Efficacy and Safety of Omalizumab in Children (6 - < 12 Years) With Moderate-severe, Inadequately Controlled Allergic Asthma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy and Safety of Omalizumab in Children (6 - < 12 Years) With Moderate-severe, Inadequately Controlled Allergic Asthma (NCT00079937), a randomized phase 3 study. The primary outcome is Rate of Clinically Significant Asthma Exacerbations Per Patient in the 24-week Fixed-dose Steroid Treatment Period.

2. Clinical Question

The trial asked whether omalizumab, compared with placebo, was associated with a different rate of clinically significant asthma exacerbations during a fixed-dose steroid treatment period in children with moderate-to-severe, inadequately controlled allergic asthma. The registered age range was 6 to < 12 years. The primary outcome covered the period from baseline to the end of the 24-week fixed-dose steroid phase.

The registry describes the trial as randomized, quadruple-masked, parallel-group, and placebo-controlled. It also lists fluticasone among the interventions, but further details about its role are not reported in the registry record. The primary outcome concerns exacerbations requiring specified escalation of asthma treatment, rather than all symptom changes or all asthma events.

3. Trial Design

This was a Phase 3, randomized, quadruple-masked, parallel-group, placebo-controlled study sponsored by Novartis Pharmaceuticals. The registry lists 628 participants enrolled and gives the status as completed. The study began in 2004-04, with primary completion in 2008-03. Its official title describes a 1-year evaluation of efficacy, safety, pharmacokinetics, and pharmacodynamics in children with allergic asthma.

Participants were assigned to omalizumab or placebo. The registry describes both as subcutaneous injections given every 2 or 4 weeks over 52 weeks. Omalizumab dosing was based on body weight and total serum IgE measured at screening. The first 24 weeks were described as a fixed steroid phase, and the primary endpoint was assessed over that phase. The registry also lists fluticasone as an intervention, but the available arm descriptions do not establish the details of its use.

Although enrollment was 628, the primary endpoint reports an analysis population of 384 participants in the omalizumab arm and 192 in the placebo arm. The stated modified intent-to-treat definition excluded randomized participants from 2 sites because of Good Clinical Practice non-compliance; those participants were replaced by participants at other sites. The registry does not describe the reasons for the difference between total enrollment and the numbers in the primary endpoint arms beyond that exclusion and replacement information.

The study design supports a comparison between assigned groups, but interpretation still depends on how outcomes were defined, analyzed, and reported. The primary outcome used a model adjusted for time at risk and listed covariates. Details such as the original sample-size justification and any interim analyses are not reported in 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: Modified intent-to-treat population: All patients who were randomized, excluding patients from 2 sites due to Good Clinical Practice non-compliance. Excluded patients were replaced with patients at other sites to maintain statistical power.

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 Rate of Clinically Significant Asthma Exacerbations Per Patient in the 24-week Fixed-dose Steroid Treatment Period, measured over Baseline to end of the fixed-dose steroid treatment period (Week 24).

The primary endpoint was the rate of clinically significant asthma exacerbations per patient during the 24-week fixed-dose steroid treatment period. A clinically significant exacerbation was defined as worsening asthma symptoms, judged clinically by the investigator, that required doubling the baseline inhaled corticosteroid dose and/or treatment with systemic rescue corticosteroids for at least 3 days. The result is an event rate over a specified period, not simply the proportion of participants who had at least one exacerbation.

Rates are useful when participants may contribute different amounts of observation time or may experience more than one event. The registry says the analysis accounted for each participant’s time at risk, measured in person-days during the fixed-dose steroid period. It used a Poisson model adjusted for time at risk and for country, exacerbation history, and dose schedule.

The primary period is important to the interpretation: it ends at Week 24 and is not the full 52-week treatment period. The registry also reports a separate exacerbation-rate outcome over the 52-week treatment period, but that is a secondary outcome. The primary endpoint therefore answers a defined question about clinically significant exacerbations during the fixed-dose steroid phase, not every aspect of asthma control or the entire year of treatment.

In general, a rate summarizes the frequency of events relative to exposure time. A confidence interval expresses uncertainty around an estimate under the model and analysis assumptions. Neither measure by itself describes the experience of every participant, and the rate should be read alongside the event definition and the stated analysis population.

