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
FLAME was a randomized, parallel-group, triple-masked phase 3 study in chronic obstructive pulmonary disease (COPD), comparing QVA149 with a long acting B2 agonist (LABA) and inhaled corticosteroid (ICS). The registry reports a total enrollment of 3362 patients and a 52-week primary endpoint focused on the rate of COPD exacerbations.
| Feature | FLAME |
|---|---|
| Trial name | FLAME |
| Brief title | QVA vs. Salmeterol/Fluticasone, 52-week Exacerbation Study, FLAME (EFfect of Indacaterol Glycopyronium Vs Fluticasone Salmeterol on COPD Exacerbations) |
| Phase | Phase 3 |
| Status | Completed |
| Therapeutic area | Pulmonology |
| Condition | Chronic Obstructive Pulmonary Disease (COPD) |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Primary purpose | Treatment |
| Enrollment | 3362 |
| Lead sponsor | Novartis Pharmaceuticals |
| Sponsor type | Industry |
| Start | 2013-07 |
| Primary completion | 2015-09 |
| ClinicalTrials.gov | NCT01782326 |
2. Clinical Question
The central statistical question was whether QVA149 could be shown to be non-inferior to a long acting B2 agonist and inhaled corticosteroid combination for the rate of COPD exacerbations over 52 weeks, and, if non-inferiority was established, whether the same analysis could support a claim of superiority for reducing exacerbation rate.
Population
Patients with chronic obstructive pulmonary disease enrolled in a phase 3 randomized treatment study. The ClinicalTrials.gov record does not provide a complete baseline-characteristic table.
Intervention
QVA149, identified in the registry as a drug intervention.
Comparator
Long acting B2 agonist (LABA) and inhaled corticosteroid (ICS), identified in the registry as a drug intervention.
Primary question
Is the COPD exacerbation rate with QVA149 no more than the prespecified non-inferiority margin above the comparator rate, and, conditional on non-inferiority, is QVA149 superior?
3. Trial Design
QVA149
- Drug intervention
- Compared with a long acting B2 agonist and inhaled corticosteroid
- Primary outcome assessed over 52 weeks
Long acting B2 agonist and inhaled corticosteroid
- Drug intervention
- Comparator for QVA149
- Primary outcome assessed over 52 weeks
4. Endpoints
The registry reports one primary endpoint and multiple secondary endpoints with formal statistical analyses. The primary endpoint is an event-rate measure rather than a conventional binary endpoint, while several secondary endpoints use time-to-event methods.
| Endpoint | Time frame | Analysis / effect measure |
|---|---|---|
| Rate of COPD Exacerbations | 52 weeks | Generalized linear model assuming a negative binomial distribution; rate ratio |
| Time to First COPD Exacerbation. | 52 weeks | Cox proportional-hazards model; hazard ratio |
| Rate of Moderate to Severe COPD Exacerbations. | 52 weeks | Generalized linear model; rate ratio |
| Time to First Moderate to Severe COPD Exacerbation. | 52 weeks. | Cox proportional-hazards model; hazard ratio |
| Time to First Moderate to Severe COPD Exacerbations Requiring Treatment With Systemic Corticosteroids | 52 weeks | Cox proportional-hazards model; hazard ratio |
| Time to First Moderate to Severe COPD Exacerbations Requiring Treatment With Antibiotics | 52 weeks | Cox proportional-hazards model; hazard ratio |
| Time to First Moderate to Severe COPD Exacerbations Requiring Hospitalization | 52 weeks | Cox proportional-hazards model; hazard ratio |
| Time to First Moderate to Severe COPD Exacerbations Requiring Re-hospitalization Within 30 Days | 52 weeks | Cox proportional-hazards model; hazard ratio |
Primary endpoint definition
The registry definition specifies that COPD exacerbations starting between first dose and one day after last treatment are included. COPD exacerbations that occurred within 7 days of each other are collapsed as one event. Estimates are from a generalized linear model assuming a negative binomial distribution, with terms for treatment, baseline total symptom score, and baseline COPD exacerbation history.
5. Statistical Methodology
Generalized linear model with a negative binomial distribution
The primary exacerbation-rate analysis used a generalized linear model assuming a negative binomial distribution. This is appropriate to the structure of recurrent event counts when variability can exceed what a simple Poisson model would accommodate.
