Should an elderly female with thrombocytosis (elevated platelet count) start aspirin therapy?

Should an Elderly Female Start Aspirin for Platelets of 495?

No, aspirin should not be routinely started in an elderly female with thrombocytosis (platelet count 495×10⁹/L) until the underlying cause is determined and individual thrombotic/bleeding risks are carefully assessed.

Critical First Step: Determine the Cause of Thrombocytosis

The decision to use aspirin depends entirely on whether this represents reactive thrombocytosis versus a myeloproliferative neoplasm (MPN) such as essential thrombocythemia (ET) or polycythemia vera (PV). 1

• Reactive thrombocytosis (even at counts >1,000×10⁹/L) has never been shown to cause thrombosis and does not require aspirin therapy 2
• Essential thrombocythemia or polycythemia vera may benefit from aspirin, but only in specific risk-stratified scenarios 1

Required workup includes: JAK2 V617F mutation testing, CALR mutation testing, bone marrow biopsy if indicated, and evaluation for reactive causes (infection, inflammation, iron deficiency, malignancy, recent surgery). 1

If This is Reactive Thrombocytosis

Do not start aspirin. Treat the underlying condition causing the elevated platelet count. 2

If This is Essential Thrombocythemia (ET)

The decision depends on risk stratification:

Very Low-Risk ET

• Observation alone is appropriate without aspirin 1
• This applies to patients with no prior thrombosis, no cardiovascular risk factors, and no JAK2 mutation

Low-Risk ET (No Prior Thrombosis, Age <60)

Withhold aspirin if platelet count >1,000×10⁹/L due to acquired von Willebrand disease risk causing paradoxical bleeding 1, 3, 4

Consider aspirin 81-100 mg daily only if:

• JAK2 mutation is present, OR
• Cardiovascular risk factors exist (hypertension, diabetes, smoking, dyslipidemia) 1

Intermediate or High-Risk ET (Prior Thrombosis or Age ≥60)

Aspirin 81-100 mg daily is recommended for intermediate-risk patients 1

Cytoreductive therapy PLUS aspirin 81-100 mg daily is standard for high-risk patients 1, 5

If This is Polycythemia Vera (PV)

All PV patients require aspirin 81-100 mg daily plus phlebotomy to maintain hematocrit <45%, regardless of age or risk category, based on the ECLAP study showing significant reduction in cardiovascular events. 1, 6

Special Considerations for Elderly Patients

Age-Related Bleeding Risk

For patients >70 years of age, aspirin for primary prevention generally has greater risk than benefit and is not recommended in the absence of established cardiovascular disease. 6

This creates a clinical dilemma:

• If this elderly patient has reactive thrombocytosis: No aspirin needed 2
• If she has ET without high-risk features: The bleeding risk from aspirin likely outweighs benefit given her age 6
• If she has ET with prior thrombosis or PV: Aspirin is indicated despite age, as secondary prevention benefits outweigh risks 6, 1

Bleeding Risk Assessment Required

Before starting aspirin in any elderly patient, assess for:

• History of gastrointestinal bleeding or peptic ulcer disease
• Anemia (which increases bleeding risk) 6
• Renal insufficiency (increases bleeding risk) 6
• Concurrent anticoagulation or antiplatelet therapy
• Falls risk

Aspirin Dosing if Indicated

Use plain aspirin 81-100 mg daily (not enteric-coated, which shows poor platelet inhibition in some ET patients) 1, 6

• Higher doses (>100 mg) provide no additional benefit but significantly increase gastrointestinal bleeding risk 6, 1
• Twice-daily dosing may be considered only for persistent vasomotor symptoms (erythromelalgia, transient ischemic attacks) in carefully selected patients 1, 7

Monitoring if Aspirin is Started

• Screen for acquired von Willebrand disease before initiating aspirin if platelet count approaches or exceeds 1,000×10⁹/L 1, 3
• Monitor for bleeding symptoms, particularly in the first 3 months 1
• Assess platelet count every 3-6 months 1
• Consider cytoreductive therapy if platelets rise >1,000×10⁹/L 1, 5

Common Pitfalls to Avoid

Do not reflexively start aspirin for any elevated platelet count without determining the underlying cause—reactive thrombocytosis does not benefit from aspirin and only increases bleeding risk. 2

Do not use aspirin in elderly patients with platelet counts >1,000×10⁹/L without first excluding acquired von Willebrand syndrome, as this creates severe bleeding risk. 1, 3, 4

Do not assume aspirin provides adequate thromboprophylaxis in high-risk MPN—cytoreductive therapy is required to normalize platelet counts. 1, 5