Recurrent Venous Thrombosis in Patients with Polycythemia Vera and Essential Thrombocythemia

PurposeThe risk of recurrent venous thromboembolism (VTE) in patients with polycythemia vera and essential thrombocythemia has been scarcely addressed, and whether long-term oral anticoagulant treatment or acetylsalicylic acid should be recommended after first occurrence of deep venous thrombosis (DVT) is unknown. This multicenter cohort study was aimed to assess the rate of recurrent VTE in patients with polycythemia vera or essential thrombocythemia in comparison with a control group of individuals with previous VTE and without neoplastic diseases.Patients and MethodsWe retrospectively estimated the rate of recurrence in 79 patients with myeloproliferative disorders (MPDs; polycythemia vera/essential thrombocythemia, 45/34) and with a previous proximal DVT. Patients were divided into 2 groups. The first comprised 41 patients who received acetylsalicylic acid after 6 months of oral anticoagulant treatment. The second group was composed of 38 patients given long-term oral anticoagulant treatment without acetylsalicylic acid. The majority of patients were treated with cytotoxic drugs. The results were compared with the recurrences seen in 176 patients without cancer with previous proximal DVT given short-term oral anticoagulant treatment.ResultsIn the patients with polycythemia vera and essential thrombocythemia, the rate of recurrent DVT was higher in the group receiving acetylsalicylic acid (32%) compared with the group on oral anticoagulant treatment (16%), although not statistically significant. The rate of recurrent DVT in MPD cases receiving acetylsalicylic acid was quite similar to that of patients without cancer (33%). The cumulative probability of recurrent VTE indicated a trend of fewer events in the MPD cases on long-term oral anticoagulant treatment. In the patients with MPDs, the incidence of major bleeding during oral anticoagulant treatment or acetylsalicylic acid was 1% and 0.5% patient-years (years of observation), respectively.ConclusionThis retrospective analysis would suggest a long-term oral anticoagulant treatment after a first DVT in patients with polycythemia vera and essential thrombocythemia. However, this indication should be weighed against the risk of major hemorrhagic events that seems lower during long-term prophylaxis with acetylsalicylic acid. Therefore, a prospective clinical trial comparing acetylsalicylic acid in patients with polycythemia vera and essential thrombocythemia with oral anticoagulant treatment in the prevention of recurrent VTE is warranted.