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How should results from completed studies influence ongoing clinical trials? The CAFA Study experience
A Laupacis1, S J Connolly, M Gent
1Clinical Epidemiology Unit, Loeb Research Institute, Ottawa Civic Hospital, Ontario.
Annals of Internal Medicine
|November 15, 1991
Summary
Warfarin significantly reduces embolic events in nonrheumatic atrial fibrillation patients. Published study results prompted the Canadian Atrial Fibrillation Anticoagulation study to halt recruitment due to compelling evidence of warfarin
Area of Science:
- Cardiology
- Clinical Trials
- Pharmacology
Background:
- Nonrheumatic atrial fibrillation poses a significant risk of embolic events.
- Anticoagulant therapy, including warfarin and aspirin, is evaluated for stroke prevention.
Purpose of the Study:
- To assess the impact of early published trial results on ongoing anticoagulant studies.
- To determine the appropriate course of action for the Canadian Atrial Fibrillation Anticoagulation (CAFA) study based on emerging evidence.
Main Methods:
- Review of seven randomized studies on warfarin or aspirin efficacy in nonrheumatic atrial fibrillation.
- Analysis of two published studies demonstrating warfarin's benefit in reducing embolic events.
- Consideration of multiple options by the CAFA Steering Committee regarding study continuation.
Main Results:
- Two published studies showed warfarin significantly decreased embolic events with minimal bleeding.
- The compelling evidence from published trials led the CAFA Steering Committee to stop recruitment.
- The decision was made without preliminary analysis of CAFA's own data.
Conclusions:
- Published evidence on warfarin's efficacy in nonrheumatic atrial fibrillation is clinically significant.
- Ongoing trials should consider external data to guide their protocols.
- The CAFA study halted recruitment based on the strength of existing published evidence.
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