Effect of Omalizumab on Expression of IgE Receptors in Adults With Severe, Inadequately Controlled Allergic Asthma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effect of Omalizumab on Expression of IgE Receptors in Adults With Severe, Inadequately Controlled Allergic Asthma (NCT00454051), a randomized phase 4 study. The primary outcome is Change (%) From Baseline in FcεRI (High-affinity IgE Receptor) Expression on Blood Basophils and Dendritic Cells After 16 Weeks of Treatment With Omalizumab as Compared With Placebo.

2. Clinical Question

3. Trial Design

This was a randomized, quadruple-masked, parallel-group phase 4 study comparing omalizumab with placebo. The registry record identifies asthma as the condition and gives a total enrollment of 31. It does not report the randomization sequence, allocation concealment method, or the exact number assigned to each group for the primary analysis. The description quadruple-masked is recorded, but the record does not specify which groups of people were masked.

Omalizumab and placebo were injected subcutaneously every 2 weeks or every 4 weeks during 16 weeks of treatment. For omalizumab, dose and dosing interval depended on body weight and pretreatment serum IgE level. The placebo schedule is described as matching those intervals. Exact dose levels and rules for selecting the interval are not reported in the registry record.

The study start is listed as 2006-12, and primary completion as 2008-03. The status is completed. These dates describe the registry record; they do not establish how long individual participants were followed beyond the stated treatment period.

The principal endpoint concerned percent change from baseline to Week 16 in FcεRI expression on blood basophils and dendritic cells. Secondary outcomes included changes in FcεRI-positive cell percentages and fluorescence intensity at multiple post-baseline assessments, as well as weekly asthma symptoms, rescue medication use, nighttime awakenings, daily-activity impairment, school or work absence, and hospitalizations. The registry lists 13 outcome measures, but does not report the results for these outcomes in the record used for this account.

The registry record does not report a sample-size justification or a detailed statistical analysis plan. Randomization and masking describe design features; by themselves, they do not establish that groups were balanced on every characteristic or explain how outcome data were analyzed.

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: The Intent-to-treat (ITT) population analyzable for FcεRI expression was a subset of the ITT population and included the 27 participants with accurate measurements before and after 16 weeks of treatment.

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.

6. Primary Endpoint

The registry lists the primary outcome as Change (%) From Baseline in FcεRI (High-affinity IgE Receptor) Expression on Blood Basophils and Dendritic Cells After 16 Weeks of Treatment With Omalizumab as Compared With Placebo, measured over Baseline and Week 16.

The primary endpoint is percent change from baseline in FcεRI expression on blood basophils and dendritic cells at Week 16. FcεRI is described in the record as a high-affinity IgE receptor. Blood was collected at baseline and Week 16; cells expressing the receptor were counted, and the percentage was calculated. Fluorescence labeling made FcεRI visible, with greater fluorescence intensity corresponding to greater receptor expression.

The endpoint expresses the change relative to the baseline value. In general, a percent change can make changes interpretable in relation to each participant’s starting measurement, but it can also be sensitive to baseline values and to measurement variability. The record defines the endpoint as the percent difference between the baseline value, before the first study-drug administration, and the value at the end of the study, expressed as a percent of baseline.

Measuring this receptor provides a biological outcome relevant to the study’s stated aim of examining IgE-receptor expression during treatment. It is not, by itself, a direct measure of how participants feel or function. The registry lists other outcomes addressing asthma symptoms and daily impacts, but the primary endpoint description does not establish that a biomarker change corresponds to a change in those outcomes.

The analyzed population for FcεRI expression comprised 27 participants with accurate measurements both before and after 16 weeks of treatment, described as a subset of the intent-to-treat population. The registry record does not report the observed endpoint values, variability, or comparison between treatment groups.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The design uses random assignment to compare omalizumab with placebo. In general, randomization aims to make treatment groups comparable, on average, with respect to both measured and unmeasured characteristics at the time of assignment. It does not guarantee balance in a small study, and the record does not provide baseline characteristics or details of the assignment process. The parallel-group design means that participants were assigned to a treatment group rather than crossing between treatments, as described by the registry.

What does the mean represent?

The primary outcome is continuous and is summarized using a mean. A mean combines the individual participants’ endpoint values into an average. For this trial, the endpoint is percent change in FcεRI expression from baseline to Week 16. The mean can describe the average change in an arm, but it does not show whether individual responses were similar or widely dispersed. The registry identifies standard deviation as the measure of dispersion; a larger standard deviation generally indicates more spread among individual observations.

Arm means and a treatment contrast answer different questions. An arm mean describes observed change within that group. A between-group contrast compares the average changes across the randomized groups and is the relevant summary for the comparative question. A within-group change alone does not establish a treatment difference, because changes may also occur under placebo or reflect time, measurement variation, or other influences. No means, standard deviations, or contrast are reported for the primary outcome in the registry record.

How should uncertainty be read?

