Increased risk of thrombosis in JAK2 V617F-positive patients with primary myelofibrosis and interaction of the mutation with the IPSS score

Thrombosis remains a major unmet need in polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), accounting for three to four-fold higher probability of risk compared to controls [1]. In PMF, this risk is poorly characterized given that, unlike PV and ET, death due to disease progression and/or evolution to leukemia represents a competing risk that significantly overwhelms that attributable to vascular complications [2–5]. We analyzed a large cohort of PMF patients enrolled in the European ERNEST registry with the aim to identify patients at higher risk in which anti-thrombotic prophylaxis could be suggested. Primary prophylaxis with aspirin is debated in PMF and, since thrombosis is not considered a major issue, some experts prescribe this agent only as a secondary prophylaxis after an arterial event [6].