Efficacy and Safety Study of RAGWITEK™ (MK-3641) in Children With Ragweed-Induced Rhinoconjunctivitis With or Without Asthma (MK-3641-008): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy and Safety Study of RAGWITEK™ (MK-3641) in Children With Ragweed-Induced Rhinoconjunctivitis With or Without Asthma (MK-3641-008) (NCT02478398), a randomized phase 3 study. The primary outcome is Total Combined Score (TCS) During the Peak Ragweed Season (RS).

2. Clinical Question

The trial addressed a combined measure rather than symptoms alone. That distinction matters because a participant's score incorporates both reported allergy symptoms and use of specified rescue medications. The primary comparison therefore concerns the average burden represented by this combined measure during the defined peak-season period, not a separate claim about each component or about outcomes outside that period.

The registry record describes children with ragweed-induced allergic rhinitis or rhinoconjunctivitis, including children with or without asthma. It does not report further eligibility details in the registry record for this analysis, so other characteristics of the enrolled population should not be inferred. The primary analysis population was restricted to treated participants with at least one relevant e-diary entry for the measurement and timeframe.

3. Trial Design

This was a phase III, randomized, placebo-controlled, triple-masked, parallel-group clinical trial. The registry lists enrollment of 1025 and a completed status. The recorded study start was 2015-07-20, and primary completion was 2018-11-09. These dates describe the registry record and do not, by themselves, explain the duration of participation for an individual child.

The two main groups received either short ragweed pollen allergen extract or placebo as a daily sublingual tablet for up to 35 weeks. Both groups could use study-provided rescue medications as needed to treat rhinoconjunctivitis symptoms. The registry also lists self-injectable epinephrine and several rescue or symptom-management medications among the interventions. Their presence in the record does not mean that each was assigned as a randomized study treatment.

Randomization assigns participants to study groups by chance, while masking is intended to limit the influence of treatment knowledge on participants, study personnel, or outcome assessment. The record labels masking as triple but does not identify the masked roles in the information. A parallel design means the groups were compared over the study rather than participants crossing from one assigned treatment to the other.

The primary outcome was assessed in the 15-day period during ragweed season with the highest moving pollen average. The primary analysis population included treated participants with at least one e-diary entry for the relevant outcome and period. The original sample-size justification, planned allocation ratio, detailed masking procedures, and the full protocol-level analysis plan 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: The analysis population includes all treated participants w/ ≥1 e-diary entry for the specified measurement and timeframe.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Baseline characteristics are reported for all treated participants.

6. Primary Endpoint

The registry lists the primary outcome as Total Combined Score (TCS) During the Peak Ragweed Season (RS), measured over The 15-day period during the ragweed season with the highest moving pollen average.

The primary endpoint was average Total Combined Score during peak ragweed season. The measure adds the daily rhinoconjunctivitis symptom score to the daily medication score. Symptoms were assessed across 6 allergy symptoms on a scale from 0 to 3 per symptom, with a symptom-score range of 0-18. The medication score was based on use of loratadine, olopatadine, and mometasone and had a score range of 0-20. The combined score could range from 0 to 38; lower values indicate fewer reported symptoms and less use of those rescue medications.

The endpoint was averaged over the 15 consecutive ragweed-season days with the highest 15-day average pollen count. Focusing on the peak season gives the comparison a defined period when pollen exposure was highest according to the trial's moving-average definition. It is not an average across every day of the year, nor does it measure all possible consequences of allergic disease.

A combined endpoint can reflect changes in symptoms, medication use, or both. It gives a single summary of those two related dimensions, but a total alone does not show how much each component contributed. The registry also reports symptom and medication components as secondary outcomes. Data were collected through an electronic diary completed by the participant, parent, or guardian, so the recorded score depends on those diary entries.

7. Results Posted in the Registry

• Short Ragweed Pollen Allergen Extract: mean 4.39 versus 7.12 on control; difference -2.73 (95% CI -3.50 to -1.96), standardized effect d = -0.45; 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.

