METHODS

Design:

randomised, placebo controlled trial (Women’s Health Study).

Allocation:

{concealed*}†.

Blinding:

blinded {healthcare providers, participants, data collectors, and outcome assessors}†.*

Follow up period:

mean 10 years.

Setting:

USA and Puerto Rico.

Participants:

39 876 women ⩾45 years of age (mean age 55 y) who had no history of coronary artery disease, cerebrovascular disease, cancer (except non-melanoma skin cancer), or other major chronic illness; contraindication to the study medications; were not taking aspirin, non-steroidal anti-inflammatory drugs, anticoagulants, or corticosteroids; and were not taking vitamin A or E, or ß carotene supplements more than once per week.

Intervention:

aspirin, 100 mg every other day (n = 19 934) or placebo (n = 19 942).

Outcomes:

first major cardiovascular event (non-fatal myocardial infarction, non-fatal stroke, or cardiovascular death); individual cardiovascular endpoints; and adverse events.

Patient follow up:

97% (intention to treat analysis).

MAIN RESULTS

The table shows …