Evaluation of thrombotic events in patients with immune thrombocytopenia

Immune thrombocytopenia (ITP) has been reported to be associated with thrombotic events. The incidence of thrombosis in 303 newly diagnosed ITP patients in our institute between 2000 and 2016 was retrospectively reviewed. During a median follow-up of 3.6 years, 16 thrombotic events (12 arterial and four venous) occurred. The median platelet count at thrombotic events was 102 × 10⁹/l. At 10 years, the cumulative thrombosis incidence was 10%. A univariate analysis showed that smoking, hypertension, male gender, a history of thrombosis, and atrial fibrillation (Af) were significantly associated with the occurrence of thrombosis, and a multivariate analysis identified smoking and Af as independent risk factors. The thrombotic risk was not increased by lupus anticoagulant positivity or ITP treatment. At 5 years, the cumulative incidence of bleeding and overall survival probability was 5.6% and 92%, respectively. This study demonstrates that smoking and Af were associated with an increased risk of thrombosis. Previously identified risk factors were not confirmed in these Japanese ITP patients.