Von Willebrand disease (VWD) is an inherited bleeding disorder that is caused by deficiency or dysfunction of von Willebrand factor (VWF), a plasma protein that mediates the initial adhesion of platelets at sites of vascular injury and also binds and stabilizes blood clotting factor VIII (FVIII) in the circulation. Therefore, defects in VWF can cause bleeding by impairing platelet adhesion or by reducing the concentration of FVIII.
VWD is a relatively common cause of bleeding, but the prevalence varies considerably among studies and depends strongly on the case definition that is used. VWD prevalence has been estimated in several countries on the basis of the number of symptomatic patients seen at hemostasis centers, and the values range from roughly 23 to 110 per million population (0.0023 to 0.01 percent).
The prevalence of VWD also has been estimated by screening populations to identify persons with bleeding symptoms, low VWF levels, and similarly affected family members. This population-based approach has yielded estimates for VWD prevalence of 0.6 percent, 0.8 percent, and 1.3 percent—more than two orders of magnitude higher than the values arrived at by surveys of hemostasis centers.
The discrepancies between the methods for estimating VWD prevalence illustrate the need for better information concerning the relationship between VWF levels and bleeding. Many bleeding symptoms are exacerbated by defects in VWF, but the magnitude of the effect is not known. For example, approximately 12 percent of women who have menstrual periods have excessive menstrual bleeding. This fraction is much higher among women who have VWD, but it also appears to be increased for women who have VWF levels at the lower end of the normal range. Quantitative data on these issues would allow a more informed approach to the diagnosis and management of VWD and could have significant implications for medical practice and for public health.
Aside from needs for better information about VWD prevalence and the relationship of low VWF levels to bleeding symptoms or risk, there are needs for enhancing knowledge and improving clinical and laboratory diagnostic tools for VWD. Furthermore, there are needs for better knowledge of and treatment options for management of VWD and bleeding or bleeding risk. As documented in this VWD guidelines publication, a relative paucity of published studies is available to support some of the recommendations which, therefore, are mainly based on Expert Panel opinion.
Guidelines for VWD diagnosis and management, based on the evidence from published studies and/or the opinions of experts, have been published for practitioners in Canada, Italy, and the United Kingdom, but not in the United States. The VWD guidelines from the U.S. Expert Panel are based on review of published evidence as well as expert opinion. Users of these guidelines should be aware that individual professional judgment is not abrogated by recommendations in these guidelines.
These guidelines for diagnosis and management of VWD were developed for practicing primary care and specialist clinicians—including family physicians, internists, obstetrician-gynecologists, pediatricians, and nurse-practitioners—as well as hematologists and laboratory medicine specialists.
For a full guide published by NIH click here. This guide is well worth the time to read if you feel or have VWD!