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
CLOTS 3 was a phase 3 randomized clinical trial evaluating intermittent pneumatic compression as a device-based prevention strategy for deep vein thrombosis after stroke.
| Feature | CLOTS 3 |
|---|---|
| NCT ID | NCT00789542 |
| Title | A RCT to Establish the Effectiveness of Intermittent Pneumatic Compression to Prevent Post Stroke DVT |
| Status | Completed |
| Sponsor | University of Edinburgh |
| Condition | Stroke |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
2. Clinical Question
Population
Patients with stroke enrolled in a prevention trial.
Intervention
Intermittent pneumatic compression device.
Comparator
Routine care.
Primary question
Does intermittent pneumatic compression affect the occurrence of deep vein thrombosis after stroke?
3. Trial Design
Patients were assigned in a randomized design.
The trial used a parallel design with two intervention arms.
The registry classified the study purpose as prevention.
Start date: 2008-12. Primary completion date: 2013-01.
Intermittent Pneumatic Compression
Device intervention arm.
Routine Care
Other intervention comparator arm.
4. Endpoints
| Endpoint | Time Frame |
|---|---|
| Presence of definite/probable symptomatic/asymptomatic DVT in the popliteal or femoral veins (PFV) or any symptomatic DVT in the PFV | 30 days of randomisation |
5. Planned Analysis
The ClinicalTrials.gov record identifies the primary endpoint but does not report posted statistical analyses or outcome estimates.
For an endpoint based on occurrence of deep vein thrombosis, statistical analysis would typically compare event proportions between randomized groups using an appropriate binary outcome method. Depending on the prespecified statistical analysis plan, this could include risk differences, risk ratios, odds ratios, or regression-based approaches.
No formal statistical analyses were posted to ClinicalTrials.gov.
6. Statistical Methodology
Randomized comparison
Randomization is intended to create comparable groups at baseline so that differences in outcomes can be attributed to the assigned interventions rather than measured or unmeasured differences between participants.
Binary endpoint analysis
The primary endpoint is a dichotomous outcome: presence or absence of DVT within a defined follow-up period. Binary outcomes summarize whether an event occurred during the specified assessment window.
This type of analysis focuses on comparing event occurrence between randomized groups.
Time frame matters
The endpoint definition specifies assessment within 30 days of randomisation. Restricting interpretation to the prespecified window prevents mixing outcomes measured at different follow-up periods.
7. Statistical Methods Explained
Why is randomization important?
Randomization reduces systematic differences between treatment groups and provides the foundation for an unbiased comparison of outcomes.
Why define the endpoint as DVT within 30 days?
A fixed assessment window creates a consistent comparison period across randomized groups.
Why use a binary outcome analysis?
The primary endpoint records whether DVT was present or absent, making methods for categorical outcomes appropriate.
What does an event rate represent?
An event rate describes the proportion of participants experiencing the outcome during the defined follow-up period.
8. Limitations
- The registry record does not report posted statistical analyses or numerical outcome estimates.
- The available record does not provide baseline characteristics, subgroup analyses, or safety results.
- Without posted results, comparative treatment effects cannot be quantified from the registry information.
9. Why This Trial Matters Statistically
CLOTS 3 is a useful example of how prevention trials evaluate interventions using clearly defined clinical events. The statistical framework illustrates several core principles:
| Concept | Application |
|---|---|
| Randomization | Creates the basis for comparison between intervention groups. |
| Binary outcomes | DVT presence within a specified period is measured as an event outcome. |
| Endpoint definition | Precise event definitions determine what is counted as a trial outcome. |
| Follow-up window | Thirty-day assessment defines the period of interest. |
10. Sources
- ClinicalTrials.gov: CLOTS 3 (NCT00789542)