An Aspirin a day keeps the heart attacks away? Maybe not.
Individuals with no history of heart disease who pop the little white pills daily to ward off heart attacks and strokes could be doing themselves more harm than good, say editors at the Drug and Therapeutics Bulletin.
Many doctors prescribe the drug to patients who have suffered a heart attack or stroke because it has been proven to block the formation of dangerous blood clots, which can cause heart attacks or strokes. Treating someone who has already suffered a cardiovascular event is known as "secondary prevention" while treatment before such an event is called "primary prevention."
An article today in Drug and Therapeutics Bulletin says the benefits of ASA as primary prevention without previous heart trouble may be outweighed by risks of bleeding.
"The evidence accumulating suggests that when you look for hard evidence in primary prevention, it seems to be flimsy to non-existent," said editor Ike Iheanacho.
He reviewed several studies on Aspirin - known by the generic term acetylsalicylic acid (ASA) - which suggest the drug did little to protect subjects who had no history of heart attack or stroke from heart disease - even those with diabetes or elevated pressure, who are considered to be at higher risk.
Dr. Iheanacho points to a study published in the May 30 issue of the medical journal The Lancet, in which researchers found that taking a daily low dose of ASA only reduced the occurrence of heart attack, stroke and vascular death in test subjects by 0.07 per cent, compared to those who didn't take it. After following test subjects for an average of 6.4 years, the reviewers found that taking Aspirin prevented three cardiovascular events for 1,000 women and four for every 1,000 men.
In the Lancet study as well as two others done exclusively with patient of Type 1 and Type 2 diabetes - considered at high risk for heart disease - those who took Aspirin daily had the same rates of death due to coronary heart disease and stroke as did those who didn't take it.
Dr. Iheanacho said in addition to the minimal benefits of ASA in preventing cardiovascular events, one must also consider the risk of bleeding.
Aspirin affects platelets in the blood and can cause bleeding and bruising when taken regularly. In the Lancet study, researchers found that taking Aspirin increased patients' risk of having major gastrointestinal bleeding by 0.03 per cent per year compared to those who didn't take it. Subjects also suffered 2.5 major bleeding events for every 1,000 women and three major bleeding events for every 1,000 men. The authors of the Lancet study said this offset the benefits of taking ASA.
"Some people might say, 'I'm more worried about having a heart attack or stroke than I am about a bleed.' But bleeding can be fatal," said Dr. Iheanacho. "Although it's a small risk, it's in the same ball park as any benefit you'd get from taking it."
He said he still recommends ASA for patients who have a history of heart disease because the benefits are significant, but for those who haven't had a heart attack or stroke, the "risk is much, much greater."
Many global bodies, such as Britain's National Institute for Health and Clinical Excellence, advise those who are considered at risk for heart disease take 75 milligrams of ASA daily as a form of primary prevention, despite these recent studies that cast doubt on its effectiveness for primary prevention. In Canada, the Heart and Stroke Foundation takes a more cautious approach and recommends individuals seek advice from their doctors before making Aspirin part of their daily routine.
Dr. Beth Abramson, a Toronto cardiologist and spokeswoman for the Heart and Stroke Foundation, said she's concerned by the over-the-counter availability of Aspirin, because many individuals self-prescribe the drug without needing it.
She said she prescribes low-dose Aspirin to all her patients who have previously suffered a heart attack or stroke, but for those who haven't, she does an individual assessment first and considers their age, blood pressure, smoking status, cholesterol and family history of heart disease to determine whether or not they should take the medication.
"In general, even though there's little conclusive evidence, I recommend it for people who are moderate to high risk," she said.
But there's a far better form of primary prevention out there.
"It's probably better for us to take a placebo pill," she said. "Go out for a walk, eat healthier, attempt challenging lifestyle changes instead of looking for a quick fix with a pill like Aspirin."