Polycythemia vera (PV) is associated with increased risk of thrombosis and hemorrhage. Aspirin, recommended for primary thromboprophylaxis, is often combined with anticoagulants during management of acute thrombotic events. The safety of dual antiplatelet and anticoagulant therapy is not established in PV. In a prospective, observational study, 2510 patients with PV were enrolled at 227 sites in the United States. Patients were monitored for the development of hemorrhage and thrombosis after enrollment. A total of 1602 patients with PV received aspirin with median (range) follow-up of 2.4 (0-3.6) years. The exposure-adjusted rate of all hemorrhages in patients receiving aspirin alone was 1.40 per 100 patient-years (95% confidence interval [CI]: 0.99-1.82). The combination of aspirin plus anticoagulant was associated with an incidence of hemorrhage of 6.75 per 100 patient-years (95% CI: 3.04-10.46). The risk of hemorrhage was significantly greater in patients receiving the combination of aspirin and anticoagulant compared with aspirin alone (total hemorrhages, hazard ratio [HR]: 5.83; 95% CI: 3.36-10.11; P
Clinical and Disease Characteristics From REVEAL at Time of Enrollment (Baseline): Prospective Observational Study of Patients With Polycythemia Vera in the United States
