Blog | Wednesday, January 11, 2012

QD: News Every Day--Rethink the daily aspirin for those without cardiovascular risk factors

It's time to rethink the daily aspirin for heart disease for patients without known risk factors, researchers concluded. It leads to higher nontrivial bleeding risks, while offering modest benefits on nonfatal myocardial infarctions (MI) and cardiovascular disease (CVD), with no significant benefits to cancer mortality.

"The findings reported herein do not suggest a protective role for aspirin against cancer mortality in people at low-to-moderate risk for CVD events," the authors wrote in results that appeared in the Jan. 9 Archives of Internal Medicine.

"Available data also suggest that the principal cardiovascular effect of aspirin in primary prevention is on nonfatal MI with no real benefit with regard to fatal MI, stroke, or CVD death," the authors continued. "Even these benefits are considerably offset by an elevated risk of bleeding (NNT [number needed to treat] for nonfatal MI of 162 vs. NNH for nontrivial bleed of 73)."

So, patients and physicians should carefully consider the relative merits of daily aspirin treatment in primary prevention.

The conclusions were derived from a meta-analysis of nine randomized, placebo-controlled trials with at least 1,000 participants, including three new trials reported since 2005, when the previous recommendations were released. The studies included a total of more than 102,000 participants, mostly in Western populations and among health professionals.

Aspirin treatment reduced total CVD events by 10% (odds ratio [OR], 0.90; 95% confidence interval [CI], 0.85 to 0.96; NNT, 120). This was driven primarily by a reduction in nonfatal MI (OR, 0.80; 95% CI, 0.67-0.96; NNT, 162). There was no significant reduction in CVD death (OR, 0.99; 95% CI, 0.85 to 1.15) or cancer mortality (OR, 0.93; 95% CI, 0.84 to 1.03), and there was increased risk of nontrivial bleeding events (OR, 1.31; 95% CI, 1.14 to 1.50; number needed to harm, 73).

The effect of aspirin on nonfatal MI or total CVD events was unrelated to its average daily dose and was more pronounced in trials published before 2000 compared with more recent studies.

An editorial commented, "The data argue against the routine use of aspirin for primary prevention of CVD for individuals at low absolute risk of CVD. As the current guidelines recommend, it is reasonable to consider using aspirin for primary prevention in higher-risk individuals without known CVD (above 1% CVD event rate per year) if they are deemed to have a greater benefit to risk ratio and after taking into account patient preferences."

The editorial continued, "Thanks to the Patient Protection and Affordable Care Act and the aim to prevent 1 million myocardial infarctions and strokes in the next 5 years, the Centers for Medicare & Medicaid Services has now expanded coverage of CVD prevention to include intensive behavioral counseling in addition to evaluating the individual benefit-risk ratio for aspirin use in primary prevention."