A rate ratio below 1 indicates a lower estimated exacerbation rate in the QVA149 group relative to the comparator. The reported model also incorporated baseline total symptom score and baseline COPD exacerbation history.
Per-protocol analysis for the primary endpoint
The posted primary analysis was conducted in the per-protocol set (PPS). The registry defines the PPS as all patients in the full analysis set without any major protocol deviations, with only PPS patients having non-missing values for all terms in the negative binomial model included in the analysis.
This is particularly important because the trial was designed around a non-inferiority question. A per-protocol analysis can provide information about treatment performance under adherence to the protocol, while the exact relationship between the PPS and other analysis populations must be kept explicit rather than treating all analyses as interchangeable.
Cox proportional-hazards model
The secondary time-to-event analyses used Cox proportional-hazards models. These models estimate a relative hazard for experiencing the first specified event, allowing patients who have not experienced the event during available follow-up to contribute information through their censoring time.
The hazard ratio describes a relative model-based event rate over time. It is not a rate ratio for recurrent exacerbations and is not an absolute risk difference.
Full analysis set and missing values
The secondary analyses identify the full analysis set (FAS) as including randomized patients who received at least one dose of study drug and had no major GCP violations. The posted analyses also reference non-missing values for all model terms and identify multiple imputation / missing data as an analysis concept.
Non-inferiority followed by superiority
The primary endpoint was evaluated under a two-stage inferential logic. The study was designed to have >95% power to rule out a 1.15-fold increase in the rate of exacerbations for QVA149 versus salmeterol/fluticasone. The registry states that if the upper limit of the confidence interval was <1.15, non-inferiority could be claimed. If non-inferiority was demonstrated, superiority could be claimed if the upper limit of the same confidence interval was <1.
Non-inferiority threshold
The relevant boundary was 1.15. The question was whether the observed uncertainty interval excluded a QVA149 exacerbation rate more than 1.15 times the comparator rate.
Superiority threshold
After non-inferiority, the same two-sided confidence interval was assessed against 1. A rate ratio below 1 with an upper confidence limit below 1 supports superiority under the posted analysis rule.
6. Results: Primary Endpoint
The registry posts two formal analyses for the primary endpoint, reflecting the prespecified non-inferiority and superiority framework. Both use the same estimated rate ratio and 95% two-sided confidence interval.
Rate of COPD Exacerbations — Non-inferiority Analysis
Rate ratio for COPD exacerbations
95% CI: 0.83–0.96 · Two-sided CI
Non-inferiority margin: 1.15-fold increase
The upper confidence limit of 0.96 is below the prespecified non-inferiority boundary of 1.15. According to the registry's stated analysis rule, this satisfies the criterion for non-inferiority of QVA149 compared with the LABA/ICS comparator.
The estimated rate ratio of 0.89 means that the modeled COPD exacerbation rate for QVA149 was estimated at 89% of the corresponding comparator rate over the 52-week analysis period. Put another way, the point estimate corresponds to a 11% lower estimated exacerbation rate.
That interpretation is about the estimated rate, not about 11% of patients avoiding an exacerbation and not about an 11% absolute reduction in individual patient risk.
The 95% confidence interval of 0.83–0.96 describes uncertainty around the estimated rate ratio under the statistical model. It does not describe the range of individual patient responses.
No p-value is posted for this non-inferiority analysis. For non-inferiority, the prespecified margin and the confidence interval are central to the decision rule; simply asking whether a conventional null-hypothesis p-value is below a threshold is not the same as applying the stated non-inferiority criterion.
The analysis is based on the PPS and includes only patients with non-missing values for all terms in the negative binomial model. That analysis-population restriction is therefore part of the interpretation of the estimate.
Rate of COPD Exacerbations — Superiority Analysis
Rate ratio for COPD exacerbations
95% CI: 0.83–0.96 · P = 0.003
Superiority analysis after non-inferiority
The upper confidence limit of 0.96 is also below 1, and the posted superiority analysis reports P = 0.003. Under the registry's stated sequence, superiority of QVA149 compared with the LABA/ICS comparator for reducing exacerbation rate could therefore be claimed after non-inferiority was demonstrated.
