Low dose aspirin is now recommended to prevent heart disease and cancer.
Despite the remarkable advances in medicine over the past 20 years, cardiovascular disease and cancer will still kill half of us. Beyond the deaths, millions survive heart attacks, strokes and cancer, but many are left with disability and a reduced quality of life. While lifestyle changes can improve our odds of avoiding these diseases, they do not eliminate our risk. Finding ways to medically prevent these diseases before they occur, a term called “primary prevention”, is a holy grail in medicine. Primary prevention can be a tough sell, personally and medically. It means taking medicine (which may cause side effects) when you’re well, with the hope of preventing a disease before it occurs.
The US Preventative Services Task Force (USPSTF) released draft guidelines on the primary prevention of cardiovascular disease and colorectal cancer last week. The USPSTF is now recommending daily aspirin in some age groups who have at least a 10% risk of cardiovascular disease in the next 10 years. This isn’t the first guideline that’s recommended aspirin for primary prevention of cardiovascular disease, but it is the first major guideline to endorse aspirin to prevent colorectal cancer. Given these recommendations will apply to millions of people, they have attracted considerable controversy. Is this strategy going to reduce deaths and disability? Or are we about to start “medicalizing” healthy people inappropriately? (more…)
A new study published in JAMA sheds further light on a controversial question – whether or not to prescribe low-dose aspirin (81-100mg) for the primary prevention of vascular disease (strokes and heart attacks).
Primary prevention means preventing a negative medical outcome prior to the onset of disease, in this case preventing the first heart attack or stroke. Secondary prevention refers to treatments given to patients who have already had their first heart attack or stroke in order to reduce the risk of subsequent events.
The evidence strongly supports the efficacy of aspirin for the secondary prevention of both heart attacks and strokes. Aspirin has two effects which likely contribute to this protective effect. First, aspirin is an anti-platelet agent – it reduces the stickiness of platelets, which are cell fragments in the blood that clump together to stop bleeding. They can also clump together around an ulcerated cholesterol plaque on an artery, forming a thrombus, resulting in blockage or embolus (the clot traveling downstream) and causing either a heart attack or stroke.
Other anti-platelet agents, such as clopidogrel, are also effective in preventing stroke and heart attack.
Of course, platelets exist for a reason, and blocking their action increases the risk of bleeding or can make bleeding worse when it occurs. Therefore determining the optimal dose and target population are important to maximize the benefit of aspirin or other anti-platelet agent while minimizing the bleeding risk. (more…)
A new review published in the BMJ once again opens the question of the risks vs benefits of daily aspirin as a prevention for heart attacks and strokes. The reviewers looked at nine randomized trials involving over 100,000 patients and found that aspirin is effective in reducing heart attacks and strokes, but also increases the risk of gastrointestinal bleeding and that in some patients this risk outweighs the benefit.
This is an old and enduring controversy, and one with significant public health ramifications. Aspirin is an anti-platelet agent – it inhibits platelets, the cell fragments in the blood that are the first line against bleeding, from aggregating (clumping together). Platelets aggregate in order to quickly stop bleeding from damaged veins or arteries. But they can also aggregate around cholesterol plaques in arteries, causing a large thrombus (blood clot) that can block off the artery, or that can break off and lodge in a downstream artery (an embolus) and cause a stroke or heart attack.
By inhibiting platelet aggregation daily aspirin reduces the risk of forming a thrombus or embolus, and thereby reduces the risk of heart attack or stroke. Of course, the real story is always more complex than our straightforward explanations. There is some research to suggest that the anti-inflammatory effects of aspirin may also be important to their role in reducing vascular risk. The relative contribution of anti-platelet and anti-inflammatory effects have not been fully teased out. Further, the anti-inflammatory effects of daily aspirin may have non-vascular benefits, like reducing the risk of some cancers.