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Von Willebrand disease (VWD)—a disorder due to dysfunctional or deficient von Willebrand factor (VWF)—is the most common inherited disorder of hemostasis and is prevalent in approximately 1% of the total worldwide population,1,2 although the prevalence of symptomatic VWD is about 10 times lower.3
The International Society on Thrombosis and Haemostasis (ISTH)4 classified VWD into three primary categories: type 1, type 2, and type 3. Type 2 is further divided into four sub-categories: type 2A, type 2B, type 2M, and type 2N. Type 1 is the mildest form of VWD and accounts for approximately 75% of VWD.5 It is defined by a partial quantitative deficiency in VWF and it is estimated that 56.3 and 30.7% of type 1 patients suffer from epistaxis and menorrhagia, respectively (see Table 1). Combined, type 2 accounts for an estimated 25% of VWD patients, and is caused by qualitative abnormalities in VWF. The most common bleeding symptoms in type 2 VWD are epistaxis (63%) and bleeding after dental extraction (39%) (see Table 1). Type 3 is the most severe form of the disease and the least common, with an incidence of 0.55–3.2 per million in Western countries.6 Type 3 is characterized by low or no detectable VWF in plasma and is associated with the most severe bleeding symptoms. Epistaxis occurs in 74% of type 3 patients, 52% suffer bleeding after dental extraction, and joint bleeding occurs in 42% of type 3 cases (see Table 1).2
Joint disease is one of the most severe complications of inherited bleeding disorders in general; however, the exact prevalence of this complication in VWD is still unclear. Lak et al. reported that 37% of 385 Iranian children with type 3 VWD had at least one episode of joint bleeding.7 In the US, a Universal Data Collection Program (UDCP) has been established to collect clinical data from Hemophilia Treatment Centers (HTCs). To date, the UDCP has reported that 14% of type 3 VWD patients suffered from target joint complications and 28.4% had limitations to movement because of joint complications.8 Target joint bleeds are less common in VWD patients with type 1 and 2 disease, at rates of 1.4 and 1.1%, respectively.