The estimate remains a rate ratio of 0.89; the superiority analysis does not turn it into a different effect measure. The point estimate still represents the modeled relative exacerbation rate between the two treatment groups.
The confidence interval of 0.83–0.96 is entirely below 1, indicating that the values supported by the interval under the model are below equal rates. It is also entirely below the non-inferiority margin of 1.15.
The p-value of 0.003 is evidence against the null hypothesis used for the posted superiority comparison. It does not measure the size of the treatment effect. The effect size is described by the rate ratio, while the confidence interval describes its precision.
The result should be understood in the context of the prespecified non-inferiority-then-superiority framework rather than as an isolated p-value. The primary analysis is also explicitly a PPS analysis with model-term completeness requirements.
| Primary analysis | Estimate | 95% CI | P-value | Hypothesis |
|---|---|---|---|---|
| Rate of COPD Exacerbations | 0.89 | 0.83–0.96 | Not posted | Non-inferiority |
| Rate of COPD Exacerbations | 0.89 | 0.83–0.96 | 0.003 | Superiority |
7. Results: Secondary Endpoints
The registry posts seven secondary statistical analyses. Five are time-to-event analyses involving the Cox proportional-hazards model, while one is a recurrent exacerbation-rate analysis using a generalized linear model and one additional time-to-event analysis evaluates first exacerbation.
Time to First COPD Exacerbation
Hazard ratio
95% CI: 0.78–0.91 · P < 0.001
52 weeks · Cox proportional-hazards model
The hazard ratio of 0.84 corresponds to an estimated instantaneous hazard of first COPD exacerbation that was approximately 16% lower with QVA149 than with the comparator, under the fitted Cox model.
This is a time-to-first-event estimand. It should not be interpreted as a 16% reduction in the number of exacerbations, because a patient can contribute more than one exacerbation to a recurrent-event rate endpoint while the time-to-first analysis stops at the first event.
The 95% CI of 0.78–0.91 quantifies uncertainty around the hazard-ratio estimate. The p-value of <0.001 addresses the statistical comparison and does not quantify effect magnitude.
As with other Cox analyses, the hazard ratio is model-based. Its interpretation relies on the proportional-hazards framework being a reasonable description of the relative hazards over the relevant follow-up.
Rate of Moderate to Severe COPD Exacerbations
Rate ratio
95% CI: 0.75–0.91 · P < 0.001
52 weeks · Generalized linear model
The rate ratio of 0.83 means that the estimated rate of moderate to severe COPD exacerbations was 83% of the comparator rate under the posted model, corresponding to a 17% lower estimated rate.
The 95% CI of 0.75–0.91 provides the uncertainty interval for this relative rate estimate. It remains below 1 throughout the interval.
The p-value of <0.001 indicates strong statistical evidence against the null comparison used for this superiority analysis. It does not mean that the probability of the observed treatment effect being due to chance is <0.001, nor does it describe the clinical magnitude of the effect.
Time to First Moderate to Severe COPD Exacerbation
Hazard ratio
95% CI: 0.70–0.86 · P < 0.001
52 weeks · Cox proportional-hazards model
The estimated hazard ratio of 0.78 corresponds to a 22% lower estimated instantaneous hazard of a first moderate to severe COPD exacerbation with QVA149 under the Cox model.
The 95% CI of 0.70–0.86 indicates relatively tight statistical uncertainty around the point estimate. It does not imply that every patient experienced the same relative reduction.
The p-value of <0.001 is a measure of evidence against the statistical null hypothesis, not a measure of effect size. The hazard ratio and confidence interval provide the magnitude and precision information.
Time to First Moderate to Severe COPD Exacerbation Requiring Systemic Corticosteroids
Hazard ratio
95% CI: 0.74–1.08 · P = 0.256
52 weeks · Cox proportional-hazards model
The point estimate of 0.90 corresponds to an estimated 10% lower instantaneous hazard of the specified event with QVA149 under the Cox model.
However, the 95% CI of 0.74–1.08 includes 1. This means the interval includes values compatible with either a lower or higher hazard under the model. The p-value of 0.256 does not provide conventional statistical evidence against a null hazard ratio of 1 for this superiority comparison.
