Aspirin for Primary Prevention: What Should We Tell Patients?

Internal Medicine News Link

There’s little controversy surrounding the use of aspirin for the prevention of cardiovascular events in patients with established disease. By contrast, there’s far more smoke than light regarding the issue of aspirin for primary prevention. We all commonly face the proverbial “handle-on-the-doorknob” question, “Should I be taking aspirin?” from patients without established cardiovascular disease. Such interactions tax us to recall our most recently-attended CME meeting to try and remember what the general mood of clinicians was on this issue.

A recent large meta-analysis (Arch Intern Med.2012;Jan 9 [doi:10.1001/archinternmed.2011.626]) will inform these conversations in the year ahead. In this study, investigators conducted a meta-analysis of studies that had at least one year of follow-up and at least 1,000 participants. Nine trials involving a total of more than 100,000 patients were included. Aspirin was associated with a reduction in cardiovascular (CVD) events attributable primarily to the nonfatal MI. No effect of aspirin was observed on fatal MI, stroke, CVD death or cancer mortality. A 70% increase in bleeding events was observed with a 30% increase in the risk of clinically significant bleeding events, defined as fatal bleeding from any site, cerebrovascular or retinal bleeding, bleeding from hollow viscus, bleeding requiring hospitalization and/or transfusion, or study-defined major bleeding regardless of source. The number needed to treat for nonfatal MI was 162 compared to the number needed to harm for nontrivial bleed of 73.

The data suggest that for every two patients to whom we recommend aspirin to prevent a nonfatal MI we will have two clinically significant bleeding events. Perhaps the authors are correct in suggesting that aspirin may add little extra value to CVD risk reduction efforts that aggressively target lipid levels, blood pressure, and tobacco use behaviors. But we can’t ignore the aspirin question because patients want to know what to do and, commonly, the justification for it. In patients at low risk for CVD events, aspirin prophylaxis may make them bleed. But let us not throw the baby out with the bathwater because among higher risk patients, the data are strong that aspirin may prevent a heart attack and some patients may place high value on this prevention. For those in the middle, perhaps creative aspirin dosing, such as every-other-day, could be explored.