Study raises questions about aspirin as primary prevention for CVD

Aspirin prophylaxis in people without prior cardiovascular disease (CVD) does not appear to reduce cardiovascular death or cancer mortality, according to the results of a meta-analysis published online January 9 in the Archives of Internal Medicine.

The results did show, however, that aspirin was associated with reductions in nonfatal myocardial infarction (MI).

Sreenivasa Rao Kondapally Seshasai, MD, from St. George's University of London, and colleagues sought to assess the impact and safety of aspirin on vascular and nonvascular outcomes in primary prevention and to update previous findings. They reviewed data from nine randomized placebo-controlled trials with at least 1,000 participants each, which reported on CVD, nonvascular outcomes, or death.

“Current guidelines for use of aspirin in primary prevention of CVD are based on information from trials published up to 2005, since when at least 3 additional studies have been reported,” the authors wrote. “Emerging data from primary and secondary prevention trials also suggest significant reductions in cancer mortality in people receiving aspirin prophylaxis, stimulating discussions for more widespread use of this agent among healthy individuals.”

In this update synthesizing previous studies, the investigators evaluated risks versus benefits by comparing CVD risk reductions with increases in bleeding.

They reported that aspirin treatment reduced total CVD events by 10% (OR=0.90; 95% CI, 0.85-0.96; number needed to treat, 120) over a mean follow-up of 6.0 years for 102,621 patients. Results were driven primarily by a reduction in nonfatal MI.

The authors found no evidence that aspirin had a protective role against cancer mortality in people at low-to-moderate risk for CVD events. However, they did note an increased risk of nontrivial bleeding events (30%).

“This meta-analysis provides the largest evidence to date regarding the wider effects of aspirin treatment in primary prevention and contextualizes the relevance of aspirin prophylaxis by comparing CVD risk reduction against concomitant elevation in risk of bleeding,” the authors wrote.

In a commentary accompanying the article, Samia Mora, MD, MHS, noted that the benefit to risk ratio for aspirin therapy among patients with no prior CVD be carefully weighed because aspirin increases the risk of bleeding (GI bleeding and, more rarely, hemorrhagic stroke).

“To date, the data argue against the routine use of aspirin for primary prevention of CVD for individuals at low absolute risk of CVD,” Dr Mora wrote.