This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record.
1. Trial at a Glance
LIBERTY ASTHMA QUEST was a randomized, triple-masked, parallel-group phase 3 trial evaluating whether dupilumab, given every two weeks at one of two doses, reduced the rate of severe asthma exacerbations over 52 weeks and improved pre-bronchodilator FEV1 at Week 12 compared with matched placebo, in patients with persistent asthma receiving inhaled corticosteroid therapy.
| Feature | LIBERTY ASTHMA QUEST |
|---|---|
| Official title | Evaluation of Dupilumab in Patients With Persistent Asthma (Liberty Asthma Quest) |
| Phase | Phase 3 |
| Condition | Asthma |
| Design | Randomized, parallel-group, placebo-controlled, triple-masked |
| Arms | 4: dupilumab 200 mg q2w, placebo (for dupilumab 200 mg) q2w, dupilumab 300 mg q2w, placebo (for dupilumab 300 mg) q2w |
| Enrollment | 1902 |
| Primary endpoints | Annualized rate of severe exacerbation events over 52 weeks; absolute change from baseline in pre-bronchodilator FEV1 at Week 12 (both in the ITT population) |
| Primary analysis methods | Negative binomial regression (exacerbations); mixed-effect model with repeated measures, MMRM (FEV1) |
| Error control | Hierarchical (fixed-sequence) testing at the 0.05 level across the primary and key secondary outcome measures |
| Dates | Start 2015-04-27; primary completion 2017-07-29 |
| ClinicalTrials.gov | NCT02414854 |
| Sponsor | Sanofi (industry) |
2. Clinical Question
The trial asked whether adding dupilumab to ongoing inhaled corticosteroid therapy reduces the frequency of severe asthma exacerbations over one year and improves airflow (pre-bronchodilator FEV1) within 12 weeks, relative to placebo. Because two dose levels were tested, each against its own matched placebo, the trial effectively contains two parallel randomized comparisons that share a common analysis model.
Population
Patients with persistent asthma receiving inhaled corticosteroid (ICS) therapy, with albuterol/salbutamol or levalbuterol/levosalbutamol available as reliever medication.
Intervention
Dupilumab 200 mg every two weeks (q2w) or dupilumab 300 mg q2w, added to ICS therapy.
Comparator
Placebo q2w, matched separately to each dupilumab dose (placebo for 200 mg and placebo for 300 mg).
Primary question
Does each dupilumab regimen lower the annualized rate of severe exacerbations over 52 weeks and increase pre-bronchodilator FEV1 at Week 12 compared with its matched placebo?
3. Trial Design
Dupilumab 200 mg q2w vs matched placebo
- Dupilumab 200 mg every two weeks
- Placebo (for dupilumab 200 mg) every two weeks
- Inhaled corticosteroid therapy in both arms
- Albuterol/salbutamol or levalbuterol/levosalbutamol as reliever
Dupilumab 300 mg q2w vs matched placebo
- Dupilumab 300 mg every two weeks
- Placebo (for dupilumab 300 mg) every two weeks
- Inhaled corticosteroid therapy in both arms
- Albuterol/salbutamol or levalbuterol/levosalbutamol as reliever
The numbers of participants at risk in the safety data are roughly twice as large in each dupilumab arm as in its matched placebo arm, consistent with unequal allocation within each dose pair. The registry fields summarized here do not state the allocation ratio explicitly, so the pattern is best read as descriptive.
