Von Willebrand Disease in the Netherlands
Von Willebrand Disease in the Netherlands
The primary aim of this study is to prospectively investigate the current bleeding tendency
 of children and adults with VWD.
Von Willebrand disease (VWD) is the most common inherited bleeding disorder, and is
 characterized by a defective platelet adhesion and aggregation. VWD is caused by a reduced
 (type 1), an abnormal function (type 2) or a complete absence (type 3) of von Willebrand
 factor (VWF).

 In recent years, large retrospective cohort studies have provided valuable insights on the
 clinical presentation, bleeding phenotype, quality of life, diagnostics, genetics and
 treatment of patients with VWD. One of these large studies is the von Willebrand in the
 Netherlands (WiN) study, which is a nationwide cross sectional study of moderate and severe
 von Willebrand disease patients, that was initiated in 2007. Over 800 VWD patients were
 included in the WiN study, which was about 80% of all known VWD patients in the Netherlands.
 Although the WiN study and large retrospective studies in other countries provided important
 insights in understanding VWD, some significant challenges remain and large prospective
 studies are lacking to provide answers.

 All large retrospective cohort studies have assessed the bleeding phenotype of patients with
 VWD using bleeding scores or retrospective questionnaires. Bleeding scores calculate the sum
 of all bleeding episodes during lifetime. Therefore, they provide useful information on the
 bleeding tendency during lifetime. However, bleeding scores do not provide information on the
 change of bleeding tendency. If a patient had a period in his or her lifetime in which he or
 she had many bleeding episodes, then the bleeding score is high. Though, the patient could
 have had those bleeds 30 years ago and did not have a bleeding episode since then. Therefore,
 bleeding scores do not provide information on the current bleeding phenotype of VWD patients.
 Furthermore, previous studies provided limited information on the frequency of mild
 bleedings, like gum bleeding or epistaxis, that occur in daily life but do not require
 therapy. Nevertheless, these bleeding episodes can cause a major impairment in quality of
 life. This is especially important in children, because school-going children with VWD have a
 lower quality of life and have a different bleeding tendency, characterized by more cutaneous
 bleeding (81%), oropharyngeal bleeding (64%) and epistaxis (56%).

 Therefore, the primary aim of this study is to prospectively investigate the current bleeding
 tendency of children and adults with VWD.
Inclusion Criteria:

 -  Historically lowest VWF:Ag and/or VWF:RCo and/or VWF:CB ≤ 0.30 IU/mL and/or FVIII:C ≤
 0.40 IU/mL

 -  Treatment at a Hemophilia treatment center in the Netherlands

 -  All types of VWD

 -  All ages

 Exclusion Criteria:

 - Other known bleeding disorders present.