Average TCS During the Entire RS

• 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:
  • Short Ragweed Pollen Allergen Extract: mean 3.88 versus 5.75 on control; difference -1.87 (95% CI -2.50 to -1.24), standardized effect d = -0.37; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Short Ragweed Pollen Allergen Extract than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Average Rhinoconjunctivitis (RC) DSS During the Peak RS

• 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:
  • Short Ragweed Pollen Allergen Extract: mean 2.55 versus 3.95 on control; difference -1.40 (95% CI -1.84 to -0.96), standardized effect d = -0.40; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Short Ragweed Pollen Allergen Extract than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Average Rhinoconjunctivitis (RC) DMS During the Peak RS

• 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:
  • Short Ragweed Pollen Allergen Extract: mean 2.01 versus 3.85 on control; difference -1.84 (95% CI -2.68 to -1.00), standardized effect d = -0.27; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Short Ragweed Pollen Allergen Extract than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The available continuous secondary results follow the same broad direction as the primary comparison: the extract group has lower posted scores than placebo on the entire-season combined score and on the peak-season symptom and medication components. Lower values are defined as less symptom burden, less medication use, or both, depending on the measure. The sponsor-reported tests for these continuous measures have p < 0.001. These results give context to the primary score, but they are related outcomes rather than wholly independent replications.

The component results help show that the combined endpoint is not the only measure recorded. Still, the primary score adds symptom and medication information, and the peak-season component measures use the same underlying domains. The entire-season combined score changes the timeframe but remains closely related to the peak-season score. Correlation among related outcomes means that several nominally significant results should not be treated as several independent demonstrations.

The registry lists additional secondary outcomes concerning local application-site reactions, anaphylaxis or systemic allergic reactions, and epinephrine treatment. Numerical results for those listed measures are not reported in the registry record details used. The presence of an outcome title is not evidence about the number of events or a difference between groups.

Unadjusted secondary results carry less weight when many outcomes are tested because the chance of at least one apparently noteworthy result can increase across multiple tests. Whether and how the trial controlled multiplicity is not reported in the registry record. The secondary findings are therefore best read as supportive context for the primary outcome, not as independently definitive conclusions. This does not change their observed direction; it limits the strength of claims drawn from multiple tests without a reported adjustment strategy.

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

• Average TCS During the Entire RS
• Average Rhinoconjunctivitis (RC) DSS During the Peak RS
• Average Rhinoconjunctivitis (RC) DMS During the Peak RS
• Percentage of Participants Reporting Pre-specified Local Application Site Reactions
• Percentage of Participants Reporting Anaphylaxis and/or Systemic Allergic Reactions
• Percentage of Participants Treated With Epinephrine

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous: each participant's daily symptom and medication scores are combined and averaged over the defined peak-season period. The registry reports group estimates and an analysis of the difference between them. Because lower scores indicate less symptom burden and medication use, a negative extract-versus-placebo difference favors a lower average score in the extract group on this scale. This wording describes the direction of the observed score comparison, not a treatment recommendation.

What does a group mean represent?

A mean summarizes a group's observations with one central value. It can be useful for comparing average scores, but it does not describe the spread of individual scores or show how many participants had values above or below a particular threshold. The registry identifies the primary parameter as a least-squares mean. In general, a least-squares mean is a model-based group estimate rather than necessarily the raw arithmetic average. The registry entries do not provide enough detail to reconstruct all adjustments used for that estimate.

The primary analysis is reported as ANOVA, or analysis of variance. In general, ANOVA is a method for comparing group means within a statistical model. The registry reports a mean difference, confidence interval, and p-value for the comparison. It labels the analysis as a superiority test. The detailed model specification, including any covariates or handling choices beyond what is stated, is not reported in the registry record.

What does the p-value tell the reader?

A p-value measures how compatible the observed data are with a specified null hypothesis under the assumptions of the statistical test. It is not the probability that the null hypothesis is true, nor does it measure the probability that the result occurred by chance in a general sense. The primary p-value is reported as p < 0.001. That indicates the test result is inconsistent with the null comparison at that threshold under the reported analysis, but it does not by itself communicate the size or practical importance of the difference. The estimated difference and its confidence interval provide complementary information.

Why can model choice matter?

The registry uses a different method for the peak-season medication-score comparison: a zero-inflated log-normal model. In general, a zero-inflated model can represent a measure with a distinct process producing zero values and a separate distribution for positive values; the log-normal component is used for positive values that are skewed on the original scale. This kind of approach can be relevant when a score has many zero observations or a non-symmetric distribution. The registry does not report the observed zero frequency or full diagnostic evidence for this choice. The method label should therefore be treated as a description of the reported analysis, not as proof of any particular data-distribution feature.

For some comparisons, simple unadjusted recalculations are also available from the posted group summaries. Such recalculations use summary information and are not a substitute for the sponsor's model-based analysis. The reported primary estimate and p-value come from the registry's ANOVA analysis. The recalculated figures are useful as a check on the broad direction and scale of the comparison, but they may not reproduce a model-based analysis that uses information or assumptions absent from the summary statistics.

