Table.

Characteristics of studies included in meta-analysis

Study	Year	Aspirin formulation	Dose (mg/day)	Average treatment duration (months)	Indication for aspirin therapy
Diener et alw1 w2	1996	Unspecified	50	24	Transient ischaemic attack or stroke
Hansson et alw3	1998	Standard	75	45	Hypertension
Petersen et alw4	1989	Unspecified	75	24	Atrial fibrillation
SALTw5	1991	Standard	75	32	Transient ischaemic attack or stroke
TPTw6	1998	Modified release	75	81	Cardiovascular risk factors
Wallentinw7	1991	Unspecified	75	12	Unstable angina
Silagy et alw8	1993	Standard	100	12	Primary prevention
USPHSw9	1989	Standard	162.5	60	Primary prevention
EAFTw10	1993	Unspecified	300	28	Transient ischaemic attack or stroke
Elwood et alw11	1974	Standard	300	12	Myocardial infarction
UK-TIAw12	1991	Various	300, 1200	48	Transient ischaemic attack
Gavaghan et alw13	1991	Standard	324	12	Coronary artery bypass grafting
Olivotto et alw14	1996	Modified release	325	12	Breast cancer
Elwood et alw15	1979	Standard	900	12	Myocardial infarction
CDPAw16	1976	Unspecified	972	22	Myocardial infarction
PARISw17	1980	Unspecified	972	41	Myocardial infarction
Hess et alw18	1985	Unspecified	990	24	Peripheral vascular disease
AMISw19	1980	Standard	1000	36	Myocardial infarction
Breddin et alw20	1980	Modified release	1000	24	Myocardial infarction
CCSGw21	1978	Standard	1300	26	Transient ischaemic attack
Fields et alw22	1977	Standard	1300	24	Transient ischaemic attack
Fields et alw23	1978	Standard	1300	24	Transient ischaemic attack
Brittonw24	1987	Modified release	1500	24	Stroke
Ehresman et alw25	1977	Modified release	1500	12	Peripheral vascular disease

SALT=Swedish aspirin low dose trial; TPT=thrombosis prevention trial; USPHS=US physicians health study; EAFT=European atrial fibrillation trial; UK-TIA=UK transient ischaemic attack aspirin trial; CDPA=coronary drug project aspirin study; PARIS=persantine-aspirin reinfarction study; AMIS=aspirin myocardial infarction study; CCSG=Canadian Cooperative Study Group.