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Menopause Live - IMS Updates
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Date of release: 20 February, 2012

Aspirin revolution?


The objective of a recently published meta-analysis by Seshasai and colleagues [1] was to assess the impact (and safety) of aspirin on vascular and non-vascular outcomes in primary prevention. Nine randomized, placebo-controlled trials with at least 1000 participants each, reporting on cardiovascular disease (CVD), non-vascular outcomes, or death were included. During a mean (standard deviation) follow-up of 6.0 (2.1) years involving over 100,000 participants, aspirin treatment reduced total CVD events by 10% (odds ratio (OR) 0.90; 95% confidence interval (CI) 0.85–0.96; number needed to treat = 120), driven primarily by reduction in non-fatal myocardial infarction (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 non-trivial bleeding events (OR1.31; 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. Despite important reductions in non-fatal myocardial infarction, 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.

Comment

Any long-time physician has witnessed changes in therapeutic algorithms and guidelines related to prevention of common diseases. Although we were exposed to data on the risks of aspirin therapy in primary prevention of cardiovascular disease, the traditional prescription of aspirin to healthy people still prevails. But now this new meta-analysis of nine major studies (100,000 participants) has indicated that the riskbenefit balance does not favor the use of aspirin [1]. In short, the number needed to treat in order to save one cardiovascular event is twice as much as the number needed to harm, to cause non-trivial bleeding. Although a modest favorable balance was recorded for non-fatal myocardial infarction and total CVD events, the outcome of giving placebo equalled that of aspirin in the categories of fatal myocardial infarction, stroke, cardiovascular death and cancer mortality. Interestingly, and in contrast to previous meta-analyses, no gender differences were detected [2]: aspirin therapy in women was associated with a significant 17% reduction in stroke, which was a reflection of reduced rates of ischemic stroke (OR 0.76; 95% CI 0.630.93; p= 0.008), but there was no significant effect on myocardial infarction or cardiovascular mortality. Among men, aspirin therapy was associated with a significant 32% reduction in myocardial infarction (OR 0.68; 95%CI 0.540.86; p= 0.001); however, there was no significant effect on stroke or cardiovascular mortality. The investigators of the current meta-analysis, being aware of the potential dramatic impact of their results, were cautious with interpretation of the data and put forward the following points: (1) It may be argued that events such as myocardial infarction are potentially more serious compared with bleeding, and therefore both patients and physicians should carefully consider the relative merits of daily aspirin treatment in primary prevention. (2) The results suggest an increased risk of non-trivial bleeding in individuals receiving daily (vs. alternate day) aspirin treatment. (3) A particularly unfavorable risk-to-benefit ratio was observed for individuals at lower baseline CVD risk (i.e. less than 1% chance for an event per year). (4) The analysis also showed that aspirin was no better than placebo for reducing non-fatal myocardial infarction events in trials published after 2000, which may be ascribed to better treatments for CVD or underlying risk factors. This decline suggests that, in contemporary primary prevention settings, aspirin may add little extra value to other CVD risk reduction strategies that target lipid levels, blood pressure, and smoking, especially in low-risk individuals. (5) By the end of the day, the decision whether or not to prescribe aspirin should be individual, and should consider the general health and the risk profile of any particular patient.

Comentario

Amos Pines
Department of Medicine T, Ichilov Hospital, Tel-Aviv, Israel

    References

  1. Seshasai SR, Wijesuriya S, Sivakumaran R, et al. Effect of aspirin on vascular and nonvascular outcomes: meta-analysis of randomized controlled trials. Arch Intern Med 2012 Jan 9. Epub ahead of print
    http://www.ncbi.nlm.nih.gov/pubmed/22231610

  2. Berger JS, Roncaglioni MC, Avanzini F, et al. Aspirin for the primary prevention of cardiovascular events in women and men: a sex-specific meta-analysis of randomized controlled trials. JAMA 2006;295:306-13
    http://www.ncbi.nlm.nih.gov/pubmed/16418466