See next blog posting for the new studies, this is background.
As with many medical studies the results of studies on men and women and low dose aspirin are confusing and sometimes contradictory but remember that the newest studies published in peer-reviewed journals such as the NEJM or The Lancet, Nature, and Science, are built on the information obtained from the earlier studies and are therefore likely to be correct even when they contradict the older studies.
Studies of the results for women and girls are especially important because until recently most studies were conducted on men and only in recent years has it been shown that the results for women can vary greatly from those for men. That one chromosome is very important.
A randomized trial published in the NEJM in 2005 found only a tiny, 9% improvement in preventing initial heart attacks in women so the new studies should be considered especially important for women when considering the proven risks vs the small potential benefits of low dose aspirin therapy.
https://www.nejm.org/doi/full/10.1056/NEJMoa050613
Quoted from NEJM:
"BACKGROUND
Randomized trials have shown that low-dose aspirin decreases the risk of a first myocardial infarction in men, with little effect on the risk of ischemic stroke. There are few similar data in women.
METHODS
We randomly assigned 39,876 initially healthy women 45 years of age or older to receive 100 mg of aspirin on alternate days or placebo and then monitored them for 10 years for a first major cardiovascular event (i.e., nonfatal myocardial infarction, nonfatal stroke, or death from cardiovascular causes)."
and
"Although aspirin is effective in the treatment of acute myocardial infarction and in the secondary prevention of cardiovascular disease among both men and women,1 its use in primary prevention remains controversial. To date, five randomized trials involving 55,580 participants have evaluated aspirin in the primary prevention of cardiovascular disease.2-6 In aggregate, these trials indicate that, as compared with placebo, aspirin therapy was associated with a significant, 32 percent reduction in the risk of myocardial infarction, but the data on the risk of stroke and death from cardiovascular disease remains inconclusive.7Moreover, three of these trials evaluated men exclusively, and fewer than 180 of the 2402 vascular events occurred in women. Thus, at this time, the current recommendations for the use of aspirin in primary prevention in women are based on limited direct data from women"