How should the outcome's construction be kept in view?

The combined score is made from symptom and medication components, and both are collected through an e-diary completed by the participant, parent, or guardian. In general, diary measures can capture repeated reports over time, but their completeness and accuracy depend on entries being made. The registry specifies that the primary analysis population included treated participants with at least one e-diary entry for the relevant measure and timeframe. It does not report the detailed missing-data method, the extent of missing diary entries, or sensitivity analyses for missing outcomes.

These methods answer different questions. The score definition says what was measured; the model specifies how the reported comparison was estimated; the confidence interval describes precision; and the p-value addresses compatibility with a null comparison under test assumptions. None alone establishes the clinical importance of the result. Interpreting the findings requires considering all of these elements together, while distinguishing posted analysis from simpler recalculation and avoiding assumptions about unreported protocol details.

11. Confidence Intervals and Precision

The primary sponsor-reported mean difference was -2.73, with a 95% confidence interval from -3.45 to -2.00. The interval is wholly below zero, consistent with the reported direction of a lower average combined score in the extract group. The p-value for the reported comparison was p < 0.001. The interval gives a range of values compatible with the data and analysis under the usual confidence-interval framework; it is not a guarantee that the true value lies within this particular realized interval.

The posted group estimates were 4.39 for the extract group, with a 95% interval from 3.85 to 4.94, and 7.12 for placebo, with a 95% interval from 6.57 to 7.67. These intervals describe uncertainty around each group's reported estimate. They should not be used in place of the interval for the between-group difference: precision for a contrast depends on the joint comparison, not just on inspecting each group interval separately.

In general, a narrower confidence interval indicates greater precision about an estimated quantity, while a wider interval leaves more uncertainty about its possible value. Precision is not the same as absence of bias, and an interval does not convey how scores were distributed among individual participants. Here, the primary comparison interval communicates uncertainty on the score-difference scale, not a range of individual treatment responses.

The registry reports a confidence interval for the sponsor's ANOVA comparison. Recalculation from posted summary statistics gives a related unadjusted comparison, but it is not the same procedure as the sponsor's model-based analysis. The comparison should therefore be interpreted primarily from the sponsor-reported estimate and interval. The registry does not report a protocol-defined threshold for a clinically important difference, so statistical precision alone cannot establish the clinical importance of the observed score contrast.

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 participants per arm, not total trial enrollment and not total events. They are illustrative calculations based on the observed effect, not the original trial's design justification. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The calculation considers detecting the stated fraction of the observed effect. The original sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the number of participants per arm that the planning calculation estimates would be needed to have an 80% probability of detecting the specified effect under those assumptions, if that effect and assumptions held. The 90% power column expresses the same idea with a higher target probability of detecting the specified effect. Power is a property of a planned study under assumed conditions; it does not describe certainty about the observed result.

Each planning row uses a different fraction of the observed effect. Planning for 100% of the observed effect uses the full estimated contrast as the target. Planning for 75% or 50% uses a smaller target effect. Smaller effects are harder to distinguish from sampling variation, so the calculations require more participants per arm to achieve the same target power. The figures are illustrations, not evidence that a future study will reproduce the observed effect or meet its target.

These numbers are not observed power. They do not calculate the probability that the completed trial's result is true, and they do not replace the reported estimate, confidence interval, or test. The curve and figures should be read as planning aids tied to their stated assumptions, not as a retrospective judgment about the trial's success or adequacy.

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 = -2.730; pooled standard deviation σ = 6.083.
2. n = 2 × (1.96 + 0.842)² × 6.083² / -2.730² = 77.9, rounded up to 78 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 <- -2.73                      # observed difference in means
sigma <- 6.08261661089287                     # 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(2478398)
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 = 78 (80% power), 105 (90% power)
 75% of observed effect: n per arm = 139 (80% power), 186 (90% power)
 50% of observed effect: n per arm = 312 (80% power), 418 (90% power)
power.t.test: 78.9 
Simulated power at n = 78 per arm: 0.794 (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 registry's own primary analysis is an ANOVA comparison of final values. It reports a mean difference of -2.73, a 95% confidence interval from -3.45 to -2.00, and p < 0.001. This is the sponsor-reported inferential result and should be distinguished from a simple recalculation using posted group summaries.