This result illustrates why the point estimate alone is insufficient. A hazard ratio below 1 does not automatically establish superiority; the uncertainty interval and prespecified inferential framework also matter.
Time to First Moderate to Severe COPD Exacerbation Requiring Antibiotics
Hazard ratio
95% CI: 0.69–0.95 · P = 0.008
52 weeks · Cox proportional-hazards model
The hazard ratio of 0.81 corresponds to a 19% lower estimated instantaneous hazard of the specified first event with QVA149 under the fitted Cox model.
The 95% CI of 0.69–0.95 remains below 1, while the p-value of 0.008 provides evidence against the null comparison used in this superiority analysis.
The confidence interval is important because it communicates the precision of the estimate; the p-value alone cannot tell the reader whether the estimated effect is large or small.
Time to First Moderate to Severe COPD Exacerbation Requiring Hospitalization
Hazard ratio
95% CI: 0.66–1.00 · P = 0.046
52 weeks · Cox proportional-hazards model
The hazard ratio of 0.81 corresponds to a 19% lower estimated instantaneous hazard of the specified first hospitalization-related event with QVA149 under the Cox model.
The upper confidence limit is 1.00. Thus, the interval reaches the null value rather than lying strictly below it. The posted p-value is 0.046, which is below 0.05, but this should not be converted into a claim that the effect is large or that statistical significance establishes a particular clinical magnitude.
The relatively broad interval also illustrates the additional uncertainty that can arise for a more specific time-to-event outcome compared with the broader exacerbation endpoint.
Time to First Moderate to Severe COPD Exacerbation Requiring Re-hospitalization Within 30 Days
Hazard ratio
95% CI: 0.38–2.10 · P = 0.790
52 weeks · Cox proportional-hazards model
The point estimate of 0.89 corresponds to an estimated 11% lower instantaneous hazard under the Cox model. But the 95% CI of 0.38–2.10 is very wide and includes both substantially lower and substantially higher hazards.
The p-value of 0.790 does not provide evidence against the null comparison. More importantly, the wide confidence interval shows that the point estimate is imprecise for this specific endpoint.
This is a useful statistical distinction: a non-significant result does not prove that the two hazards are identical. The confidence interval shows the range of effect sizes that remain compatible with the observed analysis under its assumptions.
| Secondary endpoint | Effect | 95% CI | P-value |
|---|---|---|---|
| Time to First COPD Exacerbation. | HR 0.84 | 0.78–0.91 | <0.001 |
| Rate of Moderate to Severe COPD Exacerbations. | Rate ratio 0.83 | 0.75–0.91 | <0.001 |
| Time to First Moderate to Severe COPD Exacerbation. | HR 0.78 | 0.70–0.86 | <0.001 |
| Time to first moderate to severe exacerbation requiring systemic corticosteroids | HR 0.90 | 0.74–1.08 | 0.256 |
| Time to first moderate to severe exacerbation requiring antibiotics | HR 0.81 | 0.69–0.95 | 0.008 |
| Time to first moderate to severe exacerbation requiring hospitalization | HR 0.81 | 0.66–1.00 | 0.046 |
| Time to first moderate to severe exacerbation requiring re-hospitalization within 30 days | HR 0.89 | 0.38–2.10 | 0.790 |
8. Safety Results
The ClinicalTrials.gov record reports serious adverse events by randomized arm as affected patients divided by patients at risk. These are the safety figures available for this page.
| Safety measure | QVA149 | LABA + ICS |
|---|---|---|
| Serious adverse events | 308 / 1678 | 334 / 1680 |
QVA149
Serious adverse events affected 308 of 1678 patients at risk in the ClinicalTrials.gov record.
LABA + ICS
Serious adverse events affected 334 of 1680 patients at risk in the ClinicalTrials.gov record.
The serious-adverse-event figures are descriptive counts with denominators as reported in the registry by the registry. The available trial data do not provide a formal statistical comparison, confidence interval, or p-value for this safety measure, so none is added here.
9. Statistical Methods Explained
Why was a negative binomial generalized linear model used?
The primary endpoint counts COPD exacerbations over a 52-week period. A negative binomial model is a generalized linear modeling approach suited to count-rate outcomes when the variability in counts can be greater than the simple Poisson assumption permits. The registry explicitly identifies this distributional assumption for the primary analysis.
