What are the recommendations for aspirin (acetylsalicylic acid) dosage and usage in patients at high risk of cardiovascular events?

Aspirin Recommendations for Patients at High Risk of Cardiovascular Events

Low-dose aspirin (75-162 mg/day) is strongly recommended for all patients with established cardiovascular disease for secondary prevention, while for primary prevention in high-risk individuals, aspirin should be considered only for adults aged 50-70 years with ≥10% 10-year cardiovascular risk and low bleeding risk. 1

Secondary Prevention (Established Cardiovascular Disease)

• For patients with a history of atherosclerotic cardiovascular disease, aspirin therapy (75-162 mg/day) is strongly recommended as a secondary prevention strategy 2, 1
• For patients with documented aspirin allergy, clopidogrel (75 mg/day) should be used as an alternative 2
• Dual antiplatelet therapy (low-dose aspirin plus a P2Y12 inhibitor) is reasonable for one year after an acute coronary syndrome and may have benefits beyond this period 2
• In secondary prevention, aspirin prevents approximately 25% of serious vascular events 3

Primary Prevention (High-Risk Individuals Without Established CVD)

Patient Selection Algorithm:

1. Age and Risk Assessment:

   • Consider aspirin for adults aged 50-70 years with high cardiovascular risk (≥10% 10-year risk)
   • Generally not recommended for adults >70 years due to increased bleeding risk 2, 1
   • Not recommended for those <50 years unless exceptional risk factors present

2. Risk Stratification:

   CV Risk	Bleeding Risk	Recommendation
   High (≥10%)	Low	Consider aspirin 75-162 mg/day
   Moderate (6-10%)	Low	Individualized decision based on risk factors
   Low (<6%)	Any	Aspirin generally not recommended
   Any	High	Aspirin generally not recommended

3. For Diabetic Patients:

   • Consider aspirin (75-162 mg/day) for primary prevention in adults with diabetes who are ≥50 years with at least one additional major risk factor (family history of premature ASCVD, hypertension, dyslipidemia, smoking, or chronic kidney disease/albuminuria) 2
   • Not recommended for diabetic patients <50 years with no other major ASCVD risk factors 2

Dosing Recommendations

• Secondary Prevention: 75-162 mg/day 2, 1
• Primary Prevention: 75-162 mg/day when indicated 1
• Acute Coronary Syndrome: Initial loading dose of 160-325 mg, followed by 75-162 mg/day maintenance 2, 1

Important Considerations:

• Lower doses (75-100 mg) are preferred for long-term use to minimize bleeding risk while maintaining efficacy 2, 1
• Higher doses have not been associated with proportionally greater cardiovascular benefit 4, 5
• Daily doses of 75-81 mg may optimize efficacy and safety, especially for patients on dual antiplatelet therapy 5

Contraindications and Cautions

• Absolute contraindications: Active peptic ulcer disease, history of aspirin allergy, severe liver disease, bleeding disorders 1
• Relative contraindications: History of GI bleeding/ulcers, age >70 years, concurrent anticoagulant or NSAID use, uncontrolled hypertension 1
• Pediatric patients: Contraindicated in patients <21 years due to risk of Reye syndrome 2, 1

Bleeding Risk Assessment

• Major bleeding risk increases with aspirin use (GI bleeding OR 1.59-1.72; intracranial hemorrhage OR 1.27 in women and 1.69 in men) 1
• In primary prevention trials, gastrointestinal bleeding events occurred in 0.97% of patients in the aspirin group vs. 0.46% in the placebo group (HR 2.11) 6
• For high-risk patients, the absolute benefits of aspirin therapy substantially outweigh the absolute risks of major bleeding complications 2

Key Pitfalls to Avoid

1. Inappropriate discontinuation: Abrupt discontinuation in patients with established CVD increases risk of cardiovascular events 1

2. Drug interactions: Concurrent use with NSAIDs or anticoagulants significantly increases bleeding risk; ibuprofen may block aspirin's cardioprotective effects when taken together 1

3. Overuse in low-risk patients: For primary prevention in low-risk individuals, the benefit/risk profile is unfavorable 2, 6

4. Underuse in high-risk patients: Despite clear benefits, aspirin remains underutilized in appropriate secondary prevention cases 3

5. Inappropriate dosing: Using unnecessarily high doses increases bleeding risk without additional cardiovascular benefit 4, 5

Remember that aspirin should be an adjunct to, not a replacement for, management of other cardiovascular risk factors including lifestyle modifications, blood pressure control, lipid management, and smoking cessation.