Thromboembolic Events in Polycythaemia Vera Patients:An Audit of the Hungarian Philadelphia Negative Chronic Myeloproliferative Neoplasia Register

Objective: The Hungarian National Registry for Philadelphia chromosome negative myeloproliferative neoplasms was used to assess the clinical characteristics of Hungarian patients with polycythemia vera.

Methods: Data from 351 JAK2 V617F-positive patients diagnosed with PV were collected online from 15 haematology centres reporting clinical characteristics, therapeutic interventions, venous and arterial thromboembolic events, and myelofibrotic or leukaemic transformations. Vascular events (thromboembolic and haemorrhagic) were evaluated before and after diagnosis based upon the Landolfi risk assessment scale.

Results: TE were reported on 116 occasions (106 patients) before diagnosis and 152 occasions (102 cases) during follow-up. Compared to before diagnosis, after diagnosis frequency of major arterial events decreased from 11.7% to 2.6% (p<0.0001), and minor venous events increased from 2.0% to 14.2% (p<0.0001); there was no significant change in number of major venous events (from 6.3% to 8.8%; p=0.25) or minor arterial events (from 13.1% to 17.7%; p=0.12). Bleeding events were recorded in 6.4% of patients. Despite treatment, 42.2% of patients with prior thromboembolic events had recurrent thromboembolic complications. After diagnosis age and prior history of thromboembolic events were independent risk factors for arterial events, and white blood cells and diabetes for venous events. Hydroxyurea use in the low+moderate risk Landolfi group slightly, but not significantly, increased thromboembolic event risk (p=0.74).

Conclusions: This registry enables characterisation of patients with polycythemia vera. Data suggest the need for accuracy of diagnostic criteria and compliance with risk-adapted therapeutic guidelines.