4. Endpoints
Primary endpoints
| Endpoint (registry wording) | Definition | Time frame |
|---|---|---|
| Annualized Rate of Severe Exacerbation Events During The 52-Week Treatment Period: Intent-to-Treat (ITT) Population | A severe exacerbation was defined as a deterioration of asthma requiring: use of systemic corticosteroids for ≥3 days; or hospitalization or emergency room visit because of asthma, requiring systemic corticosteroids. Annualized event rate was the total number of exacerbations that occurred during the treatment period divided by the total number of participant-years treated. | Baseline to Week 52 |
| Absolute Change From Baseline in Pre-Bronchodilator Forced Expiratory Volume in 1 Second (FEV1) at Week 12: ITT Population | FEV1 was the volume of air exhaled in the first second of a forced expiration as measured by spirometer. | Baseline, Week 12 |
Key secondary endpoints with posted analyses
| Endpoint (registry wording, shortened) | Population | Time frame |
|---|---|---|
| Percent change from baseline in pre-bronchodilator FEV1 at Week 12 | ITT | Baseline, Week 12 |
| Annualized rate of severe exacerbation events during the 52-week treatment period | ITT with baseline eosinophils ≥0.15 Giga/L | Baseline to Week 52 |
| Absolute change from baseline in pre-bronchodilator FEV1 at Week 12 | ITT with baseline eosinophils ≥0.15 Giga/L | Baseline, Week 12 |
| Annualized rate of severe exacerbation events during the 52-week treatment period | ITT with baseline eosinophils ≥0.3 Giga/L | Baseline to Week 52 |
| Absolute change from baseline in pre-bronchodilator FEV1 at Week 12 | ITT with baseline eosinophils ≥0.3 Giga/L | Baseline, Week 12 |
| Annualized rate of severe exacerbation events during the 52-week treatment period | ITT with baseline eosinophils <0.3 Giga/L | Baseline to Week 52 |
The two primary endpoints are statistically very different objects. The exacerbation endpoint is a count of recurrent events accumulated over a year, divided by exposure time; it is skewed, contains many zeros and is sensitive to how long each participant was observed. The FEV1 endpoint is a continuous measurement taken repeatedly at visits up to Week 12 and summarized as a change from baseline. Each requires its own model, which is why the trial used negative binomial regression for one and MMRM for the other.
5. Analysis Populations
| Analysis population | Registry description | Used for |
|---|---|---|
| Intent-to-treat (ITT) | All randomized population analyzed according to the treatment group allocated by randomization | Both primary endpoints; percent change in FEV1 |
| ITT with available data | For FEV1 analyses, "Number analyzed" signifies number of participants with available data for the specified category | MMRM analyses of FEV1 (n=954 for the 300 mg vs placebo percent-change analysis) |
| ITT with baseline eosinophils ≥0.15 Giga/L | ITT participants in this baseline eosinophil category | Secondary exacerbation and FEV1 analyses |
| ITT with baseline eosinophils ≥0.3 Giga/L | ITT participants in this baseline eosinophil category | Secondary exacerbation and FEV1 analyses |
| ITT with baseline eosinophils <0.3 Giga/L | ITT participants in this baseline eosinophil category | Secondary exacerbation analysis |
The eosinophil populations are defined by a baseline measurement, so they are subsets of randomized participants in which the treatment comparison remains randomized. They are, however, not mutually exclusive: everyone with eosinophils ≥0.3 Giga/L is also in the ≥0.15 Giga/L population, and the ≥0.3 and <0.3 populations partition the ITT population. These overlaps matter when reading the results as a set.
6. Primary Results: Severe Exacerbations
Both dupilumab regimens were compared with their matched placebo using a negative binomial model. The registry labels the effect measure "relative risk"; for an event-rate endpoint of this kind it is a rate ratio: the ratio of the model-estimated annualized exacerbation rates.
Dupilumab 300 mg q2w vs placebo (test 1 of the hierarchy)
Rate ratio for severe exacerbations
95% CI: 0.43–0.68 · P < 0.0001 (two-sided CI)
Unit: exacerbations per participant-year · Population: ITT · Hypothesis: superiority
What it means. A rate ratio of 0.54 means that, after adjustment for the model covariates and for differences in observation time, the estimated annualized rate of severe exacerbations with dupilumab 300 mg was 54% of the rate with its matched placebo, a 46% lower estimated rate.
What it does not mean. It does not mean that 46% fewer participants had an exacerbation, or that each individual's risk fell by 46%. A rate ratio compares average event frequencies across groups; a participant with several events contributes more to the rate than one with none. It also says nothing directly about the absolute number of exacerbations avoided, which depends on the placebo-group rate.
