Incidence, Characteristics, and Management of Venous Thrombosis in Adult Patients With Immune Thrombocytopenia: Results From the Multicenter, Prospective Registry CARMEN-France.

Adult patients with immune thrombocytopenia (ITP) have an increased risk of venous thrombosis as compared to the general population. The management of ITP in the context of anticoagulation is challenging. We conducted an observational study in the prospective, multicenter, national CARMEN-France registry. Adult patients with newly diagnosed ITP between June 2013 and May 2022 were selected. We assessed the cumulative incidence of venous thrombosis during follow-up with death as a competing event, described these events, and assessed patient outcomes depending on management strategies, with a focus on thromboses that occurred during treatment with thrombopoietin receptor agonists (TPO-RA). Among the 1303 patients selected for this study, 53 experienced venous thrombosis. The cumulative incidence of venous thrombosis was 2.6% (95% CI: 1.8-3.7) at 1 year and 8.6% (95% CI: 5.8-12.0) at 5 years. In patients exposed to TPO-RA, the cumulative incidence was 9.3% (95% CI: 6.2-13.2) and 13.4% (95% CI: 8.6-19.2) at 1 and 5 years of exposure, respectively. Patients who experienced thrombosis were older, had more frequently a history of venous thrombosis and secondary ITP, a more severe ITP, and were more frequently treated with TPO-RAs. Twenty (37.7%) of the 53 events were atypical, including five cerebral venous thromboses. Four patients died, and seven experienced major bleeding. The analysis of different managements of ITP after the thrombotic event suggested that the safest strategy was to promptly control ITP to enable early anticoagulation, including using TPO-RAs. Long-term anticoagulation therapy should be considered in patients treated with TPO-RAs and persistent risk factors for thrombosis.