Aspirin and cardiovascular disease

Full text extract from NHS Evidence:  Sept 2011

Overview: Aspirin is one of the most used medicines. It has long been a major analgesic and antipyretic, and now is widely used in lower doses as an antiplatelet agent helping to  reduce heart disease and strokes.

Research has shown aspirin to be effective in decreasing cardiovascular morbidity and mortality in patients with clinical evidence of cardiovascular disease (BMJ Clin Res ed. 2002 Jan 12;324(7329):71-86 and  Berger JS et al, Am J Med. 2008 Jan;121(1):43-9). However, there is ongoing debate about the role of aspirin in the prevention of cardiovascular disease for people without the condition. 

Current advice: In the UK low dose aspirin (75mg daily) is licensed for prevention of thrombotic cerebrovascular or cardiovascular disease only in those who already have vascular disease. It is not licensed for primary prevention.

There is evidence to suggest that aspirin should not be recommended for the primary prevention of cardiovascular events in people with diabetes (De Berardis G. et al, BMJ 2009; 339:b4531). Similarly, a Cochrane Review concluded that aspirin cannot be recommended for primary prevention in patients with elevated blood pressure because the magnitude of benefit is negated by a harm of similar magnitude (Lip GY et al, Cochrane Database Syst Rev. 2004;(3):CD003186).

It is advised to take aspirin after food. The most common adverse affect is indigestion, and so aspirin should not be used (except on medical advice) in someone who has a peptic ulcer or who has had one in the past. Aspirin must not be used by anyone who has a bleeding disorder, or who is taking blood thinning drugs (anticoagulants).

New evidence: A meta-analysis (Berger JS et al: Am Heart J. 2011 Jul;162(1):115-124) examined the effect of aspirin on the prevention of cardiovascular events in patients without clinical cardiovascular disease.

The study included 9 trials involving 102,621 people without clinical evidence of cardiovascular disease. Results found that for every 1,000 people treated with aspirin over a 5 year period, aspirin would prevent 2.9 major cardiovascular events and cause 2.8 major bleeds.

The evidence provides only modest support for a benefit of aspirin in people without clinical cardiovascular disease, which is offset by its risk.

Commentary: “It is reassuring to see further evidence to support current UK policy, i.e. aspirin is not indicated for the primary prevention of cardiovascular disease.

“This meta-analysis also supports the recent verdict by the epidemiologists, pharmacologists and clinicians who are now conducting international PolyPill trials. They all opted for a combination of statin and blood pressure lowering therapy. However, most explicitly excluded aspirin.

“Secondary prevention is a very different matter. Aspirin should be seriously considered for every patient with coronary heart disease, stroke or peripheral vascular disease. Subsequent fatal and non fatal events are reduced by at least 15%.

“Finally, we should always aim to target smoking (treating the causes rather than the consequences). Aspirin basically inhibits blood clotting. Whereas smoking substantially increases thrombotic risk. Every clinician should therefore be investing time to urge cessation in every individual smoker they encounter, as well as supporting tobacco control policies nationally and globally.”  Simon Capewell, professor of clinical epidemiology, University of Liverpool.

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