Similarity in joint function limitation in Type 3 von Willebrand's disease and moderate haemophilia A

Summary Type 3 von Willebrand's disease ( VWD ) is a rare bleeding diathesis with complete or near complete deficiency of von Willebrand factor ( VWF ) and low factor VIII ( FVIII ) levels. In contrast, only FVIII is decreased in haemophilia A ( HA ). Both disorders are complicated by arthropathy. The purpose of this study was to further clarify the roles of FVIII and VWF : Antigen ( VWF :Ag) in joint range of motion ( ROM ) loss over time. We compared joint ROM loss and other bleeding manifestations in 100 Type 3 VWD subjects ( FVIII < 5%) and 1814 moderate HA subjects ( FVIII 1–5%) within the U.S. Universal Data Collection ( UDC ) database. High rates of bleeding were reported at baseline. During follow‐up, moderate HA patients reported a joint (46% vs. 34%, P  < 0.0001) or muscle bleed (27% vs. 16%, P  < 0.0001) in a higher proportion of visits than VWD patients. Other bleeds, including mucosal, were reported in a greater proportion of visits among patients with Type 3 VWD than among those with HA (49% vs. 32%, P  < 0.0001). Multivariate analysis revealed no difference in joint ROM loss over time in the Type 3 VWD vs. moderate HA populations. A higher FVIII level was protective in both VWD and HA ( P  < 0.001). Our findings support the hypothesis of primacy of the FVIII level in determining risk of joint haemorrhage, and may help target therapy in Type 3 VWD and moderate HA to prevent joint disability.