Aspirin has conventionally been used to prevent heart disease, stroke, and death in patients with heightened risk. Many physicians have assumed that higher doses are likely more effective than lower doses when used prophylactically. However, a new study published in the New England Journal of Medicine has produced surprising results that suggest that this may in fact not be the case.

The study investigated more than 15,000 patients who were followed on average for just over 2 years to compare the effects of 81 mg of daily aspirin and 325 mg of daily aspirin. The results showed that there was no significant difference in terms of cardiovascular events or major bleeding in those who took the 81 mg dose versus those who took the 325 mg dose.

Interestingly, there was one difference between the groups. Those who took the lower dose of aspirin were more likely to continue their medication. On the other hand, those taking the higher close were more likely to switch to the lower dose or to quit taking aspirin altogether.

Because aspirin is valuable for preventing blood clots, it is recommended for people at known risk for developing such clots. However, because aspirin can also increase risks for problematic bleeding, it is not recommended for those who are healthy and have no known heightened risk for clots.

This new study, however, adds important information to the story of using aspirin prophylactically. Though the medical impact of low and high dose may be indistinguishable, the patient preference for lower doses may suggest that lower doses are more likely to be effective in the long run simply because patients are more likely to be adherent when prescribed lower doses.

Reference

Jones WS, Mulder H, Wruck LM, et al. Comparative Effectiveness of Aspirin Dosing in Cardiovascular Disease. New England Journal of Medicine. 2021;384(21):1981-1990. doi:10.1056/nejmoa2102137