Study of Efficacy and Safety of Xolair® (Omalizumab) in Chinese Patients With Chronic Spontaneous Urticaria: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Efficacy and Safety of Xolair® (Omalizumab) in Chinese Patients With Chronic Spontaneous Urticaria (NCT03328897), a randomized phase 3 study. The primary outcome is Change From Baseline of the Itch Severity Score (ISS7) Score After 12 Weeks of Treatment.

2. Clinical Question

The study record describes a comparison of efficacy and safety in patients whose symptoms persisted despite antihistamine therapy. The primary measure focuses specifically on itch severity, rather than treating the broader urticaria symptom burden as a single outcome. Both dose groups are compared with the same placebo group, and the reported primary analysis concerns change from baseline through Week 12. This is a question about the measured outcomes over the trial period; it does not by itself establish what results would be in other populations, treatment settings or follow-up periods.

3. Trial Design

This was a phase III, randomized, quadruple-masked, parallel-group study, listed as completed. The registry records enrollment of 418. The study began on 2017-04-26, and primary completion is recorded as 2019-07-23. Novartis Pharmaceuticals is listed as sponsor. The condition studied was chronic spontaneous urticaria.

Participants were assigned to omalizumab 300 mg, omalizumab 150 mg or placebo, as add-on treatment to H1 antihistamine therapy. The two active-treatment schedules and the placebo schedule involved injections every 4 weeks on Day 1, Week 4 and Week 8. At each scheduled treatment, the 300 mg group received two omalizumab injections; the 150 mg group received one omalizumab and one placebo injection; and the placebo group received two placebo injections. These descriptions indicate matching injection procedures across the listed arms, but details of how masking was maintained are not reported in the registry record.

The primary endpoint timeframe is baseline to Week 12. The primary outcome population is the Full Analysis Set. The registry lists several further symptom and quality-of-life outcomes, including itch, hives, urticaria activity and dermatology-related quality of life. More detailed eligibility criteria, allocation procedures, treatment adherence, follow-up beyond the stated outcome timeframes, and the trial’s original statistical plan are not reported in the registry record. The randomized parallel design supports comparison of the assigned groups, while masking can reduce some risks of bias in treatment delivery and outcome assessment; the record does not give enough detail to assess how these procedures were implemented.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: Patients were randomized into three treatment groups (omalizumab 300 mg s.c., omalizumab 150 mg s.c. and placebo) in a 2:2:1 ratio.

Randomized-treatment Epoch

Reasons for not completing this period:

Follow-up Epoch

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Full Analysis Set

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 of the Itch Severity Score (ISS7) Score After 12 Weeks of Treatment, measured over Baseline, Week 12.

The primary endpoint is change from baseline in the Itch Severity Score over 7 days (ISS7) after 12 weeks of treatment. Participants recorded itch severity twice daily in an eDiary on a scale from 0, none, to 3, intense or severe. The weekly score was derived from daily scores over the seven days before a visit. Its possible range was 0 to 21, with 0 representing the best score and 21 the worst. Complete itch response was defined as ISS7 = 0, but the primary endpoint is the continuous change in score, not the proportion achieving complete response.

A weekly measure can capture symptom burden across several days rather than relying on a single momentary report. Change from baseline describes how the score at follow-up differs from the participant’s baseline score. In this scale, a negative change indicates a reduction in recorded itch severity. Comparing that change between randomized groups helps distinguish improvement over time in the active-treatment groups from change also seen in the placebo group.

The endpoint is patient-recorded and specific to itch. It does not directly measure every aspect of chronic spontaneous urticaria, and a group mean change does not show the range of individual experiences. The registry lists the Full Analysis Set for this outcome. Further detail about the exact construction of the analysis set, handling of missing diary entries, and the clinical interpretation threshold for ISS7 change is not reported in the registry record.

7. Results Posted in the Registry

• Omalizumab 300mg: mean -10.11 versus -5.87 on control; difference -4.24 (95% CI -5.69 to -2.79), standardized effect d = -0.77; z-test p = <0.001.
• Omalizumab 150mg: mean -9.66 versus -5.87 on control; difference -3.79 (95% CI -5.24 to -2.34), standardized effect d = -0.69; z-test p = <0.001.