What does a rate ratio of 0.89 mean?
A rate ratio of 0.89 means that the estimated exacerbation rate under QVA149 was 0.89 times the comparator rate in the posted model. The point estimate therefore corresponds to a 11% lower estimated rate. It does not mean that 11% of patients benefited or that each patient had exactly an 11% reduction in risk.
Why is the non-inferiority margin important?
The study was designed to rule out a 1.15-fold increase in the exacerbation rate. That margin defines what degree of worsening would still be considered compatible with non-inferiority under the trial's statistical framework. Because the upper 95% confidence limit was 0.96, it was below 1.15.
Why could superiority be tested after non-inferiority?
The registry explicitly states a sequential rule: first establish non-inferiority using the 1.15 boundary, then assess superiority using the same confidence interval against 1. The posted analysis has an upper limit of 0.96, which is below 1, and reports P = 0.003 for superiority.
Why are both rate ratios and hazard ratios reported?
They answer different questions. The rate ratio compares the modeled rate of exacerbations over the study period, whereas the hazard ratio compares the instantaneous rate of experiencing a specified first event over time. A recurrent exacerbation-rate endpoint can count multiple events; a time-to-first endpoint focuses on when the first event occurs.
Why does the analysis population matter?
The primary endpoint was analyzed in the per-protocol set, whereas the posted secondary analyses identify the full analysis set. Non-inferiority trials often pay particular attention to protocol adherence because substantial deviations can complicate interpretation of whether the tested treatment strategy was actually delivered as intended.
What does a p-value not tell us?
A p-value describes the evidence against a specified null hypothesis under the statistical model and testing framework. It does not measure treatment-effect magnitude, does not give the probability that the null hypothesis is true, and does not describe the range of plausible effects. Those questions are addressed more directly by the effect estimate and confidence interval.
10. Non-Inferiority Logic in FLAME
The primary endpoint provides a useful example of why non-inferiority trials require a different reading strategy from a conventional superiority trial.
| Step | Registry criterion | FLAME result |
|---|---|---|
| 1. Define the margin | Rule out a 1.15-fold increase in exacerbation rate | Prespecified margin = 1.15 |
| 2. Estimate treatment effect | Rate ratio with 95% two-sided CI | 0.89 |
| 3. Examine upper confidence limit | Upper limit must be <1.15 for non-inferiority | 0.96 < 1.15 |
| 4. Test superiority if non-inferiority is demonstrated | Upper limit of same CI must be <1 | 0.96 < 1 |
| 5. Review superiority evidence | Formal superiority analysis | P = 0.003 |
The non-inferiority conclusion is not based on the point estimate being below 1 alone. The crucial comparison is between the upper confidence limit and the prespecified margin. A point estimate of 0.89 would not, by itself, establish non-inferiority if the uncertainty interval extended beyond 1.15.
Here, the entire posted 95% confidence interval, 0.83–0.96, lies below both the non-inferiority boundary of 1.15 and the equality boundary of 1.
11. Missing Data and Analysis Populations
The registry data explicitly identify missing-data considerations in the posted analyses. For the primary negative-binomial analysis, only PPS patients with non-missing values for all terms in the model are included. The secondary analyses similarly specify inclusion of patients with non-missing values for all relevant model terms and identify multiple imputation / missing data as an analysis concept.
Primary analysis
The PPS included patients in the FAS without major protocol deviations, with the primary model restricted to patients having non-missing values for all model terms.
Secondary analyses
The posted secondary analyses identify the FAS and reference intention-to-treat analysis and multiple imputation / missing data concepts.
12. Cox Proportional-Hazards Interpretation
Several FLAME secondary endpoints are time-to-event outcomes. The Cox model expresses the treatment comparison as a hazard ratio, making it possible to use the timing of first events rather than reducing follow-up to a simple yes/no endpoint.
Both estimates are below 1, but they refer to different event definitions and therefore should not be treated as interchangeable estimates of one endpoint.
A Cox hazard ratio also depends on the proportional-hazards framework. If the relative hazard changes materially over time, a single HR can compress a more complicated time-varying pattern into one summary measure. The ClinicalTrials.gov record does not report a formal test or diagnostic for the proportional-hazards assumption, so no such conclusion is added here.
