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Aspirin for Primary Cardiovascular Prevention in Women

In healthy middle-aged women, aspirin lowered risks for strokes and TIAs but not for MIs and cardiovascular death.

In several primary prevention trials, aspirin has been shown to reduce risk for a first myocardial infarction; however, only a small proportion of subjects in these trials have been women. Now, data from the Women's Health Study provide additional information.

Nearly 40,000 generally healthy women (age, 45; mean age, 55) with no history of coronary or cerebrovascular disease were randomized to receive either aspirin (100 mg every other day) or placebo. During an average follow-up of 10 years, aspirin therapy, compared with placebo, was associated with the following outcomes:

• a nonsignificant decrease in the combined endpoint of nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death (2.4% vs. 2.6%, P=0.13)
  
• significant decreases in stroke rate (1.1% vs. 1.3%, P=0.04) and transient ischemic attack rate (0.9% vs. 1.2%, P=0.01)
  
• no difference in MI (1.0% in both groups)
  
• no difference in all-cause or cardiovascular mortality rates
  

The combined endpoint was significantly lower in the aspirin group among older women (age, >65) but not among younger women. Interestingly, women with multiple cardiovascular risk factors did not derive more benefit than did women with few or no risk factors.

Gastrointestinal bleeding occurred significantly more often in aspirin recipients than in placebo recipients (4.6% vs. 3.8%); excess risk for GI bleeding that led to transfusions was about 2 per 1000 aspirin recipients.

Comment: In this primary prevention trial in mainly healthy middle-aged women, aspirin did not significantly reduce the incidence of a composite cardiovascular endpoint, but it did lower risk for stroke and transient ischemic attacks. However, even this low dose caused a slight excess of GI bleeding events. The results suggest a primary preventive role for aspirin in women -- especially women older than 65 -- but the magnitude of the benefit is quite small.

— Allan S. Brett, MD

Published in Journal Watch General Medicine March 18, 2005

Citation(s):

Ridker PM et al. A randomized trial of low-dose aspirin in the primary prevention of cardiovascular disease in women. N Engl J Med 2005 Mar 31; 352:1293-304. (http://content.nejm.org/cgi/content/abstract/NEJMoa050613)

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