7. Results Posted in the Registry

• Omalizumab: 0.45 versus 0.64 (Exacerbations per patient per 24-weeks) on control; rate ratio 0.70 (95% CI 0.50–0.99, derived from the posted confidence limits); p ≈ 0.041.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Change in Mean Nocturnal Asthma Symptom Score From Baseline to the End (Last 4 Weeks) of the 24-week Fixed-dose Steroid Treatment Period

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Omalizumab: mean -0.63 versus -0.50 on control; difference -0.13 (95% CI -0.25 to -0.01), standardized effect d = -0.18; z-test p = 0.040.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Omalizumab than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Rate of Clinically Significant Asthma Exacerbations Per Patient in the 52-week Treatment Period

• Endpoint type: Event rate: events per unit of follow-up, compared as a rate ratio.
• Test: Poisson rate ratio, with the standard error taken from the posted confidence limits.
• Result:
  • Omalizumab: 0.78 versus 1.36 (Exacerbations per patient per year) on control; rate ratio 0.57 (95% CI 0.40–0.82, derived from the posted confidence limits); p ≈ 0.003.
• Interpretation:
  • The 95% confidence interval excludes no difference (a ratio of 1), so the event rate is statistically lower for Omalizumab than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Change in Mean Daily Number of Puffs of Asthma Rescue Medication From Baseline to the End (Last 4 Weeks) of the 24-week Fixed-dose Steroid Treatment Period

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Omalizumab: mean -1.30 versus -1.00 on control; difference -0.30 (95% CI -0.75 to 0.15), standardized effect d = -0.11; z-test p = 0.196.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Omalizumab and the control. The interval gives the range of effects that remain compatible with the data.

The posted secondary outcomes broaden the view beyond the primary 24-week exacerbation rate. They include a nocturnal symptom score and rescue-medication use during the fixed-dose steroid phase, a separate exacerbation-rate outcome over the full 52-week treatment period, and a pediatric asthma quality-of-life questionnaire outcome. Together, these outcomes address symptoms, medication use, events over a longer timeframe, and reported quality of life.

The available numerical results do not point uniformly in one direction with equal precision. The nocturnal symptom-score comparison is in the same general direction as the primary result, while the full-year exacerbation-rate comparison also has a rate-ratio interval on the side favoring a lower estimated rate for omalizumab. The rescue-medication-puff comparison is less precise relative to its no-difference reference, with its interval including zero. Results for the quality-of-life questionnaire are not reported in the registry record. These observations are not a substitute for the primary endpoint and do not establish a single overall effect across distinct measures.

Each secondary outcome uses a different scale, timeframe, or clinical construct. A change in a symptom score is not equivalent to an event rate, and a longer observation period is not interchangeable with the primary fixed-dose steroid period. The secondary results therefore add context but should not be combined informally into one summary conclusion.

Unadjusted secondary comparisons carry less weight because multiple outcomes create multiple opportunities for apparently notable findings. The registry does not report a multiplicity adjustment or a hierarchy for interpreting the secondary analyses. Without those details, individual unadjusted p-values are best viewed as exploratory evidence rather than as stand-alone confirmation. The registry also does not report results for every listed secondary outcome, limiting assessment of the full pattern.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Change in Mean Nocturnal Asthma Symptom Score From Baseline to the End (Last 4 Weeks) of the 24-week Fixed-dose Steroid Treatment Period
• Rate of Clinically Significant Asthma Exacerbations Per Patient in the 52-week Treatment Period
• Change in Mean Daily Number of Puffs of Asthma Rescue Medication From Baseline to the End (Last 4 Weeks) of the 24-week Fixed-dose Steroid Treatment Period
• Change in Pediatric Asthma Quality of Life Questionnaire (Standardized) [PAQLQ(S)] Scores From Baseline to the End of the 24-week Fixed-dose Steroid Treatment Period (Week 24)

9. Statistical Interpretation

10. Statistical Methods Explained

What does the primary rate estimate represent?

For the primary endpoint, the outcome is a count of clinically significant exacerbations considered in relation to participants’ time at risk. A rate differs from a simple percentage: a participant can contribute time without an event, and a participant may experience more than one event. The registry reports the result as exacerbations per patient per 24 weeks. In general, expressing events relative to exposure time helps account for differences in how long participants are observed and at risk.

The registry says the rate was estimated using a Poisson model adjusted for time at risk and the listed covariates: country, exacerbation history, and dose schedule. A Poisson model is a statistical approach often used for event counts. In general, it relates counts to exposure and can incorporate explanatory variables. Its assumptions matter: if event counts vary more than the model allows, uncertainty estimates can be too small unless that extra variation is addressed. Whether such checks or alternative models were used is not reported in the registry record.

