Does Aspirin Prevent Heart Disease and Cancer?

A new statistical review of many studies has found that aspirin, taken daily or every other day in low doses for primary prevention of cardiovascular death in patients without existing cardiovascular disease, was not effective in these patients in reducing cardiovascular death or death from cancer.

Aspirin did, however, increase clinically important bleeding events.

This statistical review, called a meta-analysis, combined the results of nine gold-standard randomized clinical trials involving 103,000 patients without previous cardiovascular disease. Archives of Internal Medicine published the meta-analysis in its Jan. 9, 2012, issue.

The patients in the analysis were followed for an average of six years. Most took between 81 milligrams (mg) and 100 mg of aspirin daily or every other day.

Meta-analysis overview

The authors of the meta-analysis aimed to assess whether the benefits of aspirin for those without known cardiovascular disease would outweigh aspirin’s increased risk of serious bleeding.

The researchers used an outcome they termed “nontrivial bleeding” to evaluate the risks of treatment with low doses of aspirin daily or every other day. This outcome included fatal bleeding from any site, bleeding in the brain or eye, bleeding in the intestines and bleeding requiring hospitalization and/or transfusion.

The researchers assessed the benefits of aspirin for primary prevention based on another outcome called Total Coronary Heart Disease, which included both fatal and non-fatal heart attacks.

To gauge aspirin’s benefits, the researchers calculated the number of people who had to be treated with aspirin to prevent one outcome, such as a nonfatal heart attack or one cancer death. This is called the Number Needed to Treat (NNT). This number, in essence, measures how many people would have to be treated to achieve the benefit in just one of all of those treated.

The authors similarly computed the risk of harm from aspirin by calculating the number of patients treated before one patient would experience nontrivial bleeding. This is called the Number Needed to Harm (NNH).

Conclusions
The NNT to prevent one nonfatal heart attack over the six years of the study was 162. The NNT to prevent one cancer death over six years was 247. However, aspirin caused at least one nontrivial bleeding event for every 73 persons treated over the same six years of treatment.

The authors concluded:

Despite important reductions in nonfatal MI [heart attacks], aspirin prophylaxis in people without prior CVD [cardiovascular disease] does not lead to reductions in either cardiovascular death or cancer mortality.

What You Can Do

If you are thinking about taking aspirin to prevent cardiovascular disease or cancer, be aware of two important considerations:

First, aspirin is not a simple over-the-counter drug that may help but won’t hurt. The important drug demonstrates documented benefits in some groups of patients, but it can sometimes cause serious life-threatening bleeding.

Second, the use of aspirin for the secondary prevention of cardiovascular disease is effective and should be recommended. If you have cardiovascular disease (e.g., you have had a heart attack), you should be under the care of a physician.

A consultation with your doctor is equally important if you do not have previous cardiovascular disease. We agree with the meta-analysis authors’ conclusion:

Because the benefits [to those without previous cardiovascular disease] are further offset by clinically important bleeding events, routine use of aspirin for primary prevention is not warranted and treatment decisions need to be considered on a case-by-case basis.

Consumers may report serious adverse events with drugs or product quality problems to the Food and Drug Administration’s (FDA’s) MedWatch Adverse Event Reporting program online or by regular mail, fax or phone. This also applies to aspirin.

• Online: www.accessdata.fda.gov/scripts/medwatch/medwatch-online.htm
• Regular mail: Use postage-paid, pre-addressed FDA form 3500 and mail to MedWatch, 5600 Fishers Lane, Rockville, MD 20852-9787
• Fax: (800) FDA-0178
• Phone: (800) FDA-1088