Patients with myeloproliferative neoplasms (MPNs), polycythemia vera, essential thrombocythemia, and primary myelofibrosis, have an increased risk of thrombosis. Risk of recurrent thrombosis can be reduced with antithrombotic therapy and/or cytoreduction, but the optimal long-term management in patients with MPN with a history of venous thromboembolism (VTE) is unknown, and clinical practice is heterogeneous. We performed a systematic review and meta-analysis of randomized trials and observational studies evaluating anticoagulant and/or antiplatelet therapy, with or without cytoreduction, in MPN patients with a history of VTE. A total of 5675 unique citations were screened for eligibility. No randomized trials were identified. Ten observational studies involving 1295 patients with MPN were included in the analysis. Overall, 23% had an arterial or recurrent venous thrombotic event on follow-up. The recurrence risk was lowest for patients on oral anticoagulation plus cytoreduction (16%); 55 of 313 (18%) with vitamin K antagonists (VKA) and 5 of 63 (8%) with direct oral anticoagulants (DOACs). In 746 analyzed patients, the risk of recurrent VTE ranged up to 33% (median 13%) and was low in 63 DOAC plus cytoreductiontreated patients (3.2%). All types of antithrombotic treatments were associated with a lower risk of recurrent VTE when combined with cytoreduction. Most studies had a high risk of bias, whereas clinical and statistical heterogeneity led to inconsistent and imprecise findings. In summary, evidence on the optimal antithrombotic treatment of VTE in patients with MPN is based on observational studies only with low certainty for all strategies. Our data suggest that a combination of anticoagulation and cytoreduction may provide the lowest recurrence risk.
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Conflict-of-interest disclosure: F.W.G.L. received research support from CSL Behring, Shire/Takeda, uniQure, and Sobi, not related to this study; is a consultant for uniQure, Novo Nordisk, and Shire/ Takeda, of which the fees go to the institution; has received a travel grant from Sobi; and is also a Data Safety Monitoring Board member for a study by Roche. B.J.B. received research grants from Sanquin, Novartis, and GBT and joined advisory boards of Novartis, Celgene, Amgen, GBT, and CSL Behring. P.A.W.t.B. joined advisory boards of Novartis and Celgene. S.M. reports grants and fees paid to her institution from GSK, BMS/Pfizer, Aspen, Daiichi Sankyo, Bayer, Boehringer Ingelheim, Sanofi, and Portola. M.N.L. reports grants and fees paid to her institution from GSK, BMS/Pfizer, Bayer, and Novo Nordisk. The remaining authors declare no competing financial interests.
© 2021 by The American Society of Hematology.