By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program
of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.

Many people are advised to take one aspirin a day to prevent strokes and heart attacks, but there has been some uncertainty as to what the appropriate dose should be, particularly for the prevention of stroke. In previous studies the dose has varied from 75 milligrams (a ‘baby’ aspirin) to 1300 milligrams (four whole aspirins). For the prevention of heart attacks, there is no evidence that the bigger doses give any better protection, although they certainly do cause more stomach bleeding.

Now an internationally conducted study of patients who were undergoing surgery for blockage of the carotid artery (carotid endarterectomy) has compared the rates of strokes and heart attacks after the surgery in 2849 patients, who were randomly allocated to one of four doses ranging from one baby aspirin (75 milligrams) to 1300 milligrams. The main finding was that the combined rates of stroke, heart attack, and death after three months was lower in the groups given the lower doses (6.2%) than the higher doses (8.4%). The authors concluded that 75 milligrams is the ideal dose.

Doctor’s comments

This study provides further support for the view that people who are advised to take aspirin for the prevention of strokes and heart attacks (principally those who are at high risk because of known disease of the arteries, such as the patients in this study) should take the low dose , usually referred to as a baby aspirin. This dose is typically 75 or 81 milligrams. This does not mean that everyone should take aspirin; your doctor can advise you on this.

Where it was published

DW Taylor and colleagues. Low-dose and high dose acetylsalicylic acid for patients undergoing carotid endarterectomy: a randomised controlled trial. Lancet 353;2179, 1999.