Exploratory Multi-centre Trial In Patients With ET Treated With XAGRID®

Inclusion criteria

• Patients must be able to understand and willing to participate in the study, and provide a personally dated and signed written informed consent form.
• Patients must have a confirmed diagnosis of ET according to the World health Organisation's criteria.
• ET patients who are uncontrolled, in the Investigator's opinion, by first-line (or previous) cytoreductive treatment for efficacy or tolerance reasons.
• Patients who have either commenced treatment with anagrelide hydrochloride in the last 7 days or for whom a decision has been documented to commence treatment with anagrelide hydrochloride

Exclusion criteria

• Patients for whom treatment with anagrelide hydrochloride is contraindicated, according to the current XAGRID SmPC.
• Known or suspected intolerance or hypersensitivity to the product, closely related compounds, or any of the stated ingredients.
• Patients participating in an interventional research study.
• Patients on combination therapy or for whom there is an intention to treat with other cytoreductive agents e.g., hydroxyurea, interferon. Patients can however use aspirin and other anti-aggregatory products at the Investigator's discretion.