Aspirin's Risks Outweigh Benefits in Preventing Heart Disease

UK researchers analyzed nine studies involving more than 100,000 patients and found that taking a daily aspirin to prevent heart disease increased the risk of serious stomach bleeds by 30% — but only decreased the risk of heart attacks by 10%. In other words, aspirin did a lot more harm than good. The researchers' conclusion: routine use of aspirin to prevent heart attacks isn't justified.

"The major reason to give aspirin is to prevent heart attacks and strokes, and in healthy people this benefit is outweighed by the risk of bleeding," the study's lead author told the media.

Here's the abstract of the study, from the US National Library of Medicine:

Study Abstract

Background

The net benefit of aspirin in prevention of CVD and nonvascular events remains unclear. Our objective was to assess the impact (and safety) of aspirin on vascular and nonvascular outcomes in primary prevention.

Data Sources

MEDLINE, Cochrane Library of Clinical Trials (up to June 2011) and unpublished trial data from investigators.

Study Selection

Nine randomized placebo-controlled trials with at least 1000 participants each, reporting on cardiovascular disease (CVD), nonvascular outcomes, or death were included.

Data Extraction

Three authors abstracted data. Study-specific odds ratios (ORs) were combined using random-effects meta-analysis. Risks vs benefits were evaluated by comparing CVD risk reductions with increases in bleeding.

Results

During a mean (SD) follow-up of 6.0 (2.1) years involving over 100 000 participants, aspirin therapy reduced total CVD events by 10% (OR, 0.90; 95% CI, 0.85-0.96; number needed to treat, 120), driven primarily by reduction in nonfatal MI (OR, 0.80; 95% CI, 0.67-0.96; number needed to treat, 162). There was no significant reduction in CVD death (OR, 0.99; 95% CI, 0.85-1.15) or cancer mortality (OR, 0.93; 95% CI, 0.84-1.03), and there was increased risk of nontrivial bleeding events (OR, 1.31; 95% CI, 1.14-1.50; number needed to harm, 73). Significant heterogeneity was observed for coronary heart disease and bleeding outcomes, which could not be accounted for by major demographic or participant characteristics.

Conclusions

Despite important reductions in nonfatal MI, aspirin prophylaxis in people without prior CVD does not lead to reductions in either cardiovascular death or cancer mortality. Because the benefits are further offset by clinically important bleeding events, routine use of aspirin for primary prevention is not warranted and treatment decisions need to be considered on a case-by-case basis.

Resources

"Effect of Aspirin on Vascular and Nonvascular Outcomes: Meta-analysis of Randomized Controlled Trials." Seshasai SR, Wijesuriya S, et al. Arch Intern Med. 2012 Jan 9. [Epub ahead of print]