NEW YORK (Reuters Health) - Contrary to what many doctors prescribe, long-term aspirin therapy at doses greater than 75 to 81 mg per day does not enhance the prevention of heart disease but does increase the risk of stomach bleeding, new findings indicate.

According to the report in the Journal of the American Medical Association, over 50 million adults in the US are on long-term aspirin therapy for heart disease prevention, yet the optimal daily dose is still a point of controversy.

To determine the safest, most effective dose, Dr. Charles L. Campbell, from the University of Kentucky in Lexington, and colleagues performed a review of relevant studies identified through a search of the MEDLINE and EMBASE medical databases.

The authors found that while aspirin doses as high as 1300 mg per day are approved for clinical use, scientific data indicate that doses as low as 30 mg per day provide the full physiologic effect of higher doses. The most commonly prescribed dose in the US is 81 mg per day and then 325 mg per day.

Data from previous studies, primarily those focusing on preventing repeat heart attacks, indicate that use of aspirin doses above 75 to 81 mg per day do not increase effectiveness, but it do raise the risk of stomach bleeding.

"An association between increases in aspirin dose and risk of adverse events has been confirmed in multiple studies, whereas no such dose relationship has been identified for efficacy," the authors point out.

In the future, antiplatelet therapy will likely be tailored for the individual patient, they note.

SOURCE: Journal of the American Medical Association, May 9, 2007.

REUTERS