Putting Prevention into Practice: An Evidence-Based Approach

Aspirin for the Primary Prevention of Cardiovascular Events



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Am Fam Physician. 2002 Nov 1;66(9):1737-1738.

Case Study

ST is a 55-year-old man who you see regularly for hypertension and depression. He is overweight and sedentary, and his elder sister recently had a heart attack. He asks you whether he should take a daily aspirin, “just in case.”

Case Study Question

1. Which one of the following statements best reflects the new U.S. Preventive Services Task Force (USPSTF) recommendations regarding aspirin for the primary prevention of cardiovascular events?

  • A. A daily aspirin is recommended only for men over age 40.

  • B. Aspirin is recommended for both men and women ages 50 to 75.

  • C. Physicians should discuss benefits and harms of aspirin chemoprevention with adults who are at increased risk of heart disease.

  • D. Aspirin is recommended for all men and women with at least one cardiovascular risk factor.

2. Which of the following factors should be considered in the decision about whether to recommend aspirin to ST?

  • A. His age and gender.

  • B. Whether he has diabetes or hyperlipidemia.

  • C. His level of tobacco use.

  • D. Whether he is at increased risk for gastrointestinal bleeding.

  • E. His family history of coronary heart disease.

Answers

1. The correct answer is C. The USPSTF strongly recommends that clinicians discuss the potential benefits and harms of chemo-prevention with adults at increased risk of coronary heart disease (CHD), but it does not make specific recommendations about who should receive aspirin chemoprevention. The USPSTF found good evidence that aspirin decreases the incidence of CHD in adults at increased risk. A meta-analysis of five trials of aspirin chemoprevention showed that aspirin therapy reduced the risk of CHD by 28 percent, with particular benefit in reducing myocardial infarction. The most common harm is an increased risk of gastrointestinal bleeding. Aspirin appears to modestly increase risk of hemorrhagic strokes, but the overall risk of stroke is not increased. The USPSTF concluded that benefits exceed harms in patients whose five-year risk of CHD is at least 3 to 5 percent. The benefits of aspirin for secondary prevention in individuals who have already had a stroke, transient ischemic attack, or myocardial infarction are well established.

2. The correct answers are A, B, C, D, and E. The decision to institute aspirin therapy should take into account the balance of overall risk of CHD and risk of complications from aspirin use. Risk assessment should include the presence and severity of the following CHD risk factors: age, gender, diabetes, elevated total cholesterol levels, low levels of high-density lipoprotein (HDL) cholesterol, elevated blood pressure, family history, and smoking. Risk calculators that incorporate specific information on multiple risk factors provide a more accurate estimation of cardiovascular risk than simply counting the number of risk factors (www.intmed.mcw.edu/clincalc/heartrisk.html). The risk-benefit ratio for aspirin chemoprevention becomes more favorable as CHD risk increases. In addition, the increased risk of bleeding and hemorrhagic stroke from aspirin should be considered. Benefits exceed harms in individuals who have a baseline risk of cardiovascular disease of at least 3 to 5 percent over five years. Although aspirin chemoprevention decreases the risk of cardiac events, there is no clear reduction in total mortality or stroke. Rates of major gastrointestinal bleeding are approximately 2 to 4 per 1,000 for middle-aged individuals and 4 to 12 per 1,000 for older individuals who receive aspirin for five years. Uncontrolled hypertension and concomitant use of nonsteroidal anti-inflammatory drugs increase the risk for serious bleeding. Enteric-coated or buffered preparations do not clearly reduce adverse gastrointestinal effects of aspirin. The optimum dosage of aspirin for chemoprevention is not known. Dosages of about 75 mg daily (baby aspirin is 81 mg) appear as effective as higher dosages; whether dosages below 75 mg daily are effective is not established.

The case study and answers to the following questions on aspirin for the prevention of cardiovascular disease are based on the recommendations of the current U.S. Preventive Services Task Force (USPSTF), part of the Put Prevention into Practice program of the Agency for Healthcare Research and Quality (AHRQ). This recommendation was released in 2002 and is an update of the 1996 recommendation on aspirin for the prevention of cardiovascular events. More detailed information on this subject is available in the Systematic Evidence Review, Summary of the Evidence, and USPSTF Recommendations and Rationale on the AHRQ Web site (www.ahrq.gov) and in print through the AHRQ Publications Clearinghouse (800-358-9295).

This case study is part of AFP's CME. See “Clinical Quiz” on page 1603.



Copyright © 2002 by the American Academy of Family Physicians.
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