How should the rate ratio be read?

A rate ratio compares the estimated event rate in one group with the rate in the comparison group. A value of 1 represents equal estimated rates; values below 1 indicate a lower estimated rate in the named treatment group, while values above 1 indicate a higher estimated rate. These are general interpretations of the measure. For the primary outcome, the posted rate ratio estimate and its confidence interval are below 1. The rate ratio is a relative comparison and should be read with the group-specific rates, which show the outcome on its original scale.

The registry also posts an unadjusted p-value for the comparison. A p-value measures how compatible the observed data are with a specified null model, under the analysis assumptions; it is not the probability that the null hypothesis is true. The posted p-value is explicitly unadjusted, while the primary rate estimate is described as derived from a covariate-adjusted Poisson model. The registry does not explain the precise relationship between the posted p-value and the adjusted model estimate. The value should therefore be identified as unadjusted rather than presented as a multiplicity-adjusted or otherwise model-adjusted significance test.

What do the continuous secondary measures mean?

The nocturnal symptom score and daily rescue-medication puffs are reported as changes from baseline. For these outcomes, the posted comparison is a difference between group means. A mean difference is expressed in the original measurement units. Its sign depends on which group is subtracted from which; in these results, the comparison is described as omalizumab relative to placebo. The confidence interval for a mean difference indicates a range of values compatible with the data and analysis assumptions. For a difference scale, zero represents no mean difference.

The registry reports standard deviations for the arm-level changes. In general, a standard deviation describes the spread of individual observations around a group mean; it is not the same as the uncertainty in the mean or the confidence interval for a group difference. The derived comparisons are not described as adjusted analyses in the posted results. Their unadjusted p-values should be read as individual comparisons, especially because several outcomes were assessed.

How should the confidence intervals be understood?

In general, a confidence interval describes uncertainty in an estimate under a repeated-sampling framework and the assumptions of the statistical model. It is not a guarantee that the true value lies within the interval, nor does it describe the range of individual participant outcomes. For a rate ratio, the no-difference reference is 1; for a mean difference, it is 0. Whether an interval crosses its reference value is one way to assess the data’s precision relative to that no-difference point, but it is not a measure of clinical importance.

The primary outcome’s confidence interval is based on a model that accounts for time at risk and specified covariates. Confidence intervals for secondary results should be understood in light of the analysis methods and available reporting. The registry does not provide full details of all model diagnostics, all analysis code, or all missing-data procedures.

What do the planning illustrations estimate?

The sample-size illustrations use observed effects as planning inputs, with the effect set at the observed value or at stated fractions of it. The registry’s planning assumptions specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. For time-to-event tables the stated convention is total events; other tables give participants per arm. These are planning calculations, not results from the trial’s original design process. The trial’s own sample-size justification and original design assumptions are not reported in the registry record.

Power is the probability, under a specified alternative and statistical model, of detecting an effect at the chosen significance level. In a planning table, the 80% and 90% columns indicate the per-arm sample sizes associated with those target probabilities under the stated assumptions. They do not state the probability that the trial’s result is true or the chance that a particular finding arose by chance. The planning values are not observed power.

11. Confidence Intervals and Precision

The primary group-specific rates have 95% confidence intervals: 0.36 to 0.55 per patient for omalizumab and 0.49 to 0.83 per patient for placebo. These intervals show uncertainty around each modeled rate. They are not intervals for individual participants and should not be read as the range of outcomes a child might experience.

The primary rate ratio’s confidence interval has both limits below 1, the reference value for equal rates. That indicates that the reported interval for the relative comparison does not include equal estimated rates. Its breadth still matters: it allows a range of possible relative differences, rather than identifying one exact effect. The registry reports an unadjusted p-value of 0.041, but a p-value and a confidence interval convey different aspects of the analysis and should not be treated as interchangeable measures.

Precision depends on the event data, the number of participants and their time at risk, and the model assumptions. The primary comparison used a modified intent-to-treat population and a Poisson model adjusted for time at risk and specified covariates. The registry does not provide all diagnostics or missing-data procedures needed to independently assess the sensitivity of the interval to alternative assumptions.

