The U.S. Preventive Services Task Force have revised guidelines for aspirin intake stating that lower doses appear to be at least as effective as higher doses and safer at preventing heart attack and stroke.

Aspirin carries an increased risk of gastrointestinal bleeding, especially when taken in combination with the clot-dissolving drug clopidogrel (Plavix) and this has opened a lot of debate on the recommended dosage within safe limits.

Aspirin, according to background information in the study, is the most used drug worldwide to prevent heart attack and stroke with more than one-third of U.S. adults on daily aspirin doses.

The new guidelines have been made age and gender specific. Dr. Michael LeFevre, a task force member and professor of family and community medicine at the University of Missouri, Columbia said, "Subsequent to the 2002 recommendations, there was more information that came out of the Women's Health

Initiative, specifically, that enabled us to look at this recommendation by gender. We have a recommendation for men and a recommendation for women. We did not have that before."

LeFevre added that aspirin seemed more effective in men for preventing heart attack while in the case of women it was better at preventing stroke.

Under the new guidelines published in the March 17 issue of the Annals of Internal Medicine some of the recommendations made are:  for men ages 45 to 79 to take aspirin if there are benefits in preventing heart attacks which outweigh the risks of gastrointestinal bleeding. In the case of women those between the ages of 55 to 79 should consider taking the drug if the chances of reducing ischemic stroke are more than the risks of GI bleeding.

Men under the age of 45 and women under 55 who have never had a heart attack or stroke should avoid aspirin as prevention. Also the guidelines said that in the case of patients who were 80 or older, aspirin benefits weren’t clear. The task force emphasized that the recommendations only apply to people who have never had a heart attack or stroke.

Dr. Carl J. Lavie, medical director of cardiac rehabilitation at the Ochsner Heart and Vascular Institute in New Orleans said, "The benefits of aspirin use always have to be balanced against the risks. If a patient has low risk of events in the near future, aspirin should not be prescribed. If the risk is very high, clearly aspirin is needed."

Another paper published in the same issue of the journal echoes the task force guidelines and said that lower doses of daily aspirin which are between 75 milligrams to 81 milligrams are equally if not more effective in preventing heart attack and stroke in at-risk individuals as are higher doses of 100 mg or more. The paper also found a higher risk for people on higher doses of aspirin especially those who were taking Plavix.