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
CONFIRM-HF was a randomized, double-blind, parallel phase 4 trial evaluating ferric carboxymaltose compared with placebo in patients with chronic heart failure and iron deficiency.
| Feature | CONFIRM-HF |
|---|---|
| Condition | Iron Deficiency; Chronic Heart Failure |
| Design | Randomized, double-blind, parallel |
| Primary purpose | Treatment |
| Intervention | Ferinject (ferric carboxymaltose) |
| Comparator | Placebo (saline) |
| Sponsor | Vifor Pharma |
2. Clinical Question
Population
Patients with chronic heart failure and iron deficiency.
Intervention
Ferric carboxymaltose (Ferinject).
Comparator
Placebo (saline).
Primary question
Does ferric carboxymaltose change six minute walk test performance from baseline to week 24 compared with placebo?
3. Trial Design
Randomized
Double
Parallel
Start date: 2011-10
Primary completion: 2014-02
4. Trial Arms
| Arm | Description |
|---|---|
| Intervention | Ferinject (ferric carboxymaltose) (drug) |
| Comparator | Placebo (saline) (drug) |
5. Endpoints
| Endpoint | Definition | Time frame |
|---|---|---|
| Primary endpoint | Change in six minute walk test from baseline to week 24 | 24 weeks |
6. Planned Analysis
The registry identifies change in six minute walk test from baseline to week 24 as the primary endpoint. A continuous change-from-baseline endpoint of this type is commonly evaluated by comparing mean changes between randomized groups, often using a regression-based approach such as analysis of covariance when baseline measurements are incorporated.
7. Statistical Methodology
Randomized treatment comparison
Randomization creates the framework for comparing outcomes between treatment groups while reducing the influence of measured and unmeasured baseline differences.
Continuous outcomes
The six minute walk test is a continuous functional measure. Statistical analysis focuses on differences in average change between groups rather than event counts or time-to-event measures.
The treatment comparison evaluates whether average change differs between randomized groups.
Confidence intervals
Confidence intervals describe uncertainty around an estimated treatment difference. They provide information about precision rather than the probability that a particular hypothesis is true.
8. Statistical Methods Explained
Why use a change-from-baseline endpoint?
Change scores summarize improvement or decline relative to each participant's starting measurement. This can account for differences in baseline functional status.
Why does randomization matter?
Randomization supports an unbiased comparison because treatment assignment is determined by the study design rather than patient characteristics.
What would an adjusted analysis provide?
A baseline-adjusted model can improve precision by accounting for the starting value of the outcome measure.
Why is the six minute walk test a continuous endpoint?
Unlike binary outcomes such as response/no response, a walking distance measurement contains information across a range of values.
What does a treatment difference mean?
A difference in mean change represents the estimated average separation between randomized groups. It does not describe the response of every individual participant.
9. Limitations
- Outcome reporting: The registry does not provide posted statistical analyses or numerical outcome estimates.
- Endpoint scope: The primary endpoint is limited to change in six minute walk test from baseline to week 24.
- Generalizability: Applicability depends on how closely other populations resemble the enrolled trial population.
10. Why This Trial Matters Statistically
| Concept | Application in CONFIRM-HF |
|---|---|
| Randomization | Randomized comparison of ferric carboxymaltose and placebo |
| Blinding | Double-blind design |
| Continuous endpoint | Change in six minute walk test |
| Longitudinal measurement | Baseline to week 24 comparison |
11. Sources
- ClinicalTrials.gov record: NCT01453608
- Publication: PubMed record