Background:
Essential thrombocythemia (ET) has a chronic course, but its main clinical features are thrombosis and hemorrhage. We evaluated the clinical features, including the vascular complications in patients with ET, during the disease courses and we determined the predictable risk factors for major vascular complications.
Methods:
From 1991 to 2004, the medical records for 69 patients with ET were retrospectively reviewed for evaluating the clinical features, including the vascular complications, and the predictable risk factors for major vascular complications were analyzed.
Results:
Major vascular thrombotic and hemorrhagic complications were observed in 16 patients (23.2%) and 6 patients (8.7%) at the time of diagnosis, and in 13 (18.8%) and 9 patients (13.0%) during follow-up. The incidence of major vascular thromboses in the older group (age ＞60 years) was higher than that in the younger group (≤60 years) (34.2% vs 9.7%, respectively, P=0.016) at the time of diagnosis. During follow-up, the major vascular thrombosis risk was increased in patients with a previous thrombosis history (37.5% vs 13.2%, respectively, P=0.029) and in patients with 2 or more combined cardiovascular risk factors (44.4% vs 15.0%, respectively, P=0.035). The probability of 10-year survival in patients with thrombo-hemorrhagic complications during the disease course was lower than that in patients without complication (60.5% vs 93.7%, respectively, P=0.046).
Conclusion:
Advanced age, a previous thrombosis history and the combined cardiovascular risk factors were the risk factors for major vascular thrombosis in patients with ET. Prevention of thrombo-hemorrhagic complications is the most important therapeutic goal. Treatment strategies according to risk factors ought to be prospectively investigated.

Keywords: Essential thrombocythemia, Thrombosis, Hemorrhage, Cardiovascular risk factors