The unadjusted recalculation from the primary group summaries also estimates a mean difference of -2.73 and reports p < 0.001. The close agreement in the point estimate supports the same broad description of the observed contrast: the extract group's average score is lower than placebo's. A recalculation based on summary statistics does not reproduce every feature of the sponsor's analysis, however, and its uncertainty calculation can differ from a model-based result.

For the primary endpoint, the registry record does not flag a discrepancy between the recalculation and the sponsor result. The sponsor analysis remains the source for the reported primary inference because it is the analysis recorded for the trial, while recalculation is a secondary statistical check. The registry does not report enough model detail to independently reproduce every part of the sponsor's ANOVA.

Similar distinctions apply to secondary comparisons: reported analyses use the methods identified by the registry, whereas recalculated results are simple unadjusted estimates from group summaries. When a method or estimate differs, it should not be resolved by silently substituting the simpler calculation for the trial's reported analysis.

15. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when a study evaluates several outcomes, timeframes, or comparisons. In general, the more statistical tests performed, the greater the opportunity for some results to appear statistically significant even when the corresponding effects are absent. A prespecified testing hierarchy or adjustment procedure can address this issue, but the registry entries do not report whether such a procedure was used for the primary and secondary outcomes. The multiplicity strategy is not reported in the registry record.

The primary endpoint is clearly identified, and the registry reports a primary ANOVA result. It also lists six secondary outcomes, including related symptom and medication measures and safety outcomes. The secondary results should not be treated as if each were an isolated confirmatory test when the overall testing plan is unavailable. In particular, related measures may share information because they assess overlapping components or time periods.

The primary analysis population is described as treated participants with at least one e-diary entry for the specified measurement and timeframe. This is an important qualification: the primary summary is not simply described as including every randomized participant regardless of diary availability. The registry entries do not report how many randomized participants lacked an eligible entry, how much diary data were missing, or the detailed method for handling missing measurements.

Missing outcome data can affect estimates if the availability of observations is related to scores or group assignment. In general, analysts may use assumptions or sensitivity analyses to examine how missingness could influence conclusions. The registry record details used do not report the assumptions behind missing-data handling or sensitivity analyses, so the impact of missing diary entries cannot be assessed from these registry entries alone.

The record also does not report the full statistical analysis plan, the original sample-size justification, or interim-analysis procedures. Those items should be treated as not reported in the registry record rather than inferred from the final results. The uncertainty about these details does not erase the posted primary estimate; it defines what can and cannot be independently evaluated about the trial's statistical planning and robustness.

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 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 (0.6%), abdominal pain (0.2%), hypersensitivity (0.2%), viral infection (0.2%), conduct disorder (0.2%).

The registry reports serious adverse events for participants at risk in each group: 7 affected participants among 513 at risk in the extract group and 9 among 509 at risk in placebo. Deaths were reported as 0 in each group. These figures describe the registry's serious adverse event reporting and should not be interpreted as a complete description of every safety outcome or every event experienced during the trial.

For other adverse events, the record reports 370 affected among 513 at risk in the extract group and 233 among 509 at risk in placebo. These are counts of participants affected as recorded, not a severity comparison and not a causal assessment. The serious-event counts are separate from the counts for other adverse events; they should not be combined into a new total.

Serious adverse event terms listed in the record include asthma, abdominal pain, hypersensitivity, viral infection, conduct disorder, and viral gastroenteritis, with percentages reported beside those terms. The registry entries do not supply detailed event narratives, timing, recurrence, or attribution for these terms. The listed counts therefore do not establish that an event was caused by study treatment. Safety findings should be read as recorded observations within the trial, alongside the limits of the reported details.

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

The primary result describes a lower mean combined symptom-and-medication score in the short ragweed pollen allergen extract group than in placebo during the defined peak ragweed-season period. The sponsor's reported mean difference was -2.73, with a 95% confidence interval from -3.45 to -2.00 and p < 0.001. This is an estimate of a group-average contrast for the specified measure and analysis population.

It does not mean that every participant in the extract group had a lower score than every participant in the placebo group, or that every child's symptoms or medication use changed in the same way. Group averages conceal variation among individuals. Nor does a combined score reveal the contribution of symptom reduction versus medication use; the component measures are needed to describe those dimensions separately.

The result is specific to the trial's endpoint definition, its 15-day peak-season period, and the children represented by the study's eligibility description. It is not a direct measurement of outcomes in all seasons, of long-term outcomes beyond the described study period, or of every consequence of allergic rhinitis or rhinoconjunctivitis. The registry does not provide a threshold for interpreting how large a score difference must be to be clinically important.

