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Figure 2. Estimated myocardial infarctions (MIs) prevented and estimated harms of using aspirin for 10 years in a hypothetical cohort of 1000 men

As indicated, the estimated number of MIs prevented varies with 10-year CHD risk. The estimated harms of using aspirin vary with age. Therefore, both 10-year CHD risk and age must be considered when determining whether the potential harms of aspirin use outweigh the potential benefit in terms of MIs prevented. The boldfaced numbers indicate the combinations of 10-year CHD risk and age for which the number of harms (GI bleeding and hemorrhagic stroke) are greater than or approximately equal to the number of MIs prevented.*

Variable Estimated MIs Prevented (per 1000 Men), n
Age 45-59 Years Age 60-69 Years Age 70-79 Years
10-year CHD risk  
1% 3.2 3.2 3.2
2% 6.4 6.4 6.4
3% 9.6 9.6 9.6
4% 12.8 12.8 12.8
5% 16 16 16
6% 19.2 19.2 19.2
7% 22.4 22.4 22.4
8% 25.6 25.6 25.6
9% 28.8 28.8 28.8
10% 32 32 32
11% 35.2 35.2 35.2
12% 38.4 38.4 38.4
13% 41.6 41.6 41.6
14% 44.8 44.8 44.8
15% 48 48 48
16% 51.2 51.2 51.2
17% 54.4 54.4 54.4
18% 57.6 57.6 57.6
19% 60.8 60.8 60.8
20% 64 64 64
  Estimated Harms, n
Type of event  
GI bleeding 8 24 36
Hemorrhagic stroke 1 1 1

* Calculations of estimated benefits and harms rely on assumptions and are by nature somewhat imprecise. Estimates of benefits and harms, especially at the borders of the boldfaced and non-boldfaced areas, should be considered in the full context of clinical decision making and used to stimulate shared decision making. The calculations in the table are based on the following assumptions: that there is a 32% risk reduction of MIs with regular aspirin use3 and that gastrointestinal bleeding includes serious hemorrhage, perforation, or other complications leading to hospitalization or death. The harm of GI bleeding in the table assumes that the risk for GI bleeding increases with age and that the men are not taking nonsteroidal antiinflammatory drugs, do not have upper GI pain, or do not have a history of GI ulcer.2

Estimates are based on age and 10-year CHD risk. CHD = coronary heart disease; GI = gastrointestinal; MI = myocardial infarction.

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