Women's Health Study:
Low-Dose Aspirin in Primary Prevention Trial
Women's Health Study:
Low-Dose Aspirin in Primary Prevention
Presented at
American College of Cardiology
Scientific Sessions 2005
Presented by Dr. Dr. Paul M. Ridker
Women's Health Study:
Low-Dose Aspirin in Primary Prevention Trial
39,876 initially healthy† women age ≥ 45
Randomized, blinded, factorial
Placebo
n=19,942
Low-dose Aspirin
100mg on alternate days
n=19,934
Endpoints (mean 10.1 years):

Combined endpoint of nonfatal MI, nonfatal stroke, and total cardiovascular death.
Incidence of total malignant neoplasms of epithelial cell origin.

†: No history of coronary heart disease, cerebrovascular disease, cancer (except nonmelanoma skin cancer), or other major chronic illness;
no history of side effects to any of the study medications; not taking aspirin or nonsteroidal antiinflammatory medications (NSAIDs) more
than once a week (or were willing to forego their use during the trial); not taking anticoagulants or corticosteroids; and not taking individual
supplements of vitamin A, E, or beta carotene more than once a week.
www. Clinical trial results.org
Presented at ACC Scientific Sessions 2005
Women's Health Study:
Low-Dose Aspirin in Primary Prevention Trial
Composite Components:
Primary Composite Endpoint:
Major Cardiovascular Events
p=0.83
300
600
500
Death
from CV
Causes
MI
Relative Risk [RR] 0.91
95% CI 0.80-1.03
p=0.13
Stroke
p=0.04
p=0.68
266
522
250
477
400
200
300
150
200
100
100
50
0
0
Aspirin
Placebo
221
198
193
120
Aspirin Placebo
126
Aspirin Placebo
Aspirin Placebo
• Baseline characteristics were well matched between the two treatment groups.
• Among the individual components of the composite endpoint, there was no difference in MI
or death from cardiovascular causes, but total stroke was lower in the aspirin group.
www. Clinical trial results.org
Presented at ACC Scientific Sessions 2005
Women's Health Study:
Low-Dose Aspirin in Primary Prevention Trial
Components of Stroke
Ischemic Stroke
p=0.009
Transient Ischemic
Attack
p=0.01
Hemorrhagic
Stroke
Gastrointestinal
Bleeding Requiring
Transfusion
p=0.02
p=0.31
238
250
200
221
186
170
150
127
91
100
51
50
41
0
Aspirin
Placebo
Aspirin
Placebo
Aspirin
Placebo
Aspirin
Placebo
• Total stroke was lower in the aspirin group due to a reduction in ischemic stroke.
• Transient ischemic attack was lower in the aspirin group, but there was a higher
incidence of gastrointestinal bleeding requiring transfusion.
www. Clinical trial results.org
Presented at ACC Scientific Sessions 2005
Women's Health Study:
Low-Dose Aspirin in Primary Prevention Trial
Primary Composite Endpoint
(age ≥ 65)
Gastrointestinal Bleeding
(age ≥ 65)
p=0.008
p=0.05
16
44
Aspirin
Placebo
Aspirin
Placebo
• In the subgroup analysis, the primary endpoint was lower in women age ≥65 years
(n=4097) (RR 0.74, p=0.008), but did not differ in women <65 years (p<0.001 for
interaction).
• Additionally, the primary endpoint was lower in women who were former or never smokers
(RR 0.80, p=0.003) but was higher in current smokers (RR 1.30, p=0.03; p<0.001 for
interaction).
www. Clinical trial results.org
Presented at ACC Scientific Sessions 2005
Women's Health Study:
Low-Dose Aspirin in Primary Prevention Trial
• Among initially healthy women, treatment with low-dose aspirin was not
associated with a significant difference in the primary endpoint of major
cardiovascular events compared with placebo at a mean 10 year follow-up.
• Low-dose aspirin has been shown to be effective for secondary prevention
following acute coronary syndromes, but data for primary prevention with
aspirin in women were limited. The Physicians' Health Study, a randomized
trial of aspirin for primary prevention conducted in male physicians showed a
reduction in MI and a trend toward an increase in total stroke, unlike the
present trial in women which showed no difference in MI and a reduction in
total stroke. It is unclear why gender-related differences in aspirin therapy for
primary prevention may exist.
• Benefit with aspirin therapy was observed in the subgroup of women age ≥65
years and non-smokers.
www. Clinical trial results.org
Presented at ACC Scientific Sessions 2005