PB1193 - Prevalence and clinical characteristics of patients with acquired von Willebrand syndrome and essential thrombocythemia: retrospective analysis of 40 patients.

Background: Approximately 1 in 5 patients with essential thrombocythemia (ET) may develop acquired von Willebrand syndrome (AVWS), due to proteolytic loss of high molecular weight multimers of von Willebrand factor (VWF). Given the potential hemorrhagic complications that significantly worsen quality of life, it is essential to identify these patients early.

Aims: To determine the prevalence of AVWS in patients with ET and verify whether individuals with and without this bleeding disorder differ in terms of their baseline clinical parameters.

Methods: A total of 40 patients with a diagnosis of ET have been analyzed retrospectively and single-centerly from 05-2018 to 12-2023. Patients with and without concomitant AVWS were compared in terms of their demographic characteristics, past and current medical history, and laboratory parameters. Clinical and analytical data were collected.

Results: The median age was 72 years (range: 32-90 years) with a slight predominance of females (55%). 50% had at least one identified cardiovascular risk factor. Concomitant AVWS was found in 6 patients (15%), none at the time of diagnosis. People with AVWS were diagnosed with ET at a significantly younger age than those without the syndrome (median AVWS: 52 years, range: 32-60. 95% CI: 3.55-32.37; p< 0.001), received less treatment with hydroxyurea (a predictable fact given the recommendations of the Spanish treatment guidelines) and a higher platelet count at the time of diagnosis (median AVWS 810x10^3/ul vs. non-AVWS: 566x10^3/ul; p< 0.001). There were no statistically significant differences regarding sex, alterations in the basic hemostasis profile, associated molecular alteration or clinical manifestations (all patients with AVWS expressed minor mucocutaneous symptoms at diagnosis).

Conclusion(s): A younger age at diagnosis and poor control of the platelet count constitute the highest risk profile for presenting AVWS, so it is essential to monitor these patients for the presence of this complication.