Monday, January 28, 2019

An aspirin a day keeps which doctor away?

Should you take low dose aspirin every day? If you have coronary disease and have not had major bleeding issues, you can stop reading and look for a funny cat video. The easy answer is yes. The rest of you can read on.
Aspirin, or at least its forefathers, has been around forever. The ancient Egyptians used willow bark for aches and pains and Hippocrates prescribed willow leaves and bark for fever and pain. The active ingredient in the willow was salicylic acid, isolated by a French pharmacist in 1829. The aspirin we know, acetylsalicylic acid, was developed by Bayer Pharmaceuticals in the late 1890’s in Germany and was widely available over the counter beginning about 1915.
While aspirin has many actions, the one of most importance to its use for cardiovascular disease is its ability to prevent platelets from sticking together. Platelets are small circulating cells that plug up holes in blood vessels and prevent us from bleeding excessively. Platelets that clump together can block small arteries and are a major culprit in causing heart attacks and strokes. Logically, then, you would expect aspirin taken regularly to reduce the risk of heart attacks and strokes and increase the risk of bleeding, and this is a situation in which what seems logical is also true.
One of the first large-scale trials on which we now depend to inform medical decision-making looked at adding aspirin to the medications given patients presenting to hospitals with suspected heart attacks. This trial, called ISIS-2 was reported back in 1988 and showed that aspirin did reduce the rate of death and vascular complications when given over the short-term, and that it seemed to have few serious side effects given this way. Over the subsequent decades, numerous trials of aspirin use in patients with a variety of forms of heart disease were conducted, and the “big picture” showed that daily use of low-dose aspirin in coronary patients cut the rate of death, heart attack and stroke combined by about 22% relative to non-use. In absolute terms, if 1000 patients took aspirin and 1000 did not, the aspirin users suffered 25 fewer major cardiovascular events – at a cost of 4 major bleeding events.
What about preventing heart attacks in patients without known coronary disease? Here the benefits would be expected to be smaller, but would apply to many more people. Numerous trials have been done, and a recent review published in JAMA in January 2019 summarized the available data, looking at 13 trials that included over 164,000 participants. The bottom line was that daily aspirin use reduced the rate of major cardiovascular events from 61.4 per 10,000 person-years to 57.1 – a modest but statistically valid reduction. The price paid was an increase in major bleeding events from 16.4 per 10,000 person-years to 23.1. So, for every heart attack or stroke prevented there were almost two major bleeds.
I should note that there is tantalizing but not conclusive evidence that daily aspirin use reduces the risk of some cancers, notably colon cancer, when taken over many years. The cancers that do develop in aspirin users may be more aggressive, and there is as yet no data on overall life extension by aspirin.
Bottom line: personalize. If you have risk factors for coronary disease and no history of ulcers or other bleeding issues, I would seriously consider taking low dose aspirin daily. If your coronary risk is low, it is probably not a good idea. As the TV commercials always say, talk to your doctor.

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