Eighty billion aspirin tablets are taken every year to cure pain, inflammation and fevers and even for its cardioprotective effects.
But is aspirin right for you? The answer, say doctors, lies in measuring your health with a risk-benefit ratio.
Aspirin’s values and potential hazards come from the same source: Its ability to prevent the cells in the blood from clotting. The benefit to taking aspirin therapy is to prevent heart attack and ischemic (a blood clot) stroke, but it is not recommended to everybody because it increases the risk for serious bleeding in the gastrointestinal tract and brain (hemorrhagic stroke).
Interventional cardiologist Nabi Dib, M.D., from Arizona Heart Institute in Phoenix, explains the net benefit of aspirin increases with increasing risk for a heart attack or stroke including age, gender, high cholesterol, diabetes, strong family history, hypertension, and smoking.
The highest risk factor for a heart attack or ischemic stroke is having already had one. In general, if you belong to this group the Food and Drug Administration and the American Heart Association, among others, say the benefits of a daily aspirin will far outweigh the risks. Also in this group, known as secondary prevention, are patients with known coronary artery disease, atherosclerosis, cerebral vascular disease, or peripheral vascular disease.
On the other hand, if you are a healthy 30-year-old with no major risk factors, the risks will far outweigh the benefits.
But then there is a large group of people who fall into the middle category whose prescription is not so clear. Some doctors like Dr. Dib draw the line for aspirin therapy at people who have two or more risk factors for coronary artery disease.
It is also important to note the risk factors are not dichotomous, says cardiologist John Alexander, M.D., from Duke University Medical Center in Durham, N.C. For example, a patient may have only one risk factor, but if it is very severe high cholesterol or family history, it may call for aspirin therapy.
The largest study on aspirin therapy was performed with 325 milligrams of aspirin, or one adult aspirin tablet. In deciding which dose to take, cardiologist Paul Hirsh, M.D., from St. Luke’s Hospitals in Cincinnati, says, “If you want to go purely on the largest data then you probably ought to take the 325-milligram tablet.”
However, these doctors agree that taking a baby aspirin tablet, 81 milligrams, seems to be sufficient, which has been proven in smaller studies. Interestingly, Dr. Alexander says, the 325-milligram dose was used when aspirin was first invented over 100 years ago because that was the size that was easiest to combine with starch to form the pill.
Dr. Hirsh says some of his patients on aspirin therapy complain they are bruising too easily and wonder if that is a sign they should be taking a smaller dose. “The problem with that approach is that is the dose that is effective. We’re thinning the blood so you don’t get a spontaneous blood clot forming in a coronary artery. So, if you cut the dose so your blood isn’t so thin then you may be at risk for having that blood clot.” Dr. Alexander adds that aspirin itself won’t cause bruises unless there is also a defect in the wall of the blood vessel. Aspirin doesn’t cause bleeding, it just prevents it from stopping as easily.
The only time when a 325-milligram dose is always recommended immediately is when a patient is having a heart attack. Dr. Alexander explains this dose is to err on the side of precaution, and any risk of a one-time dose of 325 milligrams of aspirin is negligible.
The medical profession agrees aspirin is safe to take with most other drugs. Recent research, contrary to what was previously believed, has shown that aspirin does not affect how the blood pressure medication ACE inhibitors work.
However, it has been suggested that aspirin may interact negatively with some supplements such as vitamin E and omega-3 fatty acids in fish oils. Aspirin has yet to have large studies completed on its interaction with these. In the meantime, Dr. Hirsh recommends you do one or the other as therapy, and the one that is proven is aspirin.
In general, it is recommended to avoid taking non-steroidal anti-inflammatory drugs like Motrin or Advil with a daily aspirin. NSAIDs have the same effect on platelets and you may be more prone to the consequence of bleeding. However, people with arthritis, among others, often find themselves needing to take both NSAIDs and aspirin, and Dr. Hirsh says many of them do it without difficulty. This is an example of where your doctor can advise you best.
In their advisory pamphlet, the Food and Drug Administration says the chance of side effects increases with each new product you use, including over-the-counter medications, prescriptions, and vitamins and herbals. Additionally, the FDA warns against aspirin use with alcohol and other products that contain aspirin like cough, cold or sinus drugs.
Doctors say you cannot take aspirin for too long, but look out for stomach upset, black stool, anemia, and high blood pressure to recognize any bleeding caused by aspirin.
Doctors and researchers are now trying to define aspirin resistance. “On biochemical tests it looks like there is variability, not surprisingly, not all people are alike, in the way people respond to aspirin. That is probably true with all drugs. We know a lot, and yet, we have so much to learn about the best way to tailor aspirin therapy,” Dr. Alexander says.
The whole issue of aspirin resistance came about by studying blood work and observing different reactions of people on aspirin therapy. There is no consensus on exactly what aspirin resistance looks like, how best to test for it, or how to treat it.
“For the present, aspirin resistance shouldn’t change the way we do things. We have approaches that are tried and true with the doses of aspirin we’re using across large populations, and that’s what we should all stick to until the issue of aspirin resistance has been further worked out,” Dr. Hirsh advises. Experts agree this may be a larger component of aspirin therapy in the future.
The Future of Aspirin Therapy:
In 2003, researchers publishing in the Archives of Internal Medicine analyzed five studies conducted on aspirin primary and secondary prevention. Among the 55,580 in the five trials, aspirin was associated with a statistically significant 32-percent reduction in the risk of a first heart attack and a significant 15-percent reduction in the risk of all important vascular events. In terms of the risk for hemorrhagic stroke, the five trials suggest an increased risk of one to two per 1,000 patients, which is the same risk found in secondary prevention.
Even with this proof of its success, the study authors say there is underutilization and mismedication with acetaminophen or NSAIDs instead of aspirin. They conclude the more widespread and appropriate use of aspirin would prevent more than 150,000 cardiovascular events in primary prevention.
But before you run out and get an economy-sized bottle of aspirin, the U.S. Preventive Services Task Force recommends you discuss with your doctor the potential benefits and drawbacks of taking aspirin before you start to take it.
And in the future, you might even be prescribed aspirin to prevent some cancers, Alzheimer’s disease and preeclampsia.
This article was reported by Ivanhoe.com, who offers Medical Alerts by e-mail every day of the week. To subscribe, go to: http://www.ivanhoe.com/newsalert/.