Precision. The 95% confidence interval of 0.43 to 0.68 is entirely below 1, and even its upper limit corresponds to a 32% lower estimated rate. The interval describes sampling uncertainty in the population-average ratio under the negative binomial model, not the spread of responses among individuals.
The p-value. P < 0.0001 indicates that data this extreme would be very unlikely if the true rate ratio were 1. It does not measure how large the effect is; that information is in the estimate and its interval.
Cautions. This was the first test in the fixed sequence, so it was performed at the full 0.05 level. Rate ratios from a negative binomial model depend on the assumed variance structure; if overdispersion is poorly captured, the interval may be too narrow or too wide. Participants who stopped early contribute their observed follow-up via the offset, which assumes that their exacerbation rate while observed is representative of the rate they would have had over the full period.
Dupilumab 200 mg q2w vs placebo (test 3 of the hierarchy)
Rate ratio for severe exacerbations
95% CI: 0.413–0.662 · P < 0.0001 (two-sided CI)
Unit: exacerbations per participant-year · Population: ITT · Hypothesis: superiority
What it means. The estimated annualized severe exacerbation rate with dupilumab 200 mg was 52.3% of the rate with its matched placebo, a 47.7% lower estimated rate, under the same adjusted negative binomial model.
What it does not mean. The point estimate for 200 mg (0.523) is numerically slightly lower than for 300 mg (0.54), but this does not show that the lower dose is more effective. The two estimates come from different placebo comparators, and their confidence intervals overlap almost completely. No direct 200 mg versus 300 mg comparison is reported in the registry analyses.
Precision. The interval 0.413 to 0.662 is similar in width to the 300 mg interval, as expected from comparisons of similar size.
The p-value and multiplicity. This test was eligible for confirmatory interpretation only because tests 1 and 2 were both statistically significant. Under the hierarchical procedure the whole sequence shares one 0.05 error budget, so P < 0.0001 here is a confirmatory result, not a nominal one. As before, the p-value reflects the strength of evidence against no difference, not the size of the difference.
7. Primary Results: Pre-Bronchodilator FEV1 at Week 12
The FEV1 endpoint was analysed with an MMRM model, and the effect measure is the least squares (LS) mean difference in absolute change from baseline, in liters, between dupilumab and matched placebo at Week 12.
Dupilumab 300 mg q2w vs placebo (test 2 of the hierarchy)
LS mean difference in change from baseline in FEV1
95% CI: 0.08–0.18 L · P < 0.0001 (two-sided CI)
Population: ITT with available data · Hypothesis: superiority
What it means. After adjustment for baseline FEV1 and the other covariates, the model-estimated mean improvement in pre-bronchodilator FEV1 from baseline to Week 12 was 0.13 L greater with dupilumab 300 mg than with its matched placebo.
What it does not mean. This is a difference between group means in the change from baseline. It is not the average improvement within the dupilumab arm (placebo participants may also have changed), and it does not imply that every treated participant gained 0.13 L. It is also a Week 12 estimate; it does not by itself describe lung function at Week 52.
Precision. The 95% CI of 0.08 to 0.18 L excludes zero and indicates that the data are compatible with differences between 0.08 L and 0.18 L. Whether the lower end is clinically meaningful is a clinical judgment, not a statistical one.
The p-value. P < 0.0001 says the difference is unlikely to be zero; it does not grade its clinical importance.
Cautions. The analysis used participants with available data and an MMRM framework, which handles intermittent or dropout-related missing visits validly if data are missing at random given the observed data and covariates. If participants with poorer lung function were more likely to miss visits for reasons not captured by the model, the estimate could be biased. This was test 2 in the sequence, performed after test 1 was significant.
Dupilumab 200 mg q2w vs placebo (test 4 of the hierarchy)
LS mean difference in change from baseline in FEV1
95% CI: 0.08–0.19 L · P < 0.0001 (two-sided CI)
Population: ITT with available data · Hypothesis: superiority
What it means. The estimated adjusted mean improvement in pre-bronchodilator FEV1 at Week 12 was 0.14 L greater with dupilumab 200 mg than with its matched placebo.
