July 01, 2019

Weight may impact effectiveness of aspirin therapy

Doctors commonly recommend daily therapy with low-dose aspirin to prevent first or recurrent heart attacks and strokes. But a new study shows that your weight may be an important factor of effectiveness of aspirin therapy.

The study, published in the Aug. 4, 2018, issue of The Lancet, looked at data from nine clinical trials on aspirin use to prevent an initial heart attack or stroke — a practice known as primary prevention. While low-dose aspirin of 75 to 100 milligrams (mg) proved effective for those at lower weights, standard doses of of 300 to 325 mg reduced cardiovascular risk in people weighing 154 pounds or more. High doses of 500 mg or more reduced cardiovascular risk in people weighing about 198 pounds or more.

Analyzing the data on aspirin's role in preventing a subsequent heart attack or stroke (secondary prevention) yielded similar results. So did its role in the long-term prevention of colorectal cancer.

A particular concern with daily aspirin therapy is the risk of gastrointestinal bleeding. Since higher doses of aspirin are associated with an increased risk of this, it's predicted that weight-based dosing may increase bleeding risk in some people. More research is needed to assess the risks and benefits of weight-based dosing before firm recommendations can be rolled out.

Mayo Clinic experts caution not to start or stop taking aspirin or change the dosage until you talk to your doctor about your specific circumstances. The decision to start or continue low-dose aspirin therapy is based on a number of factors....