Aspirin: When should it be used for prevention of cardiovascular events?

Physicians debated the benefits versus the risks of aspirin for cardiovascular events in an editorial published in JAMA online November 17.

J. Michael Gaziano, MD, MPh, associate editor of JAMA, physician at Brigham and Women’s Hospital and professor of medicine at Harvard Medical School, and Phillip Greenland, senior editor of JAMA, professor of preventive medicine-epidemiology at Northwestern University, analyzed the latest studies on the prescribing aspirin for cardiovascular events.

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The issue is a complex one because aspirin has valuable therapeutic effects in reducing the risk of arterial vascular thrombotic events, such as myocardial infarction and stroke, the authors note. “However, this action of aspirin also increases the risk of bleeding, leading to its most troubling adverse effects: serious gastrointestinal bleeding and hemorrhagic stroke,” the authors wrote.

In reviewing pooled data from 200 trials among patients with known vascular disease, aspirin was shown to have long-term benefits in preventing major vascular events.

“These trials demonstrated that among those with known vascular disease there is net benefit, reducing the risk of major vascular events by more than 20 percent, exceeding the modest bleeding risks when aspirin is taken at a low dose daily,” the authors wrote.

On the other hand, theresults of the Japanese Primary Prevention Project (JPPP), also published in the November 17 JAMA, add to the growing body of evidence in determining in which situations aspirin should be prescribed as a preventive tool. The clinical trial studied the effect of once-daily, low-dose (100 mg), enteric-coated aspirin compared with no aspirin for preventing atherosclerotic events in 14,658 Japanese patients aged 60 years or older with hypertension, dyslipidemia, or diabetes.

However, the study was stopped short of its planned 6.5 years, according to the authors, due to futility. “After a median follow-up of five years, there was no significant difference in the rate of the composite primary end point of total number of major atherosclerotic events (nonfatal myocardial infarction, nonfatal stroke, CVD death)…” they wrote.

“There were reductions in pre-specified secondary end points of myocardial infarction and transient ischemic attack, but increased risk of serious bleeding events. These results are consistent with those of other primary prevention trials, except that in JPPP the overall risk of intracranial hemorrhage appeared higher in the studied Asian population than in Western populations. In fact, in this population, there were more fatal and nonfatal hemorrhagic strokes than myocardial infarctions,” the authors added.

After reviewing the JPPP study and others, the authors determined that “aspirin is indicated for patients at high short-term risk due to an acute vascular event and those undergoing certain vascular procedures.” On the other hand, patients with a very low risk of vascular events should not take aspirin for prevention of vascular events, even at a low dosage.