Aspirin for Primary Prevention of Cardiovascular Disease? Still a Very Close Call.

In patients with established cardiovascular disease, daily aspirin clearly lowers the incidence of adverse cardiovascular events. But do at-risk patients without histories of cardiovascular events also benefit? Several guidelines recommend daily aspirin for primary prevention in subgroups of such patients, but evidence of benefit has been sparse. In 2008 and 2009, two new randomized trials, three new meta-analyses, and a new guideline from the U.S. Preventive Services Task Force (USPSTF) added new information.

In one randomized trial, Scottish investigators assigned 1276 adults with diabetes and asymptomatic peripheral arterial disease (PAD) to receive daily aspirin or placebo for a median 7 years (JW Gen Med Nov 13 2008); in the other, Japa…