Aspirin. Cheap. Familiar. Should you take it?
This week new guidelines about prevention were released – and there was a focus on aspirin. SI have heard some confusion about this common medication – with many people wondering what to do.
That made me think that it’s time for a quick briefing on where we stand on aspirin.
In some form, this medication has been around for millennia. The Egyptians used bark from a tree that had some of the ingredients that are now in the aspirin pill. The science behind aspirin is extraordinary – and it can quiet inflammation, reduce pain, and soften fevers. And they can inhibit the function of platelets, which contribute to blood clots.
Starting a couple of decades ago, researchers showed that aspirin could reduce the risk of heart disease – and the risk of dying for those during a heart attack. The findings for those with a heart attack are particularly striking. Treatment with a puny aspirin produced about a 20% reduction in the risk of dying within a month of a heart attack. Aspirin rivaled our most powerful clot-busting drugs for its ability to promote survival. And remarkably, that survival advantage continued for years and years. No expert I know disputes this benefit – and our guidelines and textbooks still tout the importance of aspirin in the treatment of patients with heart attacks.
Aspirin, it turns out, also has benefits for people who have had stents – or undergone bypass surgery. These studies also show that the benefits far outweigh the risks – and most people will want to opt for taking aspirin to reduce their chances of the stents or the bypass grafts failing – or of blood clots forming in other arteries of the heart.
Of note, aspirin treatment is not risk-free. Aspirin inhibits platelets, which are constituents of the blood involved in clotting. Although many people tolerate aspirin well, there is an increased risk of bleeding. Often the bleeding causes little trouble and resolves quickly – but sometimes the bleeding can be life-threatening.
So where is the controversy over aspirin? The area of medicine where the recommendations about aspirin are in flux is for people who have not had evidence of cardiovascular disease. The use of aspirin in this situation is called primary prevention – and it is called that because it is intended to prevent the first instance of heart disease.
The challenge of using medications for primary prevention is that the benefit tends to be smaller than for people with established heart disease – and farther in the future. To be worth treating someone with medication for many years for future prevention, it has to be very effective and very safe – or the balance of risks and benefits may not tip strongly toward advantage.
If you live in an earthquake-prone area, then it would seem very worthwhile to invest in structures that can withstand the force of the earth moving. Despite the inconvenience, cost, aesthetics of such structures might make it something people would want. But for those who live in an area that has never experienced an earthquake – the risk is lower – and the investment in such structures may seem less attractive – even though it is still possible that they could have an earthquake. And borrowing money, for example, to reduce the risk of something that may never happen, may not be worth it. It all depends on the risk of the earthquake.
So here is what we know about aspirin for people that have not experienced heart disease. The studies are not all consistent, but there is a message from them. In an analysis of all the studies, the risks and benefits were quite close. Overall, about 250 people needed to take aspirin for 10 years to prevent one adverse heart event. Meanwhile, during that time, there was about one major bleeding episode for about every 201 people treated (mainly intracranial and gastrointestinal). Overall, the increase in major bleeding incidents was slightly higher than the decrease in cardiovascular events.
This week the American College of Cardiology and the American Heart Association released new primary prevention guidelines. For those without cardiovascular disease, they demoted aspirin to something that might be reasonable (but is not being recommended) for people 40 to 70 years old and is considered something to be avoided (potentially harmful and should not be used) by those who are older than 70 years old or at increased risk of bleeding. By the way, the Europeans had already not recommended aspirin for primary prevention. And for those with other reasons to take aspirin, you should not confuse these recommendations for people without cardiovascular disease (including stroke) for those that are for people who have heart disease, heart procedures, or other reasons to take aspirin. In any case, it is important to touch base with your doctor before discontinuing any medication.
In the end, the decision about the use of aspirin for primary prevention is yours. Aspirin is available over the counter – you can buy it easily. You should ideally make the choice based on your assessment about the balance of risks and benefits and how you feel about taking pills – and that is a topic that is good for a patient-doctor discussion. The risks from the studies may not exactly apply to you. What is clear is that, on average, the evidence for benefit is not so strong and we should not be pushing aspirin for primary prevention. For most people without evidence of cardiovascular disease, less will be more – with the benefit of aspirin just not worth the risk and inconvenience – and that will be particularly true for those older than 70 years or with an increased risk of bleeding. And that fits just fine with the current evidence – and now with the new guidelines.