Abstract and Introduction
AbstractLow-dose aspirin has been shown to be effective in preventing about one-fifth of atherothrombotic vascular complications (non-fatal myocardial infarction, non-fatal stroke, or vascular death) in a meta-analysis of 16 secondary prevention trials in patients with previous myocardial infarction, stroke, or transient cerebral ischaemia. This corresponds to an absolute reduction of about 10–20 per 1000 patients in the yearly incidence of non-fatal events, and to a smaller, but still definite, reduction in vascular death. Against this benefit, the absolute increase in major extracranial bleeding complications [mostly, gastrointestinal (GI)] is 20- to 50-fold smaller, depending on age and sex. Hence, for secondary prevention, the benefits of antiplatelet therapy substantially exceed the risks. For primary prevention, the balance between vascular events avoided and major bleeds caused by aspirin is substantially uncertain because the risks without aspirin, and hence the absolute benefits of antiplatelet prophylaxis, are at least an order of magnitude lower than in secondary prevention. The aim of this article is to review the updated evidence for the efficacy and safety of low-dose aspirin in primary prevention and to discuss additional health benefits resulting from prolonged antiplatelet therapy in apparently healthy people at low average risk of vascular events.
ConclusionsFor secondary cardiovascular prevention, the net benefits of adding aspirin to other preventive measures would substantially exceed the bleeding hazards, irrespective of age and gender.[66,67] In contrast, for many people without pre-existing vascular disease, the cardiovascular benefits of adding long-term aspirin to other, safer, forms of primary prevention (e.g. statins and antihypertensive drugs) are likely to be of similar magnitude as the hazards.
 Four ongoing primary prevention trials may help assess the benefit/risk profile of low-dose aspirin in preventing multiple outcomes (including dementia and cancer) in ~50 000 participants at somewhat higher cardiovascular risk than in the earlier trials, because of diabetes mellitus (ASCEND and ACCEPT-D), advanced age (ASPREE), or a cluster of risk factors (ARRIVE).
 Hence, the currently available trial results do not seem to justify general guidelines advocating or discouraging the routine use of aspirin in all apparently healthy individuals above a moderate level of coronary risk, unless additional long-term benefits of aspirin therapy become firmly established. In the meantime, clinical judgement as well as adequate knowledge of the available data may help the doctor–patient relationship in making a personalized choice after considering the different components of a complex equation that includes the patient's preferences and values.