for other events, while enrollment is 11. The record does not explain the relationship among these entries or how participants with incomplete safety information were handled. These limitations constrain assessment of the analysis populations and completeness of follow-up.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Experimental: German Cockroach Allergenic Extract | 2 | 10 | 20.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Experimental: German Cockroach Allergenic Extract | 10 of 10 |
Most frequent serious adverse event terms
| Event term | Organ system | Experimental: German Cockroach Allergenic Extract |
|---|---|---|
| Bronchitis | Infections and infestations | 1 of 10 |
| Localised infection | Infections and infestations | 1 of 10 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Experimental: German Cockroach Allergenic Extract |
|---|---|---|
| Injection site pruritus | General disorders | 9 of 10 |
| Injection site swelling | General disorders | 9 of 10 |
| Injection site erythema | General disorders | 6 of 10 |
| Throat irritation | Respiratory, thoracic and mediastinal disorders | 3 of 10 |
| Pruritus | Skin and subcutaneous tissue disorders | 3 of 10 |
| Ear pruritus | Ear and labyrinth disorders | 2 of 10 |
| Injection site erosion | General disorders | 2 of 10 |
| Injection site pain | General disorders | 2 of 10 |
| Cough | Respiratory, thoracic and mediastinal disorders | 2 of 10 |
| Rhinorrhoea | Respiratory, thoracic and mediastinal disorders | 2 of 10 |
Serious events with the highest arm-level rate: bronchitis (10.0%), localised infection (10.0%).
The registry record lists 10 at risk for serious adverse events and 2 participants affected. For other adverse events, it lists 10 at risk and 10 affected. The two serious terms listed are bronchitis and localised infection, each shown as 10.0%. These are descriptive entries in the safety record; the percentages are reported as given and should not be read as evidence of causation.
The serious-event figures are distinct from the primary endpoint, which counts non-serious events judged possibly, probably, or definitely related to study participation. The serious-event listing does not state that these events were considered related to treatment. Nor does the record establish that the listed terms account for every event or specify how often an event recurred within a participant.
The registry record reports enrollment of 11 but gives 10 at risk in each safety category. It does not explain that difference, so the safety denominators should not be silently replaced with the enrollment figure. Deaths are not reported in the registry record; the unreported value should not be interpreted as a zero. Because the study has no like-for-like control group, these entries cannot be used to estimate a comparative safety difference.
12. What the Result Does, and Does Not, Mean
The record supports a limited description of the study's design and its recorded safety entries. It describes a completed, single-group pilot of German cockroach allergenic extract in cockroach-sensitive adults with asthma and/or perennial allergic rhinitis. The intervention was given as weekly escalating subcutaneous doses, with a stated maximum study dose of 0.6 mL at 1:20 wt/vol. The registry lists 11 enrolled participants and separately records safety figures for 10 at risk.
The primary outcome was defined as the number of non-serious adverse events reported as possibly, probably, or definitely related to study participation from baseline through 6-months of treatment. Its numerical result is not reported in the registry record. The listed serious-event entries identify 2 participants affected among 10 at risk, while the entries for other events identify 10 affected among 10 at risk. The serious-event terms and percentages are descriptive registry information; they do not on their own establish a causal relationship with the intervention.
The record does not support a comparison of treatment with no treatment or with another treatment because it identifies a single-group design and no randomized comparator. In general, observations during treatment can be affected by background events and other factors, so timing alone cannot establish that treatment caused an outcome. The absence of a comparison also means the record cannot estimate a relative treatment effect.
The secondary biomarker outcomes are listed, but their results are not reported in the registry record. Their direction, magnitude, and precision therefore cannot be described. The record also does not report a numerical primary endpoint result, a confidence interval, or the missing-data and multiplicity methods. These omissions limit conclusions about both the safety endpoint and the biomarker findings.