What it does not mean. The similarity of 0.14 L and 0.13 L across doses is not evidence of equivalence between doses; the trial did not test doses against each other, and each estimate has its own placebo reference.
Precision. The interval of 0.08 to 0.19 L is nearly identical to that for 300 mg, reflecting similar sample sizes and variability.
The p-value and multiplicity. As test 4, this comparison could be claimed as confirmatory only because tests 1 to 3 had all succeeded. The p-value is again a statement about compatibility with no difference, not about magnitude. The same missing-at-random caution applies as for the 300 mg comparison.
| Primary endpoint | Comparison | Method | Estimate (95% CI) | P-value | Test no. |
|---|---|---|---|---|---|
| Severe exacerbation rate, 52 weeks | 300 mg vs placebo | Negative binomial | Rate ratio 0.54 (0.43–0.68) | <0.0001 | 1 |
| Pre-BD FEV1 change, Week 12 | 300 mg vs placebo | MMRM | LS mean diff 0.13 L (0.08–0.18) | <0.0001 | 2 |
| Severe exacerbation rate, 52 weeks | 200 mg vs placebo | Negative binomial | Rate ratio 0.523 (0.413–0.662) | <0.0001 | 3 |
| Pre-BD FEV1 change, Week 12 | 200 mg vs placebo | MMRM | LS mean diff 0.14 L (0.08–0.19) | <0.0001 | 4 |
8. Secondary Results
The posted secondary analyses compare dupilumab 300 mg q2w with its matched placebo. They continue the same hierarchical sequence, so each result carries confirmatory weight only if every earlier test in the sequence was significant.
| Test no. | Endpoint | Population | Estimate (95% CI) | P-value |
|---|---|---|---|---|
| 5 | Percent change in pre-BD FEV1, Week 12 (MMRM, n=954) | ITT | LS mean diff 9.41 (5.74–13.07) percentage points | <0.0001 |
| 6 | Severe exacerbation rate, 52 weeks (negative binomial) | Eosinophils ≥0.15 Giga/L | Rate ratio 0.402 (0.307–0.526) | <0.0001 |
| 7 | Absolute change in pre-BD FEV1, Week 12 (MMRM) | Eosinophils ≥0.15 Giga/L | LS mean diff 0.15 L (0.09–0.21) | <0.0001 |
| 8 | Severe exacerbation rate, 52 weeks (negative binomial) | Eosinophils ≥0.3 Giga/L | Rate ratio 0.326 (0.234–0.454) | <0.0001 |
| 9 | Absolute change in pre-BD FEV1, Week 12 (MMRM) | Eosinophils ≥0.3 Giga/L | LS mean diff 0.24 L (0.16–0.32) | <0.0001 |
| 10 | Severe exacerbation rate, 52 weeks (negative binomial) | Eosinophils <0.3 Giga/L | Rate ratio 0.834 (0.608–1.144) | 0.2599 |
Reading the eosinophil gradient
The rate ratios form a clear ordering: 0.326 in the ≥0.3 Giga/L population (a 67.4% lower estimated rate), 0.402 in the ≥0.15 Giga/L population (59.8% lower), 0.54 overall (46% lower) and 0.834 in the <0.3 Giga/L population (16.6% lower). FEV1 differences follow the same direction, from 0.13 L overall to 0.15 L at ≥0.15 Giga/L and 0.24 L at ≥0.3 Giga/L.
In the <0.3 Giga/L population the interval of 0.608 to 1.144 includes 1, and P = 0.2599. This does not show that dupilumab has no effect in that group: the interval is compatible with a moderate reduction as well as a small increase. It shows that the data in this subset do not establish a difference from placebo.
Percent change in FEV1
The percent-change analysis (test 5) estimated a 9.41 percentage-point greater improvement with 300 mg than placebo (95% CI 5.74 to 13.07). Percent change and absolute change carry similar information, but percent change scales each participant's improvement by their own baseline, which gives more weight to improvements in participants with lower baseline FEV1. Because the model also adjusts for baseline FEV1, the two analyses answer closely related questions and would be expected to agree in direction, as they do here.