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 From Baseline of Urticaria Activity Score (UAS7) After 12 Weeks of Treatment

• 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 errors.
• Result:
  • Omalizumab 300mg: mean -21.82 versus -11.62 on control; difference -10.20 (95% CI -13.23 to -7.17), standardized effect d = -0.88; z-test p = <0.001.
  • Omalizumab 150mg: mean -20.74 versus -11.62 on control; difference -9.12 (95% CI -12.13 to -6.11), standardized effect d = -0.80; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Omalizumab 300mg than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Omalizumab 150mg than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Change From Baseline of Number of Hives Score (NHS7) After 12 Weeks of Treatment

• 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 errors.
• Result:
  • Omalizumab 300mg: mean -11.68 versus -5.76 on control; difference -5.92 (95% CI -7.58 to -4.26), standardized effect d = -0.93; z-test p = <0.001.
  • Omalizumab 150mg: mean -11.11 versus -5.76 on control; difference -5.35 (95% CI -7.00 to -3.70), standardized effect d = -0.85; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Omalizumab 300mg than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Omalizumab 150mg than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Percentage of Patients With UAS7≤6 at Week 12

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Omalizumab 300mg: 48.5% (81/167) versus 10.8% (9/83) on control; risk difference 37.7 percentage points (95% CI 27.6 to 47.8), risk ratio 4.47 (2.37–8.45); unadjusted two-proportion z-test p = <0.001.
  • Omalizumab 150mg: 47.3% (79/167) versus 10.8% (9/83) on control; risk difference 36.5 percentage points (95% CI 26.4 to 46.6), risk ratio 4.36 (2.31–8.25); unadjusted two-proportion z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Omalizumab 300mg than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Omalizumab 150mg than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The posted numeric secondary results follow a pattern broadly consistent with the primary outcome: the two omalizumab groups have larger average reductions in the reported continuous symptom measures than placebo, and more participants meet the posted UAS7 threshold at Week 12. This provides related evidence across itch and other symptom measures, while remaining distinct from the primary ISS7 analysis. The secondary outcomes address different aspects of urticaria and should not be treated as interchangeable measures.

The registry lists seven secondary outcome titles. Numeric results are posted for change in UAS7, change in NHS7, and the proportion with UAS7 ≤ 6. Results for percentage of complete responders, percentage meeting the ISS7 minimally important difference, change in DLQI, and time to ISS7 MID response are not reported in the registry record. The available secondary results therefore do not constitute a complete numeric account of every listed secondary outcome.

In general, secondary endpoints can help assess whether a pattern extends beyond the primary measure, but they commonly involve additional comparisons. When many outcomes are tested, unadjusted p-values do not control the overall chance of false-positive findings across the full set. The registry does not report whether multiplicity adjustments were applied to these secondary analyses, or how secondary outcomes were ordered or designated for confirmatory interpretation. Their results should consequently carry less weight than the primary analysis and be read as supportive rather than as independent confirmation.

These findings do not answer whether the two doses differ from each other: the posted comparisons are each against placebo. Nor do they establish effects beyond the listed timeframes. Their relation to the primary result is one of outcome-level consistency, not a replacement for the prespecified primary question.

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

• Change From Baseline of Urticaria Activity Score (UAS7) After 12 Weeks of Treatment
• Change From Baseline of Number of Hives Score (NHS7) After 12 Weeks of Treatment
• Percentage of Patients With UAS7≤6 at Week 12
• Percentage of Complete Responders (UAS7 = 0) at Week 12
• Percentage of Patients With ISS7 Minimally Important Difference (MID) at Week 12
• Change From Baseline of Dermatology Life Quality Index (DLQI) Score After 12 Weeks of Treatment
• Time to ISS7 MID Response by Week 12

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous: it is measured on a numerical scale, and the registry reports estimated mean changes. A mean summarizes the center of the group’s measured values. It does not imply that every participant changed by that amount, nor does it describe the full spread of individual outcomes. The reported arm estimates are least-squares means, which are model-based estimates rather than simple raw averages. The registry gives standard errors as the measure of their uncertainty.

