Anticoagulation for Patients with Essential Thrombocythemia or Polycythemia Vera-Associated Venous Thromboembolism

Introduction: Essential thrombocytopenia (ET) and polycythemia vera (PV) are characterized by a high risk of thrombosis. Current guideline recommended low-dose aspirin for primary thromboprophylaxis in patients with ET or PV, but there is limited data describing the optimal anticoagulation strategies for managing venous thrombosis in these patients. We aimed to compare the effects of direct oral anticoagulant (DOAC) monotherapy versus DOAC-aspirin combined therapy on outcomes of patients with ET or PV-associated venous thrombosis.

Methods: We performed a retrospective, propensity score-matched cohort study by utilizing the TriNetX Analytics Network database. The TriNetX database is a collaborative research platform with de-identified electronic health records from more than 120 healthcare organizations. We included patients with a diagnosis of ET or PV who developed deep vein thrombosis (DVT) or pulmonary embolism (PE). Patients on a DOAC monotherapy were compared to those on a DOAC-aspirin combined therapy. The index date was defined as the start date of DOAC monotherapy or DOAC-aspirin combined therapy. Patients with atrial fibrillation before index date were excluded. The efficacy outcomes were recurrent venous thrombosis, which included PE and DVT, and arterial thrombosis comprising of ischemic stroke and acute myocardial infarction. The safety outcomes were gastrointestinal bleeding, intracranial bleeding, and hematuria.

Results: We identified 2839 patients eligible for inclusion. We matched 445 patients on a DOAC monotherapy to those on a DOAC-aspirin combined therapy. In Cox proportional hazards analyses, patients on a DOAC monotherapy had a similar efficacy in the prevention of recurrent venous thromboembolism (Hazard ratio (HR), 1.02 [95% CI: 0.67-1.54]), recurrent PE (HR, 1.13 [95% CI: 0.64-1.99]) and recurrent DVT (HR, 0.87 [95% CI: 0.49-1.56]) as well as ischemic stroke (HR, 0.68 [95% CI: 0.36-1.29]) and myocardial infarction (HR, 0.87 [95% CI: 0.42-1.80]) compared to patients on a DOAC-aspirin combined therapy. DOAC monotherapy was associated with lower risk of gastrointestinal bleeding (HR, 0.52 [95% CI: 0.28-0.97]) compare to DOAC-Aspirin combined therapy. There is no significant difference in the risk of intracranial bleed (HR, 0.95 [95% CI: 0.19-4.71]) and hematuria (HR, 1.02 [95% CI: 0.54-1.95]) between DOAC-aspirin combined therapy and DOAC monotherapy cohort.

Conclusion: DOAC monotherapy had a lower risk of gastrointestinal bleed but similar efficacy in the prevention of recurrent venous than DOAC-aspirin combined therapy among patients with ET or PV-associated venous thrombosis.