For continuous secondary outcomes, intervals are expressed on a mean-difference scale, where zero represents no difference. For rate comparisons, the reference is 1. The nocturnal symptom-score interval is on one side of zero, while the rescue-medication-puff interval includes zero. These distinctions describe statistical precision, not whether a change is important to patients. The registry does not report a threshold for clinically meaningful change for these outcomes.

Confidence intervals also do not resolve uncertainty caused by multiple outcome testing or selective availability of results. The quality-of-life outcome is listed, but its results are not reported in the registry record. Accordingly, the precision of the posted estimates should be considered alongside the incompleteness of the outcome reporting and the lack of reported multiplicity procedures.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning illustrations estimate the participants needed under specified assumptions to detect a chosen effect. The non-time-to-event outcomes are expressed as participants per arm; the registry’s stated convention for time-to-event tables is total events. For these rate and continuous-outcome illustrations, the figures are participants per arm. The distinction matters: a per-arm figure applies separately to each comparison group, whereas a total-event figure counts events across the relevant groups.

The planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set to the observed effect or to a stated fraction of that observed effect. The 80% column gives the per-arm sample size associated with an 80% target probability of detecting that assumed effect under those assumptions; the 90% column gives the corresponding per-arm size for a 90% target probability. For example, for the primary rate outcome, the planning illustration for 100% of the observed effect gives 521 participants per arm for 80% power and 697 participants per arm for 90% power. For 75% of the observed effect, it gives 880 and 1,178 participants per arm, respectively. For 50% of the observed effect, it gives 1,885 and 2,524 participants per arm, respectively.

Smaller effects are harder to distinguish from random variation, so the planning illustrations require more participants per arm as the assumed effect becomes smaller. These calculations are not observed power. The registry’s original sample-size justification and the assumptions used in the trial’s own design are not reported in the registry record; the illustrations use the posted observed effect for planning purposes.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, λ₀ and λ₁ are event rates per patient-year, and T is follow-up per participant in years. This assumes Poisson counts and equal follow-up.

Worked calculation for this trial

1. Control rate λ₀ = 0.6400; treatment rate λ₁ = 0.4500 events per patient-year; follow-up T = 0.46 years.
2. n = (1.96 + 0.842)² × (1/0.6400 + 1/0.4500) / (0.46 × [ln(0.703)]²) = 520.6, rounded up to 521 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
lambda0 <- 0.64                      # control rate, events per patient-year
lambda1 <- 0.45                      # treatment rate
tt      <- 0.459946339593714                       # follow-up per participant, years
n_per_arm <- function(power, frac = 1) {
  l1 <- lambda0 * (lambda1 / lambda0)^frac   # smaller effect = fraction of the observed log rate ratio
  ceiling(round((z_a + qnorm(power))^2 * (1 / lambda0 + 1 / l1) / (tt * log(l1 / lambda0)^2), 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Simulation 1: Poisson counts. Simulation 2: over-dispersed counts (variance = 1.5 x mean), analysed with the matching variance.
set.seed(79937)
n    <- n_per_arm(0.80)
reps <- 20000
m0 <- lambda0 * n * tt; m1 <- lambda1 * n * tt
x0 <- rpois(reps, m0); x1 <- rpois(reps, m1)
z  <- log(x1 / x0) / sqrt(1 / x0 + 1 / x1)
cat(sprintf("Simulated power, Poisson counts, n = %s per arm: %.3f\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE)))
phi <- 1.5
y0 <- rnbinom(reps, mu = m0, size = m0 / (phi - 1)); y1 <- rnbinom(reps, mu = m1, size = m1 / (phi - 1))
z2 <- log(y1 / y0) / sqrt(phi * (1 / y0 + 1 / y1))
cat(sprintf("Simulated power, over-dispersed counts (phi = 1.5), same n: %.3f\n", mean(abs(z2) > z_a, na.rm = TRUE)))

Output from running the code

100% of observed effect: n per arm = 521 (80% power), 697 (90% power)
 75% of observed effect: n per arm = 880 (80% power), 1,178 (90% power)
 50% of observed effect: n per arm = 1,885 (80% power), 2,524 (90% power)
Simulated power, Poisson counts, n = 521 per arm: 0.806
Simulated power, over-dispersed counts (phi = 1.5), same n: 0.632

The first simulation draws Poisson counts and should land close to the target power. The second allows extra variability (variance 1.5 times the mean, a purely illustrative value), which lowers the power at the same sample size, so rate trials usually need more participants than the Poisson formula suggests.