Accordingly, the study description and safety entries can be read as a record of what was planned and listed, not as sufficient evidence for a definitive estimate of benefit, harm, or comparative effect. No treatment recommendation follows from these registry entries.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of the distinction between describing outcomes and estimating comparative effects. Its single-group structure can document what was observed among participants who received German cockroach allergenic extract, but it does not provide a like-for-like control group. A treatment contrast cannot be inferred from a treated group alone.
The primary endpoint also illustrates why an outcome definition and an outcome result are both needed. The registry record carefully identifies the event type, relatedness categories, timeframe, and analysis population. But it does not report the count itself. Without that numerical result, readers cannot assess the observed burden or its precision, even though the endpoint definition is available.
The separate safety entries help demonstrate the importance of keeping endpoints and denominators distinct. The primary endpoint concerns non-serious treatment-related events, whereas the safety record separately lists serious and other events. Enrollment is 11, while the safety entries list 10 at risk. Because the record does not explain the difference, readers should retain the recorded denominators rather than assume they are interchangeable.
The study also lists biomarker outcomes, but does not report their numerical findings or analysis details. In general, several outcomes can raise questions about multiplicity and selective interpretation. Here, the registry does not state whether any adjustment was used, so no such method can be credited to the analysis. The record also does not report missing-data procedures or a sample-size justification.
Finally, planning calculations based on an observed effect are not the same as a trial's design rationale or observed power. The stated planning assumptions use equal allocation between two arms, while the trial itself is recorded as single-group. Recognizing that distinction helps prevent hypothetical planning scenarios from being mistaken for evidence about this study's actual design or results.
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.
The principal limitation for interpreting the posted results is that the registry record does not report the numerical primary endpoint result. Although the outcome is defined as a count of non-serious adverse events considered possibly, probably, or definitely related, there is no reported count or uncertainty measure with which to evaluate it. The secondary biomarker outcomes are also listed without numerical results.
The study is recorded as single-group and unmasked, with allocation listed as NA. As a result, the record does not offer a randomized, like-for-like comparator. Descriptive outcomes cannot establish what would have happened under another treatment or without the intervention, and event occurrence during treatment does not by itself demonstrate causation.
The registry reports enrollment of 11 but lists 10 at risk for serious events and 10 at risk for other events. It does not explain the distinction. The serious-event record lists 2 participants affected, while the other-event record lists 10 affected; deaths are not reported in the registry record. These entries do not reveal how incomplete safety follow-up was addressed, whether events recurred, or how relatedness was assessed for the separately listed serious terms.
Other trial-specific details are also not reported in the registry record: a sample-size justification, interim analyses, a detailed statistical analysis plan, missing-data methods, and the approach to multiplicity. The record lists 6 outcome measures and 4 analyses but does not describe how they correspond or whether adjustments were made. These gaps prevent assessment of analysis choices and precision beyond the information explicitly recorded.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Development of Cockroach Immunotherapy by the Inner-City Asthma Consortium — NCT01221285.
- Registry record last updated 2014-06-11; status last verified 2014-06.
- Results first posted 2014-05-23.
- 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.
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18. Record Summary
The registry record describes NCT01221285, a completed Phase 1, biomarker-based pilot study of German cockroach subcutaneous immunotherapy in cockroach-sensitive adults with asthma and/or perennial allergic rhinitis. The study is recorded as single-group, with no masking and allocation listed as NA. Enrollment is 11. The intervention involved weekly escalating subcutaneous doses, up to a maximum study dose of 0.6 mL at a concentration of 1:20 wt/vol.
The primary endpoint was the number of non-serious adverse events considered possibly, probably, or definitely related to study participation, from baseline through 6-months of treatment, in an intent-to-treat population. Its numerical result is not reported in the registry record. The safety entries list 10 at risk and 2 affected for serious events, and 10 at risk and 10 affected for other events. Bronchitis and localised infection are each listed at 10.0%; deaths are not reported in the registry record.
Secondary outcomes concern cockroach-specific antibody changes and IgE fragment antibody binding activity, but their results are not reported. The single-group design does not provide a like-for-like control comparison.