Don't Stop Your Aspirin Without Good Reason!

Summarized by Robert W. Griffith, MD
November 7, 2005

Introduction

Many older people take a small daily dose of aspirin to prevent thrombosis in their blood vessels - principally the coronary and cerebral arteries, and the leg veins. That's because aspirin (acetylsalicylic acid) is an anti-platelet agent, due to its inhibition of a platelet enzyme, thromboxane A2; its effect on platelets continues for the life of the platelet - as long as 120 days. Of course, the main action of aspirin is inhibition of prostacyclin, which gives it its anti-inflammatory properties. But prostacyclin also inhibits platelet clumping, which is a feature of thrombosis.

Sometimes people stop taking their regular aspirin: before planned surgery, if they have a hemorrhage, or if it interacts with another drug. In such cases, a rebound effect has been occasionally reported. Now a study from Switzerland has been done to see if stopping aspirin is a risk factor for ischemic stroke ¹. It's been reported in the Archives of Neurology, and we summarize it here.

What was done

The hospital records of all patients admitted to the stroke unit of a Swiss hospital over a 2-year period were examined. There were 309 patients who had been taking long-term aspirin in the period before they had a stroke or a transient ischemic attack (TIA, sometimes called a mini-stroke). An equal number of outpatients who had a history of a stroke, but who had not had a stroke or a TIA in the previous 6 months, and who were taking long-term aspirin, were selected as controls; they were carefully matched as regards age, sex, and treatment to the first group.

Information that was obtained for all 618 patients in the study comprised: sex, age, risk factors, cause of stroke, type and dose of antiplatelet therapy, blood pressure, presence of diabetes, smoking history, and cholesterol level.

The average frequency of aspirin discontinuation (for any reason) during the 4 weeks before the stroke or TIA, or before the interview for the control group, was compared.

What was found

The average age of the subjects was 70; two-thirds of them were men, and the majority had high blood pressure and a high cholesterol level. One in five was diabetic.

Thirteen of the study group (4.2%) had stopped taking aspirin in the 4 weeks before their stroke or TIA. In the control group, only 4 outpatients (1.3%) had stopped aspirin in the 4 weeks before their interview.

The difference in frequency between the two groups was statistically significant, i.e. it did not occur by chance alone.

In 7 of the 17 patients who stopped aspirin did so on the advice of their physician, either because of planned surgery or because the physician didn't think it was necessary for them to continue. In 5 of the 17, the patients decided themselves to discontinue, because of bleeding complications. And in the rest, stopping was due to negligence or dementia.

What these findings mean

This study clearly demonstrates a rebound effect after aspirin withdrawal. Stopping long-term aspirin use was associated with a stroke or TIA more than three times as often in patients at increased risk of a stroke than in those who hadn't had a stoke in the previous 6 months.

Supporting this concept, other workers have reported a 2% to 4% incidence of coronary thrombosis or acute angina within after stopping aspirin ². These findings have led to recommendations that aspirin not be stopped before most vascular, dermatologic, and ophthalmic surgical procedures.

There are three things an older patient on aspirin therapy can, and should, do. First, they must make sure that they don't neglect to take their aspirin for more than a day or so at a time. Second, if their doctor recommends stopping aspirin, they should ask why, and make sure there's a good reason before they follow her/his advice. Third, if someone is worried about a bleeding problem, they should go to their doctor, and not just stop taking aspirin on their own.

Source

• Effect of discontinuing aspirin therapy on the risk of brain ischemic stroke. MAB. Maulaz , BDC. Bezerra , MP. Michel , BJ. Bogousslavsky , Arch Neurol, 2005, vol. 62, pp. 1217--1220

Footnotes
1. Ischemic stroke is the most common type of stroke - accounting for almost 80% of all strokes - and is caused by a clot or other blockage within an artery supplying brain tissue.

Related Links
Aspirin withdrawal risky for heart patients
Best not to stop aspirin before surgery
An Aspirin a Day Keeps the Doctor Away, Doesn't it?

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