14. Multiplicity, Missing Data and Analysis Populations

The record lists a primary endpoint and several secondary outcomes, but it does not report a multiplicity-control strategy for testing them. Multiplicity matters because evaluating several outcomes can increase the chance that one or more comparisons appear statistically notable even when the underlying differences are absent. In general, a prespecified testing hierarchy or adjustment procedure can help control that risk. Whether such a procedure was planned or used is not reported in the registry record.

The secondary results include unadjusted p-values, and the registry lists no reported analyses for those outcomes. The posted p-values should not be interpreted as if they had been adjusted for the number of comparisons. The registry also does not report whether outcomes were prioritized in a formal testing sequence or whether any secondary findings were intended to be confirmatory.

The primary population is described as modified intent-to-treat. It includes randomized participants except participants at 2 sites excluded for Good Clinical Practice non-compliance; the registry states that excluded participants were replaced at other sites. The primary outcome arm counts are 384 for omalizumab and 192 for placebo. The record does not provide a full participant flow or explain all differences between overall enrollment and the analysis counts.

Methods for handling missing outcome observations, withdrawals, or incomplete follow-up are not reported in the registry record. Nor are sensitivity analyses for missing data described. This leaves uncertainty about how incomplete outcome information may affect the estimates. Interim analyses, stopping rules, and the original sample-size justification are also not reported in the registry record. Their absence from the registry record should not be taken as evidence that a procedure was or was not used; it means that the posted information does not establish the details.

For the primary rate analysis, the record does specify a Poisson model, time at risk, and adjustment covariates. It does not describe all model diagnostics, the handling of potential extra-Poisson variation, or alternate-model sensitivity checks. Those details would help readers judge how dependent the interval and comparison are on modeling assumptions.

15. 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 (8.7%), pneumonia (2.9%), upper respiratory tract infection bacterial (1.0%), appendicitis (0.7%), diarrhoea (0.5%).

The registry reports serious adverse events for 421 participants at risk in the omalizumab group and 207 participants at risk in the placebo group. Serious adverse events affected 27 participants in the omalizumab group and 26 in the placebo group. These are participant counts with the stated at-risk denominators; they are not counts of every event, since one participant may experience more than one event. The record does not provide a comparative statistical analysis of these safety counts.

The listed serious adverse-event terms include asthma, reported as 8.7%, and pneumonia, reported as 2.9%. Other listed terms are upper respiratory tract infection bacterial, appendicitis, diarrhoea, and duodenal ulcer, with the percentages displayed in the registry record. The registry does not establish in this listing whether each term is attributable to treatment or whether the entries should be interpreted as group-specific comparisons.

Other adverse events affected 374 of 421 participants in the omalizumab group and 194 of 207 in the placebo group. The definition and analysis details for this other-event measure are not reported in the registry record. Deaths are not reported in the registry record. These counts describe the posted safety information; they do not by themselves establish comparative safety or causation.

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

The primary result is an estimate of the relative rate of clinically significant asthma exacerbations during a particular period in a defined trial population. In the registry analysis, the estimated rate was lower in the omalizumab arm than in the placebo arm, and the confidence interval for the rate ratio lay below the equal-rate reference. The posted unadjusted p-value was 0.041. This is evidence of a difference in the modeled rates under the analysis used, not a guarantee that the same estimate would occur in another study or population.

The result concerns investigator-judged worsening that met the registry’s treatment-escalation definition. It does not represent every asthma symptom, all exacerbations under any definition, or a direct measure of a participant’s overall experience. It also pertains to the 24-week fixed-dose steroid period, while the trial’s treatment period lasted 52 weeks. The separate 52-week exacerbation outcome is secondary and should be interpreted on its own terms.

The comparison does not establish the clinical importance of the estimated difference. The registry does not report a threshold for a meaningful change in exacerbation rate or for the symptom and medication-use measures. Nor does the result identify which individual participants benefited or experienced an event. Group-level rates and confidence intervals summarize the trial data; they do not predict an individual outcome.

The record’s interpretation is further bounded by its modified intent-to-treat population, exclusion of participants from 2 sites, and incomplete reporting of missing-data methods and multiplicity procedures. The outcomes were not all reported, and the record does not provide a full account of analysis decisions. These limitations do not erase the posted estimates, but they make clear that the estimates should be read in the context of the recorded design and reporting.

