[Clinical characteristics and risk factors for major thrombosis in 604 Chinese patients with low-risk essential thrombocythemia].

OBJECTIVE:To analyze clinical and molecular characteristics of low-risk essential thrombocythemia (ET) in a large cohort of Chinese patients and to explore risk factors for major thrombosis and treatment strategies. METHODS:Medical records of patients with an initial diagnosis of ET from March 1982 to May 2012 in our hospital were retrospectively analyzed. RESULTS:A total of 604 low-risk ET patients were enrolled with a median follow-up of 49 months (range:0-338). 43(7.1%) patients experienced major thrombotic events. Cox proportional hazards regression revealed JAK2 V617F mutation (HR=2.279; P=0.035) and cardiovascular risk factors (CVF) (HR=2.541; P=0.006) to be risk factors for total thrombotic events, while only CVF (HR=2.633; P=0.008) was risk factor for arterial thrombosis. None of the evaluated factors was related to venous thrombosis. Patients with both JAK2 V617F mutation and CVF had a worse thrombosis- free survival than those with only one risk factor (P<0.05). In patients with JAK2 V617F or CVF alone, antiplatelet treatment (P=0.016) significantly decreased the risk of thrombosis, while those with both JAK2 V617F and CVF could benefit from cytoreductive agents (P=0.018). CONCLUSION:Chinese low-risk ET patients have a lower risk of thrombosis than Caucasian low-risk ET patients. JAK2 V617F mutation and CVF are the most significant risk factors for thrombosis. Existence of both risk factors further increases the thrombotic risk. Treatment strategies on low-risk ET patients should be made based on presence or absence of risk factors.