Aspirin for Primary prevention in women

Ridker PM, Cook NR, Lee I, et al. A randomized trial of low dose aspirin in the primary prevention of cardiovascular disease in women. NEJM 2005; 352:1293-1304. article with associated editorial by Levin RI The Puzzle of aspirin and sex NEJM 352:1366-1368.

Background: Low dose asa reduces the risk of a first MI in men, with little effect on risk of ischemic stroke. There are no similar data in women.

Article highlights: This large (39,876) trial of healthy women age 45 and older for primary prevention put them in a group of ASA 100 mg or placebo for ten years. ASA reduced the risk of stroke without affecting the risk of MI/death from cardiovascular causes, leading to a nonsignificant primary endpoint.

Editorial: the finding is the inverse in what they found in men. The author discusses that the studies were done in different decades (2 decades apart) and that the respective placebo groups had different risk profiles. The risk was 97/100000 person years in the Women's Health Study and 439 per 100,000 py's in the Physicians Health Initiiative (the male study). These were healthy women. The author reviews some of the pertinent differences in physiology by gender. Men usually have 2-3 times the number of MI's as women. Their coronary arteries are bigger and their carotid plaques "more aged." Women have 9 times the amount of stress cardiomyopathy . Their responses to drugs are different. Estrogen up-regulates prostacyclin by receptor mediated activation of cyclo-oxygenase 2. The study would seem to suggest that generally prescribing low dose aspirin to healthy women under 65 with a low risk score should be avoided. However, part of the book has yet to be written.