Longitudinal bleeding assessment in von Willebrand disease utilizing an interim bleeding score

Assessment of bleeding phenotype is critically important in the diagnosis of von Willebrand disease (VWD). Despite advances in bleeding assessment tools (BATs), standardized tools to evaluate bleeding following diagnosis (interim bleeding) are lacking. We assessed the clinical utility of an interim bleeding protocol in a multicenter, international study involving patients with VWD. The enrolment ISTH BAT formed the original bleeding score (0 BS). At follow‐up, the International Society on Thrombosis and Haemostasis BAT was repeated but included only interval bleeding (Interim BS, 1 BS). Both scores were annualized (0 BS/yr, 1 BS/yr). BS were analyzed by VWD subtype, plasma VWF level, sex, and age. Interim BS discriminated by subtype, with significantly increased 0 BS and 1 BS in patients with type 3 VWD. In patients with type 1 VWD, a positive or negative 0 BS did not predict future bleeding, with similar 1 BS/yr (median 1.0 vs. 0.7, p= .2). Despite significantly higher 0 BS in females with type 1 VWD than males (median 7 vs. 5, p= .0012), 1 BS were not significantly different (median 4 vs. 4, p= .16). While 0 BS were lower in children than adults with type 1 VWD, interim BS were similar (median 5 vs. 3, p= .5; 1BS/yr, median 1 vs. 0.8, p= .7). Interestingly, in those with plasma von Willebrand factor:ristocetin cofactor levels >50 IU/dl, interim BS rates were similar to those 30–50 IU/dl (1 BS/yr 0.8 vs. 1.3, p= .5). This study provides both a new approach to longitudinal bleeding assessment and insights into the evolution of bleeding in VWD.