Should I prescribe aspirin (ASA) or clopidogrel for a 90-year-old patient?

Antiplatelet Therapy in a 90-Year-Old Patient: ASA vs Clopidogrel

For a 90-year-old patient, clopidogrel 75 mg daily is generally preferred over aspirin (ASA) due to lower bleeding risk, particularly gastrointestinal bleeding, while maintaining effective antiplatelet protection.

Decision Algorithm for Antiplatelet Selection in Elderly Patients

Primary Considerations for 90-Year-Old Patients

1. Bleeding Risk Assessment:

   • Advanced age (90 years) significantly increases bleeding risk with any antiplatelet therapy
   • Gastrointestinal bleeding risk is 45% higher with aspirin compared to clopidogrel 1
   • Absolute annual increase in major GI bleeding with aspirin vs clopidogrel is 0.12% 1

2. Clinical Indication Evaluation:

   • For secondary prevention (post-stroke, TIA, or established cardiovascular disease):

     • Clopidogrel 75 mg daily is recommended for patients who cannot tolerate aspirin 2
     • Clopidogrel may be slightly more effective than aspirin for vascular event prevention 2

   • For primary prevention:

     • Neither agent is strongly recommended in patients >70 years due to bleeding risk outweighing benefits 2

Specific Clinical Scenarios

For Established Coronary Artery Disease:

• If >12 months post-PCI: Oral anticoagulant alone (if indicated) or single antiplatelet therapy 2
• If stable ischemic heart disease (SIHD) without recent events: Clopidogrel 75 mg daily is preferred over aspirin in elderly patients with high bleeding risk 2

For Recent Acute Coronary Syndrome:

• If <12 months post-ACS: Consider clopidogrel 75 mg daily rather than aspirin in elderly patients with high bleeding risk 2
• For patients >75 years with ACS: Avoid prasugrel due to increased bleeding risk 2

Evidence-Based Rationale

The preference for clopidogrel in very elderly patients is supported by several key findings:

1. Bleeding Risk Profile:

   • Systematic reviews demonstrate that while aspirin increases major bleeding risk by approximately 70% versus placebo, clopidogrel has a more favorable GI bleeding profile than aspirin 1
   • In elderly patients, the absolute risk reduction for cardiovascular events must be carefully balanced against bleeding risk

2. Efficacy Considerations:

   • For secondary prevention, clopidogrel has demonstrated comparable or slightly superior efficacy to aspirin 2
   • The 2011 ACC/AHA guidelines specifically recommend clopidogrel when aspirin is contraindicated or not tolerated 2

3. Dosing Considerations:

   • If aspirin is chosen despite higher bleeding risk, low-dose aspirin (75-100 mg) is preferred over higher doses 2
   • For clopidogrel, the standard dose of 75 mg daily is appropriate for elderly patients 3

Important Caveats and Pitfalls

• Avoid dual antiplatelet therapy unless specifically indicated (recent ACS, recent stent), as bleeding risk is substantially higher in elderly patients
• Consider drug interactions - particularly proton pump inhibitors which may reduce clopidogrel efficacy 4
• Renal function assessment is important as severe renal impairment may reduce clopidogrel's antiplatelet effect 3
• Discontinuation timing - if surgery is anticipated, clopidogrel should be discontinued 5-7 days prior when possible 3
• Cost considerations - clopidogrel is more expensive than aspirin, but generic formulations have improved affordability

Special Considerations for the 90-Year-Old Patient

• Frailty assessment is crucial - very frail patients may have higher bleeding risk with any antiplatelet therapy
• Fall risk should be evaluated as traumatic bleeding risk increases with antiplatelet use
• Polypharmacy - evaluate all medications for potential interactions with antiplatelet therapy
• Cognitive status - ensure medication adherence capability or appropriate support

In summary, while the decision must consider the specific indication for antiplatelet therapy, clopidogrel 75 mg daily generally offers the best balance of efficacy and safety for a 90-year-old patient requiring antiplatelet therapy.