What does the repeated-measures model do?

The sponsor used a Mixed Model with Repeated Measures (MMRM) for the primary comparisons. In general, repeated-measures models analyze observations collected at multiple time points while accounting for the fact that measurements from the same participant are related. Such models can use the pattern of recorded follow-up measurements to estimate group differences over time. The exact model specification, covariance structure, covariates, and missing-data assumptions are not reported in the registry record, so they cannot be assessed from the posted information.

The sponsor’s reported quantity is a net mean difference between an omalizumab group and placebo. A negative estimate corresponds to a larger reduction in ISS7 in the omalizumab group, because a lower score indicates less itch. The analysis reports a 95% confidence interval and a p-value for each comparison. The sponsor identifies each result as a superiority analysis, meaning the stated analysis tested whether the groups differed in the direction specified by the trial analysis.

How should the re-calculations be understood?

The simple re-calculations use the posted arm-level estimates and their standard errors to make unadjusted comparisons. For the primary endpoint, the estimated differences are -4.24 and -3.79 for the two active groups versus placebo. These calculations are not the MMRM. The pooled standard deviations used for standardized effect summaries are approximate because they are inferred from the posted standard errors, rather than reported as the observed individual-level standard deviations. They offer a simple scale for comparing the size of an estimated difference with variability, but should not be treated as model-adjusted trial estimates.

The re-calculated p-values are unadjusted and do not account for the many outcomes and comparisons listed in the record. They are not a substitute for the sponsor’s reported analysis, which is based on the named repeated-measures model. Since the record does not identify a discrepancy, the re-calculations can be read as broadly checking the scale of the reported comparisons. When the sponsor’s own analysis is available, that analysis takes precedence.

What do p-values say?

In general, a p-value measures how unusual data at least as incompatible with a specified null hypothesis would be if that hypothesis and the analysis assumptions were true. A small p-value is not the probability that the null hypothesis is true, and it does not quantify the chance that the result is a false positive. The reported p-values of < 0.001 indicate strong statistical evidence against a zero difference under the sponsor’s analysis assumptions. They do not, by themselves, establish clinical importance, eliminate bias, or account for all possible analyses.

In general, a confidence interval gives a range of values reasonably compatible with the data and model at its stated confidence level. Its width reflects statistical precision: narrower intervals indicate more precise estimates, while wider intervals leave greater uncertainty about the effect’s size. A 95% interval is not a guarantee that the true value lies in the particular interval observed. Its interpretation depends on the analysis assumptions and on how the endpoint and comparisons were selected.

Why does the design matter?

Random assignment aims to make treatment groups comparable with respect to both measured and unmeasured characteristics, on average. Masking can reduce the influence of treatment knowledge on behavior, care or assessment. These design features strengthen a between-group comparison, but they do not guarantee that every source of bias is absent. The registry record does not describe the randomization procedure or masking implementation in enough detail to evaluate those safeguards further.

The primary outcome is one among multiple outcome measures, and the record lists two dose comparisons against placebo. In general, testing many outcomes or contrasts increases the opportunity to observe a nominally small p-value by chance. Whether and how the sponsor controlled this risk is not reported in the registry record. Accordingly, unadjusted exploratory calculations and secondary findings should be interpreted more cautiously than a prespecified primary analysis with a fully reported multiplicity plan.

11. Confidence Intervals and Precision

The sponsor-reported 95% confidence interval for the 300 mg comparison is -5.70 to -2.77, around a mean difference of -4.23. For the 150 mg comparison, it is -5.24 to -2.33, around a mean difference of -3.79. Both intervals are entirely below zero. Under the stated model, the intervals therefore support a negative between-group difference in change in ISS7, consistent with a greater reduction in the omalizumab groups than in placebo.

