PREVALENCE OF VON-WILLEBRAND DISEASE IN CHILDREN - A MULTIETHNIC STUDY

Objective: Von Willebrand disease (vWD) was thought to be a rare disor der until a recent survey reported a prevalence of 0.8% in an ethnical ly homogenous community in northern Italy. The purpose of this study w as to determine the prevalence of vWD in an ethnically heterogenous po pulation. Methods: Von Willebrand factor (vWF) was measured by the ris tocetin cofactor method in 600 healthy children, aged 2 to 18 years, s een for routine school physical examinations in a three-state region. Personal and family bleeding symptoms were determined by questionnaire . The diagnosis of vWD required a personal history of bleeding symptom s