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
HYVET was a randomized, parallel-group, quadruple-masked phase 4 trial evaluating antihypertensive therapy for hypertension in very elderly patients.
| Feature | HYVET |
|---|---|
| Condition | Hypertension |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Primary purpose | Prevention |
| Lead sponsor | Imperial College London |
| Sponsor type | Other |
2. Clinical Question
Population
Patients with hypertension enrolled in the Hypertension in the Very Elderly Trial.
Intervention
Indapamide SR 1.5mg and Perindopril 2-4mg.
Comparator
The registry identifies the randomized trial design but does not report comparator details in the available record.
Primary question
The trial evaluated whether the intervention affected the occurrence of all strokes (fatal and non-fatal).
3. Trial Design
Participants were randomly allocated.
The study used quadruple masking.
Parallel-group design.
Prevention.
4. Endpoints
| Endpoint | Definition | Time Frame |
|---|---|---|
| All strokes (fatal and non-fatal) | Primary endpoint | Duration of trial |
5. Planned Analysis
The registry identifies the primary endpoint as all strokes (fatal and non-fatal) over the duration of the trial. No results or posted statistical analyses are available in the ClinicalTrials.gov record.
For a randomized time-to-event cardiovascular endpoint such as stroke occurrence, analyses commonly compare event rates between randomized groups using survival-analysis approaches. These methods account for participants who may not experience the event before the end of follow-up or who have incomplete observation.
The analysis focuses on the timing of events rather than only whether an event occurred, allowing follow-up duration to contribute information.
6. Statistical Methodology
Randomization
Randomization creates treatment groups that can be compared without assigning treatment based on participant characteristics. This design supports causal interpretation of differences between randomized groups.
Time-to-event analysis
The primary endpoint is an event occurring over the duration of follow-up. Statistical methods for these endpoints typically incorporate censoring, where individuals contribute follow-up information until the last observed time if the event has not occurred.
Interpretation of hazard-based measures
When hazard ratios are used, they describe relative event rates over time under a statistical model. They do not directly represent the percentage of individuals who experience or avoid an event.
7. Statistical Methods Explained
Why is randomization important in HYVET?
Randomization reduces systematic differences between groups at baseline, allowing the comparison of outcomes to reflect the assigned intervention more directly.
Why analyze strokes over time instead of only counting strokes?
Time-to-event methods use both whether an event occurred and when it occurred, which is important when participants have different lengths of follow-up.
What does censoring mean?
Censoring occurs when follow-up ends before the event is observed. Appropriate statistical methods preserve the information contributed before that point.
Why does masking matter statistically?
Masking can reduce the influence of expectations on treatment administration, outcome assessment, and reporting.
Why are confidence intervals important?
Confidence intervals describe uncertainty around estimated treatment effects and help distinguish precise estimates from those with substantial uncertainty.
Why are registry endpoints important?
Prespecified endpoints define the outcomes the trial was designed to evaluate and help distinguish planned analyses from exploratory questions.
8. Limitations
- No posted statistical analyses: The ClinicalTrials.gov record does not provide endpoint estimates, confidence intervals, or p-values.
- Limited registry detail: The available record does not report baseline characteristics, subgroup analyses, safety results, or analysis populations.
- Endpoint interpretation: Stroke outcomes depend on event definitions, follow-up duration, and statistical handling of incomplete observations.
9. Why This Trial Matters Statistically
HYVET illustrates several foundational principles of randomized clinical trial analysis.
| Concept | Application |
|---|---|
| Randomization | Creates comparable intervention groups. |
| Masking | Reduces potential assessment and performance bias. |
| Time-to-event analysis | Appropriate framework for outcomes occurring over follow-up. |
| Clinical endpoints | Focuses evaluation on meaningful patient outcomes. |
10. Sources
- ClinicalTrials.gov record: NCT00122811