Factors Related to the Development of Acquired Von Willebrand Syndrome in Patients with Essential Thrombocythemia and Polycythemia Vera

Objective: We characterized acquired von Willebrand syndrome (AVWS) among essential thrombocythemia (ET) and polycythemia vera (PV) patients. Methods: A review of patients with ET or PV evaluated for AVWS. Results: Of 116 patients with ET, 64 (55%) developed AVWS; of 57 with PV, 28 (49%) developed AVWS. Median platelet counts of ET and PV patients who developed AVWS were 920 X 10 9 /L and 679 X 10 9 /L, respectively (P=0.01). Of patients who developed AVWS, 69.5% had platelet counts below 1000 X 10 9 /L. Bleeding was more common in patients with AVWS, among both ET and PV patients (P 9 /l, P=0.05). In multivariable analysis, age (β=0.26, P=0.002), platelet count (β=-0.38, P Conclusion: Among ET and PV patients, AVWS was common and associated with higher bleeding rates and higher platelet count; nonetheless, most AVWS patients had platelet counts under 1000 X 10 9 /L. Thus, AVWS screening should be included in routine assessment of ET and PV patients. Among ET patients, JAK2 V617F was a main driver for the development of AVWS. Disclosures No relevant conflicts of interest to declare.