The intervals also communicate uncertainty about the magnitude of the estimated differences. They do not pinpoint a single effect, and the range should not be interpreted as covering individual participant responses. The 300 mg and 150 mg intervals overlap. Overlap is not itself a formal test comparing the doses; the registry does not report a direct dose-to-dose analysis. Nor does the interval establish whether the difference crosses a threshold of clinical importance, because an ISS7 minimally important difference is not reported in the registry record.

The simple re-calculated intervals are -5.693 to -2.787 for 300 mg and -5.236 to -2.344 for 150 mg. These are unadjusted approximations based on summary statistics. The sponsor’s MMRM intervals are the relevant model-based results for the main interpretation. Differences in the last displayed digits between the two sets reflect the different calculation approach and rounding, not a reported discrepancy.

In general, precision depends on the amount of information and variability in the data, as well as the model. The standard errors reported for the arm-level least-squares means provide another indication of estimation uncertainty, but they do not replace the confidence intervals for the between-group comparisons. The registry does not report all model details or individual-level distributions, limiting independent assessment of the uncertainty calculation.

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 figures are illustrations based on the observed effect, not the trial’s original design assumptions. For these continuous and binary outcomes, the figures refer to participants per arm, not total events. The planning assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Each scenario uses the stated fraction of the observed effect as the effect to detect. The trial’s own original sample-size justification and design assumptions are not reported in the registry record.

The 80% power column gives the estimated participants per arm for a hypothetical study to have an 80% chance of detecting the stated effect, if that effect and the planning assumptions were correct. The 90% power column gives the corresponding estimate for a 90% chance. These are prospective planning quantities, not evidence about the probability that the completed trial’s result is correct. They are not observed power.

Each row scales the effect being planned for: planning for 75% or 50% of the observed effect means targeting a smaller difference than the one estimated in this trial. Smaller effects are harder to distinguish from random variation, so they require more participants under the same assumptions. Conversely, using the full observed effect for planning can produce a smaller illustrative sample size, but the observed effect is uncertain and may not recur in another study.

The calculations compare two arms with equal allocation. The actual trial had three groups and unequal group sizes as recorded for the primary analysis, so the illustrations do not reproduce the trial’s allocation or statistical model. They are useful for understanding how assumptions about effect size and desired power influence planning, not as a retrospective explanation of why the trial enrolled its recorded number of participants.

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, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -4.240; pooled standard deviation σ = 5.539.
2. n = 2 × (1.96 + 0.842)² × 5.539² / -4.240² = 26.8, rounded up to 27 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
delta <- -4.24                      # observed difference in means
sigma <- 5.53898772922599                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^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 = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(3328897)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 27 (80% power), 36 (90% power)
 75% of observed effect: n per arm = 48 (80% power), 64 (90% power)
 50% of observed effect: n per arm = 108 (80% power), 144 (90% power)
power.t.test: 27.8 
Simulated power at n = 27 per arm: 0.791 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The sponsor’s primary analysis used a Mixed Model with Repeated Measures. It reported a mean difference of -4.23 for omalizumab 300 mg versus placebo, with a 95% confidence interval from -5.70 to -2.77 and p < 0.001. For omalizumab 150 mg versus placebo, it reported -3.79, with a 95% confidence interval from -5.24 to -2.33 and p < 0.001.

The simple re-calculation from the posted summary statistics gives -4.24 for the 300 mg comparison and -3.79 for the 150 mg comparison. Its intervals are -5.693 to -2.787 and -5.236 to -2.344, respectively, with unadjusted p-values of < 0.001 for both comparisons. These estimates are close to the sponsor’s reported results. The re-calculation is a simple unadjusted check based on summary information and does not reproduce the MMRM.

The registry does not flag a discrepancy between the results. The sponsor’s model-based analysis therefore remains the primary result for interpretation; the re-calculation is supplementary and should not be substituted for it. The record does not provide enough detail to independently reproduce the MMRM or assess all of its assumptions.

