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Table 1 Randomised controlled trials which have compared aspirin with adjusted dose warfarin in the treatment of atrial fibrillation

From: Protocol for Birmingham Atrial Fibrillation Treatment of the Aged study (BAFTA): a randomised controlled trial of warfarin versus aspirin for stroke prevention in the management of atrial fibrillation in an elderly primary care population [ISRCTN89345269]

Study

Population

Age

Interventions

Primary end-point

Relative risk of primary end-point (95% CI)

AFASAK I [15].

Primary care. N = 671 (in relevant arms)

No age limits. Mean age 74 yrs.

3 arm study including warfarin (INR 2.8–4.2) and aspirin (75 mg).

Stroke, transient ischaemic attack and systemic embolus.

Not given. RR on warfarin as compared to aspirin or placebo: 0.36

EAFT [14].

TIA or minor stroke in preceding 3/12 N = 455 (in relevant arms)

65% were >69 yrs

3 arm study, including anti-coagulant (INR 2.5–4.0) and aspirin (300 mg).

Death from vascular disease; non-fatal stroke (including haemorrhage); non-fatal myocardial infarction or systemic embolus

0.60 (0.41 to 0.87)

SPAF II [16].

N = 385

>75 yrs

Warfarin (INR 2.0–4.5) vs aspirin (325 mg).

Ischaemic stroke and systemic embolus

0.73 (0.37 to 1.5) 1.07 (stroke with residual deficit including haemorrhagic)

AFASAK II [8].

Primary care. N = 339 (in relevant arms)

No upper age limit. Mean age 73 yrs.

3 arm study, including warfarin (INR 2.0–3.0) and aspirin (300 mg) arms.

Stroke (ischaemic or haemorrhagic) or systemic thrombo-embolus.

1.26 (intention to treat) 0.78 (treatment received analysis)

SIFA [43].

Recent cerebral ischaemia N = 916

Age > 30 yrs Mean age 72 yrs.

Warfarin (INR 2.0–3.5) vs indobufen (200 mg bd or 100 mg bd if creatinine clearance < 80 mls/min).

Stroke (including haemorrhagic), myocardial infarction, pulmonary embolus, systemic embolus or vascular death

0.85 (not significant)

SPAF III [6].

At least 1 risk factor for stroke N = 1044

No upper age limit. Mean age 71 yrs.

Warfarin (INR 2.0–3.0) vs aspirin (325 mg) and fixed mini-dose warfarin (INR 1.2–1.5).

Ischaemic stroke and systemic embolus

0.26 (0.13 to 0.50)

PATAF [9].

Primary care. N = 272 (in relevant arms)

Age 60–78. Mean age 70 yrs.

3 arm study including warfarin (INR 2.5–3.5) and aspirin (150 mg).

Stroke, systemic embolus, major haemorrhage or vascular death.

0.78 (0.34 to1.8)

  1. [In the relative risk column, the risk of an end-point on variable dose warfarin is compared to the risk on aspirin (and fixed-minidose warfarin in the case of SPAF-III). Thus, a relative risk greater than one favours aspirin, and a relative risk less than one favours warfarin]