9. Safety: Serious Adverse Events
The registry reports serious adverse events as participants affected out of participants at risk in each arm. No formal between-arm statistical comparison of serious adverse events is posted.
| Arm | Participants with serious adverse events / at risk |
|---|---|
| Placebo (for dupilumab 200 mg) q2w | 26 / 313 |
| Dupilumab 200 mg q2w | 51 / 631 |
| Placebo (for dupilumab 300 mg) q2w | 28 / 321 |
| Dupilumab 300 mg q2w | 56 / 632 |
Because the dupilumab arms have about twice as many participants at risk as their placebo arms, raw counts should not be compared directly; the counts must be read relative to their denominators. Serious adverse events are a heterogeneous category of events of different types and causes, so an overall proportion is a screening summary, not an estimate of a specific drug-related risk. A risk ratio with a confidence interval would be the natural summary for a formal comparison of proportions, but interpreting such a comparison would need to account for the many safety categories typically examined without multiplicity control.
10. Statistical Methodology
Negative binomial regression for exacerbation rates
The exacerbation analysis used the total number of events with onset from randomization up to Week 52 or the last contact date, whichever came earlier, as the response. The model included the four treatment groups, age, region, baseline eosinophil strata, baseline ICS dose level and the number of severe exacerbation events within 1 year prior to the study as covariates, with the log-transformed standardized observation duration as an offset.
Here Yi is the number of severe exacerbations, ti the standardized observation time, and k the dispersion parameter. The rate ratio is exp(βtrt) for a given dupilumab arm relative to its matched placebo.
The offset converts counts into rates: a participant observed for half a year with one exacerbation is treated differently from one observed for a full year with one exacerbation. The dispersion term k allows the variance to exceed the mean, which is typical of exacerbation data because a minority of participants experience several events while many have none. A Poisson model would ignore this extra variation and produce intervals that are too narrow.
Mixed-effect model with repeated measures (MMRM) for FEV1
The FEV1 analysis used the change from baseline in FEV1 values up to Week 12 as the response, with treatment, age, sex, baseline height, region, baseline eosinophil strata, baseline ICS dose level, visit, treatment-by-visit interaction, baseline FEV1 and baseline-by-visit interaction as covariates.
The residuals εij for the same participant are allowed to be correlated across visits. The treatment effect at Week 12 is the difference in LS means for the treatment-by-visit combination at that visit.
The treatment-by-visit interaction lets the treatment effect differ at each visit, so the Week 12 estimate is not forced to equal an average over visits. Height, age and sex are natural covariates for FEV1 because they are major determinants of lung volume; adjusting for them and for baseline FEV1 reduces residual variability and narrows the confidence interval without introducing bias in a randomized comparison.
Intention-to-treat principle
The primary analyses were performed in the ITT population, including all randomized participants analysed according to the treatment group allocated by randomization. This preserves the comparability created by randomization. In the FEV1 analyses, participants contribute to the MMRM according to the visits at which they have data, so the practical population is ITT participants with available data.
Missing data
The two endpoints handle incomplete follow-up differently. In the exacerbation model, events are counted up to Week 52 or the last contact date, and the offset adjusts for shorter observation. In the FEV1 model, MMRM uses all observed visits and yields valid estimates under a missing-at-random assumption. Neither approach protects against missingness that depends on unobserved outcomes, and sensitivity analyses for alternative missing-data assumptions are not among the analyses posted to the registry.