15. Multiplicity, Missing Data and Analysis Populations

The record identifies one primary outcome and lists multiple secondary outcomes, with comparisons of each omalizumab dose against placebo. Testing several outcomes and contrasts creates a multiplicity issue: in general, the more hypotheses examined, the greater the chance that at least one result appears statistically significant by chance, even if each individual test uses a conventional threshold. The registry record does not report a multiplicity-control procedure, an overall testing hierarchy, or whether secondary comparisons were intended to be confirmatory. The primary p-values should therefore be distinguished from the collection of secondary results.

The primary outcome is identified as belonging to the Full Analysis Set. The record does not describe the exact membership rules for that set, whether all randomized participants were included, or how participants with missing outcome measurements were handled. It also does not state the assumptions or sensitivity analyses used for missing data in the MMRM. In general, repeated-measures models can use available observations, but the validity of inference depends on model assumptions about the data that are missing. Those assumptions cannot be evaluated from the registry record.

The registry names MMRM for the primary endpoint and reports its estimated differences, confidence intervals and p-values. Further details about model covariates, covariance structure, estimation method, prespecified contrasts, and sensitivity analyses are not reported in the registry record. The record also does not report an interim analysis plan or whether interim analyses were conducted. Their absence from the record should not be taken as evidence that a procedure was or was not used.

Randomization and quadruple masking are recorded, but the method of sequence generation, concealment, and practical implementation of masking is not described. In general, randomization protects comparisons against systematic baseline differences, while masking can limit bias in care and outcome assessment. The degree to which these safeguards were achieved cannot be fully judged from the available descriptions. These reporting gaps affect how confidently the statistical assumptions and risk of bias can be assessed; they do not alter the numerical results reported for the primary analysis.

16. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 2% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: lumbar vertebral fracture (1.2%), meniscus injury (1.2%), embolism venous (1.2%), vertigo positional (0.6%), pelvic inflammatory disease (0.6%).

The registry reports serious adverse events for each group: 5 among 167 participants at risk in the omalizumab 300 mg group, 5 among 167 in the omalizumab 150 mg group, and 3 among 83 in the placebo group. Deaths are recorded as 0 in each group. These are the serious-event counts and at-risk denominators reported in the record; they are not a statistical test of comparative safety.

Other adverse events are reported as 84 among 167 at risk in the 300 mg group, 79 among 167 in the 150 mg group, and 43 among 83 in the placebo group. The registry also lists serious-event terms with percentages, including Lumbar vertebral fracture at 1.2%, Meniscus injury at 1.2%, Embolism venous at 1.2%, Vertigo positional at 0.6%, Pelvic inflammatory disease at 0.6%, and Upper respiratory tract infection at 0.6%. The record does not specify in this summary how those terms are distributed by treatment arm.

These counts describe events recorded during the study and do not establish whether an event was caused by treatment. The registry does not report comparative statistical analyses of adverse events, event timing, exposure-adjusted rates, or detailed definitions and ascertainment procedures. Consequently, the figures are descriptive and should be interpreted alongside those limitations.

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

The primary result describes an average between-group difference in change in itch severity over the trial’s 12-week treatment period. The sponsor’s reported estimates are negative for both omalizumab doses versus placebo, and both 95% confidence intervals lie below zero. In the context of the ISS7 scale, that direction corresponds to a larger average reduction in recorded itch severity in the omalizumab groups. It is a comparison of group averages, not a prediction of what any one participant experienced.

The result does not by itself establish the clinical importance of the difference. A minimally important difference for the primary ISS7 outcome is not reported in the registry record. Nor does a small p-value describe the size of benefit, the probability that an individual will respond, or the likelihood of an adverse event. Statistical evidence and clinical interpretation are related but distinct questions.

The primary analysis is specific to adults with chronic spontaneous urticaria who remained symptomatic despite H1 antihistamine therapy, the treatments and doses recorded, and the stated follow-up. The result cannot establish effects in populations not described by the record, with different background care, or over a longer period. The record’s serious-event counts are descriptive and do not prove or rule out a causal relationship with treatment.

