Factors related to the development of acquired von Willebrand syndrome in patients with essential thrombocythemia and polycythemia vera

Abstract 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 920×10 9 /L and 679×10 9 /L, respectively (P=0.01). Of patients who developed AVWS, 69.5% had platelet counts below 1000×10 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, younger age (P=0.002), platelet count (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 1000×10 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.