title: Prevalence of acquired von Willebrand syndrome during essential thrombocythemia: a retrospective analysis of 170 consecutive patients.
abstract: BACKGROUND
  The identification of patients with essential thrombocythemia (ET) who are at increased risk of acquired von Willebrand syndrome (AVWS) would likely facilitate individualization of treatment and improve its outcomes.
  
  
  OBJECTIVE
  The aim of the study was to determine the prevalence of AVWS in patients with ET and to verify whether individuals with and without this bleeding disorder differ in terms of their baseline clinical parameters.
  
  
  METHODS
  The study included 170 consecutive patients with ET. AVWS was diagnosed on the basis of reduced levels of von Willebrand factor and abnormal results of other routine tests. Patients with and without concomitant AVWS were compared in terms of their demographic characteristics, past and current medical histories, and laboratory parameters.
  
  
  RESULTS
  Concomitant AVWS was found in 34 patients (20%). Individuals with AVWS were diagnosed with ET at a significantly younger age than those without the syndrome. In addition, these patients significantly less often were in remission at the time of testing, had significantly higher erythrocyte and platelet counts, and showed abnormalities of the coagulation profile corresponding to defects of primary hemostasis as well as abnormal values of most parameters used i n the routine diagnosis of AVWS.
  
  
  CONCLUSIONS
  Even every fifth patient with ET may develop AVWS. Young age at diagnosis of ET and the lack of response to its previous treatment are potential risk factors for AVWS that should be considered during the management of the primary condition. All patients with ET and signs of a bleeding disorder, irrespective of the platelet count, should be tested for the presence of AVWS.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Mital
authors.forename: Witold
authors.initials: W
authors.lastname: Prejzner
authors.forename: Maria
authors.initials: M
authors.lastname: Bieniaszewska
authors.forename: Andrzej
authors.initials: A
authors.lastname: Hellmann
mesh_terms: D000328:Adult; D000368:Aged; D001780:Blood Coagulation Tests; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D013920:Thrombocythemia, Essential / Q000150:complications*; D014842:von Willebrand Diseases / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology