JAK2V617F allele burden and thrombosis: A direct comparison in essential thrombocythemia and polycythemia vera
Received 20 April 2009; received in revised form 16 June 2009; accepted 17 June 2009. published online 25 June 2009.
Objective
A direct comparison of the incidence and risk factors of major thrombosis in essential thrombocythemia (ET) and polycythemia vera (PV) according to their respective JAK2V617F allele burden is the object of this study.
Materials and Methods
We compared the rate (%/patients/year) of major thrombosis in 867 ET patients (57% JAK2V617F) with that of 415 PV patients (all JAK2V617F) and examined risk factors.
Results
Patients with ET wild-type, ET V617F, and PV showed a rate of thrombosis of 1.4%, 2.1%, and 2.7%/patients/year, respectively. The latter was found to progressively increase according to time of diagnosis. Actuarial probability of arterial and venous thrombosis in the first 5 years of diagnosis was roughly similar in the three groups. While in the subsequent periods, the curves of mutated ET patients diverged from wild-type, and after 10 to 15 years the ET-mutated arm approached PV.
Conclusion
These findings support the concept of a continuum between ET JAK2 mutated and PV, not only in reference to the hematological phenotype, but also in terms of vascular events.
aHematology Department, Ospedali Riuniti di Bergamo, Bergamo, Italy
bHematology Department, Università degli Studi di Firenze, Florence, Italy
Offprint requests to: Tiziano Barbui, M.D., Ospedali Riuniti di Bergamo, Largo Barozzi 1 24128 Bergamo, Italy
ABSTRACT