Table 2

 Adjusted dose warfarin compared with placebo, or no treatment in non-rheumatic AF (modified from Hart and colleagues15)

StudyPreventionTarget INRWarfarin group: strokes/ person-yearsPlacebo group: strokes/ person-yearsRelative risk reduction (%)Absolute risk reduction per year (%)
BAATAF, Boston area anticoagulation trial for atrial fibrillation; EAFT, European atrial fibrillation trial; INR, international normalised ration; SPAF, stroke prevention in atrial fibrillation.
*95% confidence interval.
Petersen10Primary2.8–4.29/41319/336542.6
SPAF5Primary2.0–4.58/26319/245604.7
BAATAF11Primary1.5–2.73/48713/435782.4
Connolly12Primary2.0–3.06/2379/241331.2
Ezekowitz13Primary1.4–2.87/48923/483703.3
EAFT14Secondary2.5–4.020/50750/405688.4
All trials53/2396133/220762 (48 to 72)*3.1