Study to Identify and Describe Predictive Factors for Thromboembolic Events in Patients With High-risk Polycythemia Vera

All patients are already on treatment with hydroxyurea or ruxolitinib at enrollment as per clinical practice and independently of their participation in this study. In addition, the follow-up visits and the evaluation procedures required in the study protocol correspond to current clinical practice. According to local regulations related to observational studies, assessments such as blood tests are justified by the purpose and rationale of the study (i.e., the identification of possible predictive factors of TEs) and are considered current clinical practice. Data related to other procedures will be collected only if such procedures are performed as per clinical practice but are not required otherwise. Patients in both cohorts will be followed for 3 years after enrollment and will have visits at Months 6, 12, 18, 24, 30 and 36. A time window of ± 1 month is permitted for all visits.