IPSET-thrombosis Score Calculator

International Prognostic Score for Thrombosis in Essential Thrombocythemia (ET)

The IPSET-thrombosis applies to patients meeting WHO diagnostic criteria for ET.

2. Determine risk group and prognosis

ScoreRisk categoryAnnual thrombosis risk
0 - 1Low1.03%
3 - 6High3.56%


The IPSET-thrombosis model derives from multivariate analysis of 891 patients diagnosed with ET by WHO criteria within the preceding year, at one of seven centers. Most high-risk patients received cytoreductive therapy with hydroxyurea, anagrelide or busulfan, while most low-risk patients did not. Most patients (68%) received low-dose aspirin. The outcome variable was major thrombosis, defined as any of: venous thromboembolism, ischemic stroke, transient ischemic attack, myocardial infarction, or peripheral arterial thrombosis. The model was validated in an external cohort of 329 patients.1