Key Points on low dose aspirin

Yesterday some of my more well informed and alert patients and friends drew my attention to a newspaper report of the US preventive task force’s latest recommendation about low dose aspirin. This short write up is pertaining to the same so that there is clarity in minds of people.

1.       Clotting and bleeding are opposite phenomena. Agents which prevent clotting can cause bleeding. Aspirin is one such agent.

2.       There are two groups of people for whom preventive therapy with low dose (LD) aspirin is applicable.(Low dose which is less than 100mg has been shown to have same benefits as full dose of 325 mg, but with the benefit of less bleeding.)

3.       One group is composed of those who already have evidence of arterial disease such as a heart attack, angina, angioplasty, bypass surgery, ischemic brain stroke or arterial disease of the limbs.

4.       For these people, life-long LD aspirin (or another antiplatelet drug like clopidogrel) is HIGHLY advisable because the benefit in terms of preventing another clotting event like a heart attack far outweighs the risk of bleeding in the gut or the brain-the most important risk with aspirin. This is called secondary prevention.

5.       The other group of people is composed of those who are apparently healthy and wish to prevent heart attacks or strokes in future, which is called primary prevention.

6.       Some years back, the popular notion was that LD aspirin should be given to all above 40 years to prevent a heart attack. This was not based on scientific evidence, but from observation and impression gathered from population.

7.       In the last few years came hard evidence in form of placebo controlled, randomized trials with aspirin which showed that for primary prevention, the risk of bleeding may outweigh the benefit with LD aspirin.

8.       Hence in 2019 American College of Cardiology & American Heart Association recommended that LD aspirin for PRIMARY PREVENTION is not advisable for people above age 70 or ANYONE at high bleeding risk.

9.       But they said LD aspirin MAY BE advisable for primary prevention in people between ages of 40 and 70 who are at high cardiovascular disease risk (such as people with family history of premature heart disease, people with hypertension, diabetes, high cholesterol, smokers, obese etc) and low bleeding risk, to prevent heart attacks and colorectal cancer. It may also be recommended for people who already are on LD aspirin without side effects.

10.   The current US task force’s recommendation is almost the same as the 2019 recommendation by ACC-AHA except that the upper age limit is brought down to 60 and prevention of colorectal cancer is no longer a reason for preventive therapy with LD aspirin. 

11.   These are general recommendations for the population. At the individual level, shared decision making with your cardiologist is recommended after weighing your probability of benefit against your risk of bleeding with LD aspirin.

12.   Lastly, one group of patients that is not covered by the above scientific bodies is people without any symptoms but with fatty deposits in their heart, brain or leg arteries as shown by tests like coronary artery calcium score, coronary CT angiography, doppler showing plaques in carotid arteries or BP in legs lower than that in arms.

13.   Such people (for example with coronary artery calcium score more than 100 and) at high risk may be well advised LD aspirin for prevention. Again, shared decision making with your cardiologist is advisable after discussing the risk-benefit issues.