The posted comparisons do not directly test whether 300 mg differs from 150 mg. Both doses are compared with placebo, and the registry does not report a dose-to-dose test. In addition, incomplete reporting of multiplicity procedures, missing-data methods and model specifications limits a full assessment of the analysis. The evidence should therefore be understood as the sponsor’s reported randomized comparison for the primary endpoint, together with the stated uncertainty and reporting limitations, rather than as a universal or individual-level conclusion.

18. Why This Trial Matters Statistically

This trial offers a useful example of how a registry result connects a patient-reported symptom measure to a model-based comparison. ISS7 is built from twice-daily itch entries over a week, and the primary result compares change from baseline between randomized groups. The negative mean differences make the direction of the contrast interpretable in light of the scale: lower scores mean less severe itch.

It also illustrates why the sponsor’s analysis and a simple re-calculation should not be conflated. A repeated-measures model can use longitudinal information, whereas the re-calculation is an unadjusted approximation from posted summary statistics. The close estimates provide a useful check, but the model-based result is the relevant reported analysis. Confidence intervals add information about precision that a p-value alone cannot convey.

The record also highlights the importance of separating a primary endpoint from multiple secondary outcomes. Related symptom results can add context, but unadjusted tests across many outcomes require caution, especially when the multiplicity plan is not reported. Likewise, safety counts are informative descriptions but do not constitute comparative causal analyses.

Finally, planning illustrations based on an observed effect are not explanations of the original trial design and are not observed power. They show how smaller target effects require larger planned groups under stated assumptions. Keeping these distinctions clear helps readers assess what the posted statistics support, where uncertainty remains, and which details are unavailable in the registry record.

19. 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 primary assessment is at Week 12, and longer-term symptom outcomes are not reported in the registry record. The record describes treatment visits on Day 1, Week 4 and Week 8, but does not provide details about subsequent follow-up for the outcomes discussed. As a result, the primary findings characterize the stated short-term endpoint and do not establish whether differences persist.

The study concerns adults with chronic spontaneous urticaria who remained symptomatic despite antihistamine therapy, but more complete eligibility criteria and participant characteristics are not reported in the registry record. This limits assessment of how well the enrolled group represents other clinical populations. The registry identifies the primary outcome population as the Full Analysis Set without supplying its detailed definition.

Important analytical details are not reported, including the model’s full specification, missing-data assumptions, sensitivity analyses and multiplicity procedures. The primary endpoint relies on patient eDiary reports; the record does not describe completeness of diary data or how missing entries were handled. The simple re-calculations use approximate variability inferred from standard errors and are not a substitute for individual-level or model-based analyses.

The two active groups are each compared with a shared placebo group, but a direct comparison between the doses is not reported. The record also provides descriptive adverse-event counts without comparative safety modeling or detailed exposure information. Serious-event term percentages are listed without arm-specific attribution in the summary. These reporting limits constrain conclusions about dose differences and comparative safety, even though the primary endpoint analyses and group-level counts are posted.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Study of Efficacy and Safety of Xolair® (Omalizumab) in Chinese Patients With Chronic Spontaneous Urticaria — NCT03328897.
• Registry record last updated 2020-11-04; status last verified 2020-10.
• Results first posted 2020-11-04.
• 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.

23. Record Summary

NCT03328897 is a completed phase III randomized, quadruple-masked, parallel-group study sponsored by Novartis Pharmaceuticals. It evaluated omalizumab 300 mg and 150 mg, compared with placebo, as add-on treatment to H1 antihistamines in adults with chronic spontaneous urticaria who remained symptomatic despite antihistamine therapy. Recorded enrollment was 418; the study began on 2017-04-26 and primary completion was 2019-07-23.

The primary endpoint was change from baseline in ISS7 after 12 weeks. The sponsor-reported MMRM estimated mean differences versus placebo of -4.23 for 300 mg and -3.79 for 150 mg, with p < 0.001 for each. The posted secondary results include symptom outcomes, while several listed secondary endpoints lack numeric results in the registry record. Serious adverse events and deaths are reported descriptively. Details of multiplicity control, missing-data handling and several model specifications are not reported.