Risk of Bleeding in Essential Thrombocythemia Patients with Extreme Thrombocytosis
Key Points
No difference in the cumulative incidence of bleeding in ET patients with vs. without ExT
There is no clear indication for cytoreduction to decrease bleeding risk based on a platelet threshold of 1 million alone
About 25% of essential thrombocythemia (ET) patients present with extreme thrombocytosis (ExT), defined as having a platelet count ≥1000 x 10^9/L. ExT patients may have an increased bleeding risk associated with acquired von Willebrand syndrome. We retrospectively analyzed the risk of bleeding and thrombosis in ExT vs. non-ExT ET patients at Dana Farber Cancer Institute and Massachusetts General Hospital from 2014-2022 to inform treatment decisions. We abstracted the first major bleed, clinically relevant non-major bleed (CRNMB), and thrombotic event from medical records. We identified 128 (28%) ExT patients and 323 (72%) non-ExT patients. Cumulative incidence of bleeding was not different in ExT vs. non-ExT patients (21% vs. 13%, p=0.28 for major bleed; 16% vs. 15%, p=0.50 for CRNMB). Very low and low thrombotic risk ExT patients were more likely to be cytoreduced compared to very low and low risk non-ExT patients (69% vs. 50%, p=0.060 for very low risk; 83% vs. 53%, p=0.0059 for low risk). However, we found no differences in bleeding between ExT and non-ExT patients when restricting the risk of bleed from diagnosis to cytoreduction start date (28% vs. 19%, p=0.29 for major bleed; 24% vs. 22%, p=0.75 for CRNMB). Cumulative incidence of thrombosis was also not different between ExT and non-ExT patients (28% vs. 25%, p=0.98). This suggests that cytoreduction may not be necessary to reduce bleeding risk based only on a platelet count of 1 million. We identified novel risk factors for bleeding in ET patients including diabetes mellitus and the DNMT3A mutation.
Rathnam K Venkat, Robert A Redd, Amyah C. Harris, Martin J Aryee, Anna E. Marneth, Baransel Kamaz, Chulwoo J Kim, Mohammed Wazir, Lachelle D. Weeks, Maximilian Stahl, Daniel J DeAngelo, R. Coleman Lindsley, Marlise R. Luskin, Gabriela S Hobbs, Joan How
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