11. Multiplicity and the Hierarchical Testing Procedure
The registry states that a hierarchical testing procedure was used to control the type I error rate at the 0.05 level. The procedure included the 2 primary outcome measures and the first 13 secondary outcome measures, and considered 2 pair-wise comparisons: dupilumab 200 mg q2w versus its placebo and dupilumab 300 mg q2w versus its placebo.
| Order | Comparison | Endpoint / population | Result |
|---|---|---|---|
| 1 | 300 mg vs placebo | Severe exacerbation rate, ITT | Significant; continue |
| 2 | 300 mg vs placebo | FEV1 absolute change, ITT | Significant; continue |
| 3 | 200 mg vs placebo | Severe exacerbation rate, ITT | Significant; continue |
| 4 | 200 mg vs placebo | FEV1 absolute change, ITT | Significant; continue |
| 5 | 300 mg vs placebo | FEV1 percent change, ITT | Significant; continue |
| 6 | 300 mg vs placebo | Severe exacerbation rate, eosinophils ≥0.15 Giga/L | Significant; continue |
| 7 | 300 mg vs placebo | FEV1 absolute change, eosinophils ≥0.15 Giga/L | Significant; continue |
| 8 | 300 mg vs placebo | Severe exacerbation rate, eosinophils ≥0.3 Giga/L | Significant; continue |
| 9 | 300 mg vs placebo | FEV1 absolute change, eosinophils ≥0.3 Giga/L | Significant; continue |
| 10 | 300 mg vs placebo | Severe exacerbation rate, eosinophils <0.3 Giga/L | Not significant (P = 0.2599); sequence stops |
Why a fixed sequence works
Each hypothesis is tested at the full 0.05 level, but only if every earlier hypothesis was rejected. Because a false positive can only enter the chain through the first false null hypothesis encountered, the familywise error rate stays at 0.05 without splitting alpha.
The price of the ordering
Power is concentrated on early hypotheses. A failure anywhere ends confirmatory testing for everything below it, even for outcomes that would have been highly significant on their own.
Why 300 mg came first
Placing the 300 mg comparisons at positions 1 and 2 gave the higher dose the first claim on alpha. The 200 mg comparisons were reached only after both 300 mg primary tests succeeded.
Subgroups inside the hierarchy
Unusually, the eosinophil populations were placed inside the confirmatory sequence, so tests 6 to 9 are controlled confirmatory findings rather than exploratory subgroup results.
12. Statistical Methods Explained
Why was a negative binomial model used instead of comparing proportions?
The endpoint is a rate of recurrent events, not a yes/no outcome. Comparing the proportion of participants with at least one exacerbation would discard information from participants with multiple events and ignore differences in follow-up time. The negative binomial model uses every event, accounts for variable observation time through the offset, and allows for the overdispersion that is characteristic of exacerbation counts.
The registry calls 0.54 a "relative risk". Is that the right term?
In this context it is a ratio of event rates (exacerbations per participant-year), usually called a rate ratio. It is interpreted like a relative risk, as a multiplicative comparison with 1 meaning no difference, but it applies to event frequency rather than to the probability of having any event. A 0.54 rate ratio does not translate into 46% fewer participants experiencing an exacerbation.
Why use MMRM for a Week 12 endpoint rather than a simple analysis of covariance at Week 12?
MMRM uses FEV1 measurements from all visits up to Week 12 and models their correlation within participants. A participant missing the Week 12 visit still contributes information through earlier visits, and under a missing-at-random assumption the Week 12 estimate remains valid. An ANCOVA at Week 12 alone would drop such participants or require imputation.
What does an LS mean difference of 0.13 L represent?
It is the difference between the model-adjusted mean changes from baseline in the two groups at Week 12, estimated at common covariate values. "Least squares" refers to the model-based averaging, which removes chance imbalances in covariates such as baseline FEV1 and height. It is an average group-level contrast, not an individual response.
Why is test 3 (200 mg exacerbations) confirmatory even though it came after two other tests?
In a fixed-sequence procedure, alpha is not divided among hypotheses. Each test uses the full 0.05 level, conditional on all preceding tests having been significant. Since tests 1 and 2 succeeded, test 3 was performed at 0.05 with the familywise error rate still controlled.
Does the nonsignificant result in eosinophils <0.3 Giga/L mean dupilumab does not work in that group?
No. The rate ratio of 0.834 with interval 0.608 to 1.144 is compatible both with a meaningful reduction and with no reduction. Absence of statistical significance is not evidence of absence of effect. The result also halted the hierarchy, which limits what can be claimed for any later outcome measures in the prespecified order.
Why were all four treatment groups in the same model?