Statistical significance and clinical importance are related but distinct ideas. The reported p-value indicates evidence against the null comparison under the model and assumptions, while the estimate and interval convey the scale and precision of the contrast. Neither establishes an individual's expected outcome or guarantees the same result in another setting. The result should therefore be read as evidence about the recorded group comparison, not as individualized medical guidance.

The safety figures are also descriptive of recorded events in the trial and do not by themselves establish causation. Some listed secondary outcomes lack numerical results in the registry entries used here, and details of multiplicity and missing-data handling are not reported. Those limits define the scope of conclusions that can be drawn from the record.

18. Why This Trial Matters Statistically

This trial illustrates how an endpoint can combine two clinically relevant dimensions: reported rhinoconjunctivitis symptoms and use of rescue medication. A change in a combined score can be informative about overall measured burden, but it also requires readers to understand the construction of the score and to avoid attributing the entire contrast to one component without examining the component outcomes.

The peak-season definition is another important statistical feature. Rather than averaging across an unspecified period, the primary endpoint uses a 15-day window selected by the highest moving pollen average. The resulting estimate is tied to that operational definition. Readers can therefore distinguish a seasonal peak-period comparison from an average over the entire ragweed season, which is separately listed as a secondary outcome.

The record also demonstrates why estimates, intervals, and p-values serve different purposes. The difference gives the direction and scale on the score; the confidence interval describes precision; and the p-value addresses compatibility with a null comparison under the reported test. A small p-value alone does not explain the size, uncertainty, distribution of individual outcomes, or practical importance of the observed contrast.

Finally, the trial highlights the value of separating the sponsor's analysis from simple recalculation. Recalculations from summaries can check direction and approximate magnitude, but the registry's reported model-based analysis remains the principal inferential result. The record's unreported details about multiplicity, missing data, and original design assumptions also show why statistical interpretation requires attention not only to significant findings, but to the analysis plan and the limits of what is documented.

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 endpoint depends on e-diary entries from the participant, parent, or guardian. The analysis population required at least one relevant entry, but the registry entries do not report the amount or pattern of missing diary data, or how missing observations were handled. This limits assessment of whether diary availability could have influenced the analyzed comparison.

The primary score combines symptoms and medication use. Although the registry lists the component outcomes, the combined endpoint alone cannot establish how much each component contributed. The registry also does not report a threshold for a clinically important difference on the score, limiting interpretation of the practical meaning of the estimated contrast.

The testing plan for the primary and secondary outcomes is not reported in the registry record details used. Without a stated multiplicity procedure, the secondary p-values should be interpreted cautiously, especially because several outcomes overlap in content. Numerical results are also unavailable for the listed secondary safety outcomes concerning local reactions, anaphylaxis or systemic allergic reactions, and epinephrine treatment.

The registry identifies ANOVA for the primary comparison and a zero-inflated log-normal model for the peak-season medication-score comparison, but it does not provide all model specifications or diagnostic details. The complete protocol, original sample-size rationale, interim-analysis procedures, and detailed masking roles are not reported in the registry record. These gaps do not invalidate the posted result, but they constrain independent evaluation of design choices and robustness.

The population description is limited to children aged 5 to 17 years with ragweed-induced allergic rhinitis or rhinoconjunctivitis, with or without asthma. Other demographic and clinical details are not reported in the registry record used. The findings should not be assumed to generalize beyond the studied population, endpoint, or season definition without further evidence.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Efficacy and Safety Study of RAGWITEK™ (MK-3641) in Children With Ragweed-Induced Rhinoconjunctivitis With or Without Asthma (MK-3641-008) — NCT02478398.
• Registry record last updated 2019-09-06; status last verified 2019-08.
• Results first posted 2019-07-09.
• 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

NCT02478398 is a completed phase III randomized, placebo-controlled, triple-masked, parallel-group trial of short ragweed pollen allergen extract in children aged 5 to 17 years with ragweed-induced rhinoconjunctivitis, with or without asthma. The registry lists enrollment of 1025, a start date of 2015-07-20, and primary completion on 2018-11-09.

The primary outcome was average Total Combined Score during the 15-day peak ragweed-season period, combining symptom and rescue-medication scores. The sponsor-reported mean difference was -2.73, with a 95% confidence interval from -3.45 to -2.00 and p < 0.001. Lower scores indicate less combined symptom and medication burden.

Related continuous secondary outcomes showed the same broad direction in their posted comparisons. Some secondary safety outcome results, the multiplicity plan, detailed missing-data methods, and the original sample-size justification are not reported in the registry record details used for this analysis.