In general, a confidence interval expresses uncertainty around an estimated quantity under the analysis assumptions. A narrow interval indicates greater precision than a wide interval, though precision does not determine whether a difference matters clinically. A p-value, when reported, addresses how compatible the observed data are with a specified null hypothesis under the statistical model. It is not the probability that the null hypothesis is true, nor does it measure clinical importance. Neither a confidence interval nor a p-value for the primary comparison is reported in the registry record.

Standard deviation and standard error should not be confused. Standard deviation describes variation in participant measurements. Standard error describes uncertainty in an estimated mean or contrast and depends on the data and analysis. The registry specifies standard deviation for the endpoint’s dispersion but does not provide uncertainty estimates or enough summary statistics to reconstruct them. No recalculated comparison can be made from the recorded endpoint information.

Why does the endpoint use percent change?

Percent change relates the difference between the baseline and follow-up measurements to the baseline value. This can be useful when the starting level varies across participants, because the change is expressed relative to each starting measurement. It can also make interpretation more sensitive to the baseline value: the same absolute change can correspond to different percent changes at different starting levels. Measurement error at baseline can affect the calculated change as well. These are general properties of percent-change outcomes, not findings about this trial’s participants.

For a measurement with a baseline value close to zero, percent change can be unstable. The registry record does not report baseline values or indicate whether this issue occurred. It also does not provide the exact statistical model used to analyze the outcome. It would therefore be inappropriate to assume that the analysis used a particular adjustment, transformation, or covariance structure.

What do the planning illustrations mean?

The stated planning assumptions describe illustrations based on an observed effect, using a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation. The effect to detect is expressed as a stated fraction of the observed effect. Such illustrations concern how many participants per arm might be required under those assumptions; they are not evidence about the trial’s actual power and are not a record of the original design justification. The registry record does not report a sample-size justification for the trial itself. The observed effect and the fractions used for the illustrations are not stated in the available record, so no planning quantity can be interpreted.

Power is a property of a specified design and assumed effect, variability, and analysis procedure. It is not a post hoc measure of whether a completed study produced a reliable answer. Planning calculations do not repair missing outcome results, and they do not show whether the study detected a difference. The record does not report the assumptions used by the original investigators to plan enrollment.

What does masking add?

Masking is intended to limit influences on treatment delivery, participant reporting, measurement, or analysis that could arise from knowing the assigned group. The registry classifies the study as quadruple-masked, but does not identify the roles masked or explain how masking was maintained. The classification alone does not establish whether masking remained intact throughout the study.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint alongside multiple secondary outcomes. The primary measure concerns FcεRI expression at Week 16, while other listed measures include receptor expression at additional assessment times, fluorescence intensity, and several asthma-related experiences. When multiple outcomes or time points are tested, the chance of finding at least one nominally unusual result can increase. In general, analysis plans may address this through a prespecified hierarchy, adjustment, or a clearly designated primary comparison. The registry record does not report a multiplicity strategy, so it is not possible to determine whether or how the analyses accounted for multiple comparisons.

The record notes that the primary outcome has several categories or time points and was not reduced to one comparison. It therefore does not present a single primary contrast for interpretation in this account. The registry record does not identify which specific category or time-point comparison would be treated as primary if the endpoint were separated into multiple tests.

For FcεRI expression, the analyzable population consisted of 27 participants with accurate measurements before and after 16 weeks, described as a subset of the intent-to-treat population. The registry does not report the number with missing or inaccurate measurements in each arm, the reasons for missing measurements, or whether any values were imputed. It also does not describe sensitivity analyses for missing data. These details matter because an analysis based only on participants with complete measurements can be affected if availability of measurements is related to treatment or outcome.

The phrase intent-to-treat appears in the description of the analyzable subset; it does not mean that all enrolled or randomized participants necessarily contributed measurements to this endpoint. The record does not specify the full randomized population or the analysis approach used for participants without accurate paired measurements. It lists no analysis records. These reporting gaps limit assessment of multiplicity, missing-data assumptions, and alignment between the planned and reported analyses.

11. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: asthma (9.1%).

The registry reports serious adverse event counts with group-specific numbers at risk: 0 among 20 participants at risk in the omalizumab group and 1 among 11 at risk in the placebo group. For other adverse events, it reports 13 among 20 at risk in the omalizumab group and 7 among 11 at risk in the placebo group. These are counts, not estimates of comparative risk, and they should be read with their stated denominators. No percentages or adjusted comparisons are reported for these group summaries.

The record lists Asthma at 9.1% among the top serious adverse event terms. It does not give enough detail in this entry to assign that term and percentage to a particular group or to establish how the term relates to the group-level serious-event counts. The registry record does not report death counts; the death entries are not populated. That should not be interpreted as evidence that no deaths occurred.

Adverse-event summaries are descriptive. Differences in raw counts do not, on their own, establish a treatment-related effect. Interpretation also depends on definitions, observation time, event ascertainment, and the number of participants contributing safety information. The registry entry does not provide those details beyond the counts and at-risk numbers stated above. These summaries should not be treated as a complete characterization of safety or as a substitute for clinical judgment.