More broadly, a statistically distinguishable result is not equivalent to proof of a mechanism, a complete account of benefits and harms, or a recommendation about treatment. The registry results address a specific randomized comparison in children meeting the recorded eligibility description. They do not answer questions about other ages, asthma populations, treatment schedules, or outcomes not measured or reported in this record.

17. Why This Trial Matters Statistically

This trial illustrates why event rates and exposure time can matter in clinical research. The primary outcome was not simply whether a participant had an exacerbation; it was a rate per patient over a defined period, with person-days at risk accounted for in the model. That approach recognizes that event frequency and observation time both contribute to the comparison.

It also shows the importance of separating an estimate from its uncertainty. The registry reports group-specific rates, a rate ratio, a confidence interval, and an unadjusted p-value. Each communicates something different: the rates retain the outcome’s original scale, the ratio compares groups relatively, the interval describes uncertainty, and the p-value addresses compatibility with a null model under stated assumptions. None alone captures the full evidential picture.

The trial also has multiple relevant timeframes. Its primary endpoint covers the fixed-dose steroid period, while a secondary exacerbation endpoint spans the full treatment period. Those are not interchangeable analyses. Clear attention to endpoint timing helps prevent an estimate from being generalized to a period it does not describe.

Finally, the record demonstrates how registry reporting affects statistical interpretation. The primary model and analysis population are described, but multiplicity procedures, missing-data methods, original sample-size justification, and some secondary outcome results are not reported. Statistical readers need both the numerical estimates and the boundaries of what is documented. The planning illustrations can inform future design discussions, but they do not reconstruct the trial’s original design process or measure its observed power.

18. 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.
• Rate comparisons use a Poisson approximation unless the sponsor posted confidence limits; real event counts are often over-dispersed.

The primary result applies to the recorded modified intent-to-treat population, which excluded participants from 2 sites because of Good Clinical Practice non-compliance. Although the registry states that excluded participants were replaced at other sites, it does not provide a full participant flow or detailed information on the excluded participants. That limits assessment of the exclusions and of how the analysis population relates to all enrolled participants.

The primary endpoint has a specific investigator-judged definition requiring escalation of inhaled corticosteroid dose and/or systemic rescue corticosteroid treatment. Differences in clinical judgment or event ascertainment could affect which events qualify, but the record does not describe assessment consistency or adjudication procedures. The definition also means the result does not cover all symptom worsening or all reported asthma events.

The primary analysis uses a Poisson model adjusted for time at risk and listed covariates. The record does not provide model diagnostics, sensitivity analyses, or details about handling extra-Poisson variation. Missing-data procedures, withdrawal handling, and outcome-completeness information are also not reported in the registry record. These omissions limit independent assessment of the model and the robustness of the estimates.

The study includes multiple outcomes and timeframes, but multiplicity procedures are not reported. Results for the listed quality-of-life outcome are also not reported in the registry record. This makes the secondary evidence incomplete and complicates interpretation of the individual unadjusted p-values. The registry does not report the original sample-size justification, interim analyses, or the full statistical analysis plan.

Finally, the registry lists fluticasone as an intervention, while the available arm descriptions do not establish its precise role. The primary result should therefore be understood in the context of the recorded omalizumab-versus-placebo comparison and the described fixed steroid phase, without assuming additional protocol details not reported in the registry record.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Efficacy and Safety of Omalizumab in Children (6 - < 12 Years) With Moderate-severe, Inadequately Controlled Allergic Asthma — NCT00079937.
• Registry record last updated 2012-04-11; status last verified 2012-04.
• Results first posted 2011-08-03.
• 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.

22. Record Summary

NCT00079937 is a completed Phase 3 randomized, quadruple-masked, parallel-group, placebo-controlled trial sponsored by Novartis Pharmaceuticals. It enrolled 628 children aged 6 to < 12 years with moderate-to-severe, inadequately controlled allergic asthma. Omalizumab was compared with placebo over 52 weeks.

The primary outcome was clinically significant asthma exacerbation rate during the 24-week fixed-dose steroid period. The registry reports lower modeled rates for omalizumab than placebo, with a rate-ratio confidence interval below the equal-rate reference and an unadjusted p-value of 0.041. The primary analysis used a modified intent-to-treat population and a Poisson model adjusted for time at risk and specified covariates.

Secondary results cover symptoms, rescue medication, and exacerbations over 52 weeks; the listed quality-of-life outcome has no results reported in the registry record. Multiplicity and missing-data methods, the trial’s original sample-size justification, and interim analyses are not reported in the registry record.