Fitting one model to all arms estimates covariate effects and the dispersion (or residual covariance) from the full trial, which improves precision. The dose-specific contrasts, such as 300 mg versus its placebo, are then extracted from that common model.
13. Limitations
- Relative, not absolute, effects: the exacerbation results are reported as rate ratios. The absolute number of exacerbations avoided per participant-year depends on the placebo event rate, and the rate ratio alone cannot convey it.
- Dose-specific placebo comparisons: each dose is compared with its own placebo, so the 200 mg and 300 mg estimates are not a direct dose comparison.
- Subgroup heterogeneity: the eosinophil gradient is consistent and prespecified, but no treatment-by-eosinophil interaction test is posted in the registry.
- Overlapping populations: the ≥0.15 and ≥0.3 Giga/L results share many participants and are not independent confirmations of each other.
- Missing data assumptions: MMRM and the offset-based negative binomial model rely on missing-at-random or representative-follow-up assumptions.
- Model dependence: rate ratios depend on the negative binomial variance assumption; LS mean differences depend on the MMRM covariance structure and covariate set.
- Hierarchy cut-off: the nonsignificant test 10 ends confirmatory claims for later outcome measures in the prespecified sequence.
- Time horizon: FEV1 was a Week 12 primary endpoint and exacerbations were counted over 52 weeks; neither addresses longer-term outcomes.
- Safety summaries: serious adverse events are reported as counts without a formal comparison, and they aggregate diverse event types.
14. Why This Trial Matters Statistically
LIBERTY ASTHMA QUEST is a strong teaching case because it combines two very different primary endpoint types, two dose-specific comparisons and a long fixed-sequence hierarchy that includes biomarker-defined populations, and because that hierarchy actually stopped partway through.
| Concept | How it appears in LIBERTY ASTHMA QUEST |
|---|---|
| Count data and overdispersion | Severe exacerbations modelled by negative binomial regression |
| Offsets and exposure time | Log-transformed standardized observation duration converts counts to annualized rates |
| Rate ratio | 0.54 (300 mg) and 0.523 (200 mg) versus matched placebo |
| Repeated measures | MMRM for FEV1 change up to Week 12 with treatment-by-visit interaction |
| Covariate adjustment | Baseline FEV1, height, age, sex, region, eosinophil strata, ICS dose, prior exacerbations |
| Intention-to-treat | All randomized participants analysed as allocated |
| Multiplicity | Hierarchical testing at 0.05 across primary and key secondary outcome measures for two dose comparisons |
| Biomarker-defined populations | Eosinophil ≥0.15, ≥0.3 and <0.3 Giga/L analyses within the hierarchy |
| Non-significance and error control | Test 10 (P = 0.2599) stops the confirmatory sequence |
| Multi-arm placebo design | Separate matched placebo for each dose within a single analysis model |
15. Related Tutorials
Learn more about the methods used in this trial:
16. Related Calculators
17. Sources
- ClinicalTrials.gov: NCT02414854: Evaluation of Dupilumab in Patients With Persistent Asthma (Liberty Asthma Quest).
- PubMed: PMID 29782217.
- PubMed: PMID 42178021.
- PubMed: PMID 40767333.
- PubMed: PMID 40458676.
- PubMed: PMID 39424189.
Explore more trial statistics
Follow the methods used in this trial into deeper tutorials, then try them out with an appropriate calculator.
18. Record Summary
LIBERTY ASTHMA QUEST compared two dupilumab doses with matched placebo in 1902 enrolled participants with persistent asthma. Both doses produced severe exacerbation rate ratios below 1 (0.54 and 0.523) and Week 12 FEV1 improvements over placebo (0.13 L and 0.14 L), all significant within a hierarchical procedure controlling the type I error rate at 0.05. Secondary analyses for 300 mg showed larger estimated effects in higher-eosinophil populations and a nonsignificant exacerbation result below 0.3 Giga/L, where the testing sequence stopped. The most useful reading combines rate ratios, adjusted mean differences, their confidence intervals and the structure of the testing hierarchy.