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Can an Aspirin a Day Do More Harm Than Good?

校友推荐 May 29, 2011

Experts are re-evaluating who should swallow a daily dose。

HIGHER RISK FOR BLEEDING： Aspirin can cause bleeding in anyone, but some things put people at higher risk.

• Being male
• Being older than 60
• Taking ibuprofen and acetaminophen (Advil and Tylenol)
• Drinking alcohol (moderate to high)
• Having peptic ulcers
• Having bleeding disorders

HOW DOES ASPIRIN WORK?Why are we getting so many conflicting messages about aspirin? The answer may lie in how powerful the drug actually is.

Aspirin was first created in labs during the 19th century. The drug quickly proved to be extraordinary; its ability to relieve pain and reduce inflammation secured it a permanent place in American medicine cabinets. But that wasn’t all aspirin could do. In 1989, a major study of 22,000 doctors revealed that the drug significantly reduced the incidence of heart attacks and stroke.

Since then, further evidence of aspirin’s cardiovascular benefits has only continued to accumulate. Scientists discovered that the secret to aspirin’s powers is its effect on platelets, cell fragments that circulate in the bloodstream.

When platelets stick together, they form blood clots. That’s good news when you cut yourself—it’s what keeps you from bleeding out on the kitchen floor—but clots are also responsible for some catastrophic health problems. If these clots travel through the bloodstream and reach the heart, they can cause heart attacks; if they reach the brain, they can cause strokes.

Aspirin, as it turns out, is “one of the most effective anti-platelet drugs that we have,” says Jeffrey Berger, M.D., a cardiologist at New York University. “It basically inhibits platelet function.” By decreasing platelet activity, it can prevent these clots and, thereby, heart attacks and strokes.

Some 43 million Americans do it every day: take a tiny aspirin to help prevent heart attacks and strokes. In fact, doctors have been routinely recommending the practice to older adults for years. But recently, experts have been questioning the aspirin-a-day regimen, concerned that this everyday miracle drug can pose serious risks, including bleeding in the brain and stomach.

The aspirin-a-day controversy erupted publicly in March when a 10-year study of nearly 30,000 adults ages 50 to 75 without known heart disease found that a daily aspirin didn’t offer any discernible protection. The group taking aspirin had cardiovascular disease at the same rate as those taking a placebo. Moreover, the study—published in the Journal of the American Medical Association—reported that taking a daily aspirin (100 mg) almost doubled the risk of dangerous internal bleeding.

And last year the U.S. Preventive Services Task Force—a panel of medical experts—issued new guidelines for patients, recommending only those at risk for heart attacks or strokes should take a daily aspirin. Risk factors include having high blood pressure, high cholesterol and diabetes, as well as being overweight.

The panel also recommended that people over 80 not take aspirin at all because of bleeding risk.

For the first time, the panel also broke down its advice by gender, recommending against daily aspirin use in women under 55 and men under 45.

Is it right for you?

So, should you take a daily aspirin or not? The answer is not quite as simple as doctors previously thought. Aspirin, they say, can still be a lifesaving drug, but it’s not for everyone.
For reasons researchers don’t fully understand, aspirin seems to provide different benefits for men and women.

In men, aspirin can prevent heart attacks but seems to have no effect on strokes, says Michael LeFevre, M.D., a member of the task force that wrote the new guidelines and a professor of family medicine at the University of Missouri. Conversely, he says, aspirin appears to help women avoid strokes but not heart attacks.

The new recommendations suggest that aspirin will be most beneficial to:
men between 45 and 79 who have a high risk for heart attacks;
women between 55 and 79 who are at high risk for strokes.

Drawbacks

Aspirin, which has been around for more than 100 years, is a cheap, easy, effective way to control pain and inflammation. In 1989, when a major study revealed that a small dose could reduce the risk of stroke and heart attack by preventing blood clots, doctors began recommending that their older patients take a low dose of aspirin, 81 mg, every day.

“Aspirin is a lifesaving medicine in patients with established cardiovascular disease,” says Jeffrey Berger, M.D., a cardiologist at New York University who has studied the use of aspirin. But, he warns, it does come with some real drawbacks.
Aspirin has been linked with chronic ringing in the ears (tinnitus), and earlier this year scientists reported that people who took aspirin regularly were more likely to suffer from hearing loss.

Dangerous bleeding

The drug’s ability to prevent blood clots is also a double-edged sword. The body’s ability to stop bleeding is what prevents a small cut, for instance, from causing uncontrollable bleeding. While aspirin might keep clots from blocking blood flow to our hearts and brains, it also makes it more likely that we might develop serious internal bleeds, particularly in the stomach. “That’s not a trivial side effect,” says LeFevre. “We’re talking about people who get hospitalized” and may end up in the intensive care unit, he adds.

Some patients are more likely to suffer these complications than others; a recent review of the research reveals that men are twice as likely to experience bleeds as women, and the risk also increases with age. Researchers estimate the risk of internal bleeding for those who take aspirin is two to four times greater than for those who don’t take aspirin at all, depending on factors such as age and overall health.

Even though people are more likely to bleed as they get older, researchers don’t think aspirin causes the risk of bleeding to build up over time. “In fact, it’s likely that if one is to bleed, their risk of bleeding is seen early on,” Berger says.

Taking ibuprofen and naproxen—common pain relievers such as Advil and Aleve—also can make bleeding more likely. Unfortunately, this kind of severe bleeding doesn’t usually come with obvious warning signs, but sudden gastrointestinal pain can be a tip-off. The bleeding is often caused by inflammation of the stomach lining or an aspirin-induced ulcer and can result in vomiting blood or blood in the stool.

The traditional point of view, LeFevre says, was: “Aspirin is a pretty benign thing. Why doesn’t everybody take one? Aspirin, as it turns out, is not harmless.”

Strokes vs. heart attacks

Many of the risk factors for heart attacks and strokes—including age, diabetes and smoking—overlap, but there are slight differences. High total cholesterol and high levels of LDL or “bad” cholesterol, for instance, are important predictors of heart attacks.

The most important risk factors for strokes include high blood pressure, certain kinds of irregular heartbeats (known as atrial fibrillation) and a condition known as left ventricular hypertrophy in which some of the heart muscle thickens.

Experts agree that women who have already had strokes and men who have already had heart attacks should absolutely be taking aspirin. “You have to make sure that people with a history of heart attack or stroke do not stop their aspirin, because it could be a deadly mistake,” says NYU’s Berger.

Clearly, the benefits of aspirin have to be weighed against the possibility of bleeding, and that’s a conversation that experts say every patient needs to have with his or her doctor.
“This decision has to be made one person at a time,” LeFevre says. “There is no one blanket recommendation for everybody.”

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