13. Primary vs Secondary Estimands
| Question | Effect measure | What it captures |
|---|---|---|
| How frequently did COPD exacerbations occur? | Rate ratio | Relative modeled exacerbation rate over 52 weeks |
| How quickly did the first COPD exacerbation occur? | Hazard ratio | Relative instantaneous hazard of first exacerbation |
| How frequently did moderate/severe exacerbations occur? | Rate ratio | Relative modeled rate of moderate/severe exacerbations |
| How quickly did a first moderate/severe exacerbation occur? | Hazard ratio | Relative instantaneous hazard of first moderate/severe exacerbation |
| How quickly did specific treated or serious exacerbation events occur? | Hazard ratio | Relative instantaneous hazard for the specified first event |
This distinction is central to interpreting the page. A lower rate ratio and a lower hazard ratio can point in the same descriptive direction while still representing different statistical estimands. The values should therefore be reported with their exact endpoint definitions.
14. Limitations
- Analysis-population distinction: the primary endpoint was analyzed in the PPS, while the posted secondary analyses identify the FAS. These populations should not be treated as equivalent.
- Non-inferiority interpretation: the conclusion depends on the prespecified 1.15 margin and the confidence interval, not merely on whether the point estimate is below 1.
- Model dependence: the primary rate ratio comes from a generalized linear model assuming a negative binomial distribution, while secondary hazard ratios come from Cox models. Each estimate is conditional on its model assumptions.
- Proportional-hazards assumption: the Cox analyses summarize relative event hazards with a single HR. The ClinicalTrials.gov record does not provide a diagnostic assessment of proportional hazards.
- Missing data: the registry references multiple imputation / missing data, but the ClinicalTrials.gov record does not specify a complete imputation strategy.
- Endpoint multiplicity: multiple secondary endpoints were analyzed with superiority hypotheses. The ClinicalTrials.gov record does not provide enough information to reconstruct a complete multiplicity-adjustment strategy, so the individual secondary p-values should not automatically be interpreted as a single familywise-error-controlled collection.
- Precision of specific endpoints: the re-hospitalization endpoint has a 95% CI of 0.38–2.10, illustrating substantial uncertainty around its point estimate.
- Safety detail: the ClinicalTrials.gov record reports serious adverse events by arm but do not provide formal statistical comparisons or a broader safety table.
- Registry scope: the ClinicalTrials.gov record does not include a complete baseline-characteristic table, detailed subgroup analyses, or sufficient underlying data to reconstruct Kaplan-Meier curves.
15. Why This Trial Matters Statistically
FLAME is a useful teaching case because the primary analysis combines a recurrent-event rate endpoint with a prespecified non-inferiority margin and a subsequent superiority assessment. The secondary analyses then show how closely related clinical questions can require different statistical estimands.
| Concept | How it appears in FLAME |
|---|---|
| Randomization | Randomized phase 3 parallel-group design |
| Triple masking | Registry identifies the trial as triple-masked |
| Rate ratio | Primary COPD exacerbation rate and moderate/severe exacerbation-rate analyses |
| Negative binomial model | Primary rate analysis assumes a negative binomial distribution |
| Non-inferiority | Upper confidence limit compared with a 1.15-fold margin |
| Superiority | After non-inferiority, the same CI is evaluated against 1 |
| Per-protocol analysis | Primary endpoint analyzed in the PPS |
| Full analysis set | Posted secondary analyses identify the FAS |
| Missing data | Model inclusion requires non-missing values; multiple imputation / missing data is identified as an analysis concept |
| Cox model | Used for multiple time-to-first-exacerbation endpoints |
| Hazard ratio | Primary effect measure for the posted time-to-event analyses |
| Confidence intervals | 95% two-sided intervals are reported for all posted effect estimates |
| P-values | Posted for the superiority analyses of the primary and secondary endpoints |
16. Statistical Interpretation of the Main Findings
The primary rate ratio of 0.89 summarizes the modeled relative rate of COPD exacerbations. The confidence interval of 0.83–0.96 provides the precision of that estimate. It does not translate directly into an absolute number of exacerbations prevented for an individual patient.
