Should aspirin be started in a patient with polycythemia?

Aspirin Therapy for Polycythemia Vera

Low-dose aspirin (100mg daily) should be started in this 64-year-old female patient with laboratory values consistent with polycythemia vera (RBC 6.07, Hgb 17.3, Hct 53.3). 1, 2

Diagnosis and Risk Assessment

• The patient's elevated hematocrit (53.3%), hemoglobin (17.3 g/dL), and red blood cell count (6.07) are consistent with polycythemia vera (PV), which carries an increased risk of both arterial and venous thrombotic complications 1
• At 64 years old, this patient is considered high-risk for thrombotic complications according to established risk stratification criteria (age >60 years) 1, 2
• The current hematocrit of 53.3% is significantly above the recommended target of <45%, further increasing thrombotic risk 1, 2

Treatment Recommendations

Phlebotomy

• Immediate phlebotomy should be initiated to reduce the hematocrit to below 45% 1
• The CYTO-PV trial demonstrated that maintaining hematocrit <45% significantly reduced the risk of cardiovascular death and major thrombotic events compared to a target of 45-50% 1, 2
• For women specifically, a target hematocrit of 42% may be more appropriate given normal sex differences in hematocrit values 1, 2

Aspirin Therapy

• Low-dose aspirin (100mg daily) is strongly recommended as it has been shown to significantly reduce thrombotic complications in PV 1, 2
• The ECLAP study (European Collaboration on Low-dose Aspirin in Polycythemia Vera) demonstrated that aspirin reduced the risk of the combined endpoint of nonfatal myocardial infarction, nonfatal stroke, pulmonary embolism, major venous thrombosis, or death from cardiovascular causes (relative risk, 0.40; 95% CI, 0.18 to 0.91; P=0.03) 3, 4
• The benefit of aspirin therapy outweighs the bleeding risk in PV patients without specific contraindications to aspirin 3, 5

Cytoreductive Therapy

• Given the patient's age >60 years, cytoreductive therapy with hydroxyurea should also be considered in addition to aspirin and phlebotomy 1
• Hydroxyurea is the preferred cytoreductive agent for patients over 40 years of age 2, 1
• Starting dose is typically 500mg twice daily, adjusted to maintain target blood counts 2

Monitoring and Follow-up

• Regular monitoring of complete blood counts to ensure hematocrit remains <45% 1, 2
• Assessment for signs and symptoms of thrombosis or bleeding 1, 2
• Evaluation for acquired von Willebrand disease, which can increase bleeding risk in patients with very high platelet counts 1
• Management of cardiovascular risk factors (smoking cessation, blood pressure control) is essential as these further increase thrombotic risk in PV 1, 4

Special Considerations

• For patients with inadequate response to once-daily aspirin (persistent symptoms or evidence of incomplete platelet inhibition), twice-daily aspirin (100mg twice daily) may be considered 1, 6
• In patients with very high platelet counts, aspirin should be used with caution due to potential acquired von Willebrand disease 1
• Enteric-coated aspirin has lower bioavailability and may result in inadequate platelet inhibition; regular aspirin may be preferred 7, 8

Common Pitfalls to Avoid

• Delaying aspirin therapy due to concerns about bleeding - the ECLAP study showed no significant increase in major bleeding with low-dose aspirin in PV patients 3, 5
• Using unnecessarily high doses of aspirin (>100mg daily), which increases bleeding risk without providing additional antithrombotic benefit 7, 8
• Focusing solely on phlebotomy without addressing other aspects of treatment (aspirin, cytoreductive therapy when indicated) 1
• Failing to address modifiable cardiovascular risk factors, which contribute significantly to thrombotic risk in PV 4