FVIII/VWF ratio is not a reliable predictor of VWD in children.

ABSTRACT

Adults with von Willebrand Disease (VWD) are known to have a ratio of factor VIII activity (FVIIIC) to von Willebrand factor antigen (VWFAg) greater than 1. We, however, noted healthy children with ratios that are unexpectedly high. Though the FVIIIC/VWFAg ratio differs significantly between healthy children and VWD patients in some age groups, the substantial overlap of observed ranges suggests that a ratio threshold-based screening approach alone cannot reliably discriminate between these groups. The diagnostic performance of this ratio is poor for VWD in children, which may decrease its value as a screening tool in the pediatric population.