Aspirin for Primary Prevention of CVD and Colorectal Cancer

Bibbins-Domingo K, on behalf of the U.S. Preventive Services Task Force.
Aspirin Use for the Primary Prevention of Cardiovascular Disease and Colorectal Cancer: U.S. Preventive Services Task Force Recommendation Statement. Ann Intern Med 2016;Apr 12:[Epub ahead of print].

The following are key points to remember about this recommendation statement on aspirin use for the primary prevention of cardiovascular disease (CVD) and colorectal cancer:

  1. The U.S. Preventive Services Task Force (USPSTF) makes recommendations about the effectiveness of specific preventive care services (diagnostic or treatment) for patients without obvious related signs or symptoms. Recommendations are based on the balance of the evidence of both the benefits and harms, and do not consider the costs. USPSTF recognizes that clinical decisions involve more considerations than evidence alone, and clinicians should understand the evidence, but individualize decision making to the specific patient or situation.
  2. The USPSTF used a calculator derived from the American College of Cardiology/American Heart Association pooled cohort equations to predict 10-year risk for first atherosclerotic CVD event. Primary risk factors for CVD are older age, male sex, race/ethnicity, abnormal lipid levels, high blood pressure, diabetes, and smoking.
  3. Risk factors for gastrointestinal (GI) bleeding with aspirin use include higher aspirin dose and longer duration of use, nonsteroidal anti-inflammatory drugs, history of GI ulcers or upper GI pain, bleeding disorders, renal failure, severe liver disease, and thrombocytopenia.
  4. The USPSTF recommends initiating low-dose aspirin for the primary prevention of CVD including myocardial infarction (MI) and ischemic stroke, and colorectal cancer (CRC) in adults aged 50-59 years who have a ≥10% 10-year CVD risk, are not at increased risk for bleeding, have a life expectancy of ≥10 years, and are willing to take low-dose aspirin daily for ≥10 years (Grade B). The evidence that a long duration of use of aspirin is necessary is from studies of CRC.
  5. The mechanism for reducing CV events is considered to be prevention of vascular thrombi at sites of plaque, and for inhibition of adenomas or colorectal cancer is not clear, but may be anti-inflammatory.
  6. The decision to initiate low-dose aspirin use for the primary prevention of CVD and CRC in adults ages 60-69 years who have a ≥10% 10-year CVD risk should be an individual one. Persons who are not at increased risk for bleeding have a life expectancy of ≥10 years, and are willing to take low-dose aspirin daily for ≥10 years are more likely to benefit, with benefit outweighing harm (Grade C).
  7. For adults <50 years, and those ≥70 years, there is not enough evidence for a recommendation.
  8. For 10,000 men taking aspirin who are ages 50-59 years and have a 10% risk of CVD, 225 nonfatal MIs, 84 ischemic strokes, and 139 colorectal cancers would be prevented with 284 serious GI bleeds and 23 hemorrhagic strokes caused. In women of the same age, significantly less nonfatal MIs would be prevented, but with a greater reduction in ischemic strokes, comparable CRC prevented, and with a similar number of serious GI bleeds and hemorrhagic strokes created.

Perspective: The important recommendation by this conservative group is the prevention of adenomas and colorectal cancer in men and women who take low-dose aspirin for a relatively long period (at least 5-10 years). To what degree the benefit/harm ratio of aspirin would lessen in patients on statins and otherwise optimal treatment is not known and needs to be considered.

Clinical Topics: Dyslipidemia, Prevention, Lipid Metabolism, Hypertension, Smoking

Keywords: Adenoma, Anti-Inflammatory Agents, Non-Steroidal, Aspirin, Cardiovascular Diseases, Colorectal Neoplasms, Diabetes Mellitus, Hemorrhage, Hypertension, Life Expectancy, Lipids, Myocardial Infarction, Primary Prevention, Renal Insufficiency, Risk Factors, Smoking, Stroke, Thrombocytopenia

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