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

This trial was designed to compare a biological measure between omalizumab and placebo in adults with severe, inadequately controlled allergic asthma. Its primary measure was percent change in FcεRI expression on blood basophils and dendritic cells from baseline to Week 16. The registry record supplies a description of the measurement and identifies the population with accurate paired measurements, but it does not state the outcome results.

As a result, the record does not establish whether the average biomarker change differed between treatment groups, how large any difference was, or how precisely it was estimated. It also does not support a conclusion about whether any biomarker change corresponded to a change in symptoms, rescue medication use, nighttime awakenings, daily activities, absence from school or work, or hospitalizations. Those outcomes are listed, but their results are not reported in the registry record.

Even a reported difference in this biomarker would need to be interpreted according to its size, uncertainty, and relationship to outcomes that matter to participants. A statistically detectable difference is not automatically important in practice, and a non-significant result would not by itself prove that the groups were equivalent. Equivalence or non-inferiority requires an appropriate design and prespecified criteria; these are not described in the registry record.

The study’s randomized and masked design is relevant to how a comparison could be interpreted, but design labels do not replace reported results. The available safety counts are descriptive and do not establish causation. The appropriate conclusion is limited: the registry documents the trial’s question, treatment schedules, endpoint definition, and selected safety counts, while leaving the primary comparative result and key analysis details unreported.

13. Why This Trial Matters Statistically

This study is statistically interesting because it connects a laboratory-based outcome with a clinical condition and includes both a biological primary endpoint and patient-experience outcomes. The primary measure concerns FcεRI expression on two cell types, while secondary outcomes cover symptoms, rescue medication, sleep interruption, activity, absence from school or work, and hospitalization. These outcomes capture different dimensions and should not be treated as interchangeable.

The record also illustrates why analysis population definitions matter. Enrollment is reported as 31, while the primary endpoint analysis is described for a subset of 27 participants with accurate measurements before and after treatment. That distinction affects how readers understand the population represented by an endpoint estimate. Without group-specific analysis counts, missing-data details, and results, the relation between the randomized comparison and the measured endpoint remains difficult to assess.

A further statistical issue is the number of outcomes and assessment times. Multiple comparisons can complicate interpretation unless their role and handling are prespecified and reported. The registry record does not describe such a plan. The primary endpoint itself is described across cell types, and other outcomes include repeated assessments, but no single comparative result is reported.

Finally, the entry demonstrates the difference between a trial record and a full statistical report. A registry can identify design features and endpoint definitions without providing the estimates and uncertainty needed to assess a treatment contrast. In this case, the design and measurement descriptions are useful, but the absence of primary outcome results limits what can be concluded statistically.

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 most important limitation of interpretation is that the registry record does not report the primary endpoint results. There are no arm-specific means or standard deviations, no between-group estimate, and no reported interval or p-value. Without these, neither the direction nor the precision of the biomarker comparison can be assessed.

The analyzed endpoint population is described as 27 participants with accurate baseline and Week 16 measurements, but the record does not give the number in each treatment group or explain why other participants were not included in that analysis. It also does not report whether missing or inaccurate measurements were related to treatment, baseline characteristics, or outcomes. This prevents assessment of possible selection effects and missing-data assumptions.

The measurement description does not include detailed laboratory procedures, reproducibility information, or the exact statistical model. The registry record does not report whether baseline values were adjusted for, how the outcomes for basophils and dendritic cells were combined or separately assessed, or how the multiple time points and outcomes were handled statistically. These details should not be inferred from the endpoint label.

The record states that treatment dose and interval were determined by body weight and pretreatment serum IgE level, but it does not give dose levels or participant-level treatment information. It describes quadruple masking without specifying the masked roles. It also does not provide baseline clinical characteristics, adherence information, or a detailed account of follow-up beyond the stated treatment period.

Although selected adverse-event counts are reported, deaths are not populated and the record does not provide enough detail to interpret the listed serious-event term by treatment group. The registry entry also does not report the original sample-size justification or detailed analysis plan. These gaps constrain both efficacy and safety interpretation; they do not establish that an unreported event or analysis did or did not occur.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Effect of Omalizumab on Expression of IgE Receptors in Adults With Severe, Inadequately Controlled Allergic Asthma — NCT00454051.
• Registry record last updated 2011-08-08; status last verified 2011-08.
• Results first posted 2011-08-01.
• 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

The registry describes a completed randomized, quadruple-masked, parallel-group phase 4 study of omalizumab versus placebo in adults with severe, inadequately controlled allergic asthma. Enrollment was 31. Treatment was given by subcutaneous injection every 2 weeks or every 4 weeks for 16 weeks, with omalizumab dosing based on body weight and pretreatment serum IgE level.

The primary endpoint was percent change from baseline in FcεRI expression on blood basophils and dendritic cells at Week 16. The endpoint population included 27 participants with accurate measurements at baseline and Week 16. The registry record does not report the primary comparative results, the statistical analysis plan, or details of missing outcome data. It reports selected serious and other adverse-event counts by group, but does not populate death counts.