How should I approach the management of a patient with Polycythaemia Vera who presents with recurrent thrombosis?

Management of a patient with Polycythaemia Vera (PV) presenting with recurrent thrombosis involves:

• Maintaining haematocrit below 0.45 through therapeutic venesection, adjusting volume and frequency based on patient size and tolerance, to reduce blood viscosity and thrombotic risk.
• Prescribing low-dose aspirin (75 mg daily) unless contraindicated, to reduce thrombotic events.
• Initiating pharmacological cytoreductive therapy as the patient is at high risk due to recurrent thrombosis. The first-line agent is usually hydroxycarbamide, especially in patients over 60 years or with a history of thrombosis.
• Considering alternative cytoreductive agents such as interferon alfa or ruxolitinib if hydroxycarbamide is contraindicated, not tolerated, or ineffective.
• Monitoring and titrating treatment over weeks to maintain haematocrit <0.45 and control blood counts, as resistance to hydroxycarbamide is linked to worse outcomes.
• Addressing additional risk factors such as elevated white blood cell or platelet counts, symptomatic splenomegaly, or frequent venesection requirements, which may also prompt cytoreductive therapy.
• Ensuring specialist secondary care involvement for management, including patient education about risks and implications of PV.

In cases of recurrent thrombosis despite anticoagulation, review adherence and consider intensifying or changing anticoagulant therapy per venous thromboembolism guidelines, alongside PV-specific treatment.