What are the latest recommendations on the use of aspirin in the primary prevention of heart (cardiovascular) disease?
In 2016, the U.S. Preventive Services Task Force (USPSTF) has come up with slightly modified recommendations for the primary prevention of cardiovascular disease using aspirin. Based on their review of the published data:
- They encourage the use of aspirin in adults aged 50 to 59 years with a high risk of cardiovascular disease, are not at increased risk for bleeding, have a life expectancy of at least 10 years, and are willing to take low-dose aspirin daily for at least 10 years.
- Adults who are 60 to 69 and have high risk of cardiovascular disease may receive daily aspirin based on individual circumstances. According to the recommendations, persons who are not at increased risk for bleeding, have a life expectancy of at least 10 years, and are willing to take low-dose aspirin daily for at least 10 years are more likely to benefit. Persons who place a higher value on the potential benefits than the potential harms may choose to initiate low-dose aspirin.
- In individuals younger than 50 years of age and older than 70 years of age, the data is insufficient to recommend daily aspirin.
In 2014 the FDA reviewed all the evidence on the use of aspirin for primary prevention and did not find sufficient evidence for use of aspirin for primary prevention.
What dosage of aspirin should I take to prevent and treat heart attacks and strokes?
An ideal dose of aspirin is one that maximizes its benefits but minimizes side effects. However, the ideal dose of aspirin for primary or secondary prevention of ischemic strokes and heart attacks has not been established firmly.
- In situations where an immediate antiplatelet effect is needed (for example, in the treatment of acute heart attacks, ischemic strokes, and unstable angina) aspirin at moderate doses (160–325 mg/day) will produce rapid and immediate antiplatelet effects. In the ISIS-2 trial, a dose of 160 mg/day given within 24 hours of the onset of symptoms of heart attack was shown to decrease deaths due to heart attacks by 23%. Therefore, this is the dose recommended for acute heart attacks and unstable angina.
- At lower doses, such as 75 mg/d, the antiplatelet effect of aspirin can be achieved in several days instead of minutes. Since the risk of serious bleeding from aspirin is lower at lower doses, 75 mg/d is an appropriate dose for long-term primary and secondary prevention. Even though aspirin at doses as low as 40 mg/d has been shown to have anti-platelet effects, there is insufficient and inconclusive data to show that such low doses are effective in preventing heart attacks and ischemic strokes.
There also is no evidence that higher doses of aspirin, such as 1000 mg/day or higher, is more effective than lower doses. Some studies even suggest that higher doses may not be as effective as lower doses. Since the side effects of aspirin are more frequent with higher doses, doctors generally do not recommend higher doses for long-term use.
How effective is aspirin for preventing heart attacks among healthy people?
Long-term, low dose aspirin (75-160 mg/d) infrequently causes serious side effects; therefore, among people with advanced atherosclerosis (people who already have heart attacks and strokes, patients with angina or TIAs, and patients who need PTCA and coronary artery bypass surgery. The benefits of low dose aspirin usually outweigh the risks of long-term aspirin (discussed in this article).
Unlike the treatment of patients with advanced atherosclerosis, aspirin use among healthy subjects (for example, individuals with no prior heart attacks or strokes) is more controversial. In the U.S. Physicians' Health Study (a study comparing 325 mg of aspirin every other day to placebo among more than 20,000 healthy male doctors), there were fewer heart attacks among aspirin users as compared to placebo users. However, the overall rate of death from heart disease was no different between aspirin users and men on placebo. Furthermore, there is insufficient data to evaluate the benefit of aspirin among healthy women.
Therefore, the potential benefits of long-term aspirin in healthy subjects may not justify the risks of serious side effects of aspirin, including bleeding from ulcers and blood vessels in the brain. Healthy individuals should discuss long-term therapy with aspirin with their doctors before they start taking aspirin.
Who should take aspirin to prevent and treat heart attacks and strokes?
Even though aspirin is available without a doctor's prescription and has been used safely for many years by patients for fever and pain, patients should NOT take aspirin on a long-term basis without consulting with their doctor.
Aspirin prevents blood clots from forming inside arteries affected by atherosclerosis, but aspirin does not prevent atherosclerosis. Other measures (losing excess weight, controlling high blood pressure and diabetes, lowering LDL cholesterol, increasing HDL cholesterol, and stopping cigarette smoking) are necessary to prevent atherosclerosis.
Most doctors now recommend low doses of aspirin long-term for patients with advanced atherosclerosis for secondary prevention purposes. Such patients include those with:
- Prior heart attacks
- Prior strokes
- Exertional and unstable angina
- TIAs (transient ischemic attack, mini-stroke)
- Vascular procedures such as PTCA and CABG
People who have not had a heart attack or stroke but have a high risk for developing a heart attack or stroke should also receive long-term low dose aspirin. For example, the American Diabetes Association recommends that people 50 years of age or older with type 1 or type 2 diabetes who have a high risk for heart attacks or strokes because of hypertension, smoking, a family history of stroke or heart attacks, or abnormal lipid levels should receive aspirin daily. Adults age 50 to 59 with a high risk of cardiovascular disease may also be considered for low dose aspirin treatment.
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