The trial's prespecified non-inferiority criterion was based on excluding a 1.15-fold increase. Because the upper confidence limit was 0.96, the posted result satisfies that criterion. This is a margin-based inference rather than a conventional superiority p-value interpretation.
After non-inferiority, the upper limit of the same confidence interval was below 1, and the posted superiority analysis reported P = 0.003. The p-value supplies evidence for the statistical comparison; the rate ratio and confidence interval describe the magnitude and precision of the effect.
The posted secondary time-to-first-exacerbation analyses include HR estimates of 0.84 for first COPD exacerbation and 0.78 for first moderate to severe COPD exacerbation. These are different estimands from the recurrent exacerbation rate ratio and should be interpreted on their own endpoint definitions.
17. Results Across the Posted Endpoints
| Endpoint | Measure | Estimate | 95% CI | P-value |
|---|---|---|---|---|
| Rate of COPD Exacerbations | Rate ratio | 0.89 | 0.83–0.96 | 0.003 for superiority analysis |
| Time to First COPD Exacerbation. | HR | 0.84 | 0.78–0.91 | <0.001 |
| Rate of Moderate to Severe COPD Exacerbations. | Rate ratio | 0.83 | 0.75–0.91 | <0.001 |
| Time to First Moderate to Severe COPD Exacerbation. | HR | 0.78 | 0.70–0.86 | <0.001 |
| Time to First Moderate to Severe COPD Exacerbations Requiring Treatment With Systemic Corticosteroids | HR | 0.90 | 0.74–1.08 | 0.256 |
| Time to First Moderate to Severe COPD Exacerbations Requiring Treatment With Antibiotics | HR | 0.81 | 0.69–0.95 | 0.008 |
| Time to First Moderate to Severe COPD Exacerbations Requiring Hospitalization | HR | 0.81 | 0.66–1.00 | 0.046 |
| Time to First Moderate to Severe COPD Exacerbations Requiring Re-hospitalization Within 30 Days | HR | 0.89 | 0.38–2.10 | 0.790 |
The table demonstrates an important statistical principle: the results do not all have identical precision or identical endpoint definitions. In particular, the confidence interval for re-hospitalization within 30 days is substantially wider than the interval for first COPD exacerbation. The appropriate interpretation therefore considers the estimate, endpoint, confidence interval, and analysis population together.
18. Related Tutorials
Learn more about the methods used in this trial:
19. Related Statistical Calculators
20. Sources
- ClinicalTrials.gov: NCT01782326.
- Linked PubMed publication: PMID 41402044.
- Linked PubMed publication: PMID 38992490.
- Linked PubMed publication: PMID 32321518.
- Linked PubMed publication: PMID 30621717.
- Linked PubMed publication: PMID 30019939.
Continue through the Clinical Biostats statistical tutorials
Use the trial's endpoints and methods as a practical pathway into survival analysis, generalized linear models, non-inferiority design, confidence intervals, and clinical-trial methodology.
21. Record Summary
FLAME provides a compact example of several important clinical-trial statistical principles. Its primary endpoint was a 52-week rate of COPD exacerbations, analyzed with a negative-binomial generalized linear model in the per-protocol set. The posted rate ratio was 0.89 with a 95% CI of 0.83–0.96. Because the upper confidence limit was below the prespecified 1.15 non-inferiority margin, the registry's stated criterion for non-inferiority was met; the same upper limit was also below 1, and the posted superiority analysis reported P = 0.003.
The secondary analyses demonstrate why endpoint definition matters. Recurrent exacerbation rates were analyzed with a rate ratio, while time-to-first events were analyzed with Cox proportional-hazards models. The posted hazard ratios ranged from 0.78 to 0.90 for several secondary endpoints, while the re-hospitalization endpoint had a much wider 95% CI of 0.38–2.10. These results should be read with their exact endpoint definitions and analysis populations rather than treated as interchangeable measures of one underlying effect.
The statistical story is therefore broader than the headline p-value. Understanding FLAME requires attention to the estimand being analyzed, the non-inferiority margin, the confidence interval, the distinction between rate ratios and hazard ratios, the difference between the PPS and FAS, and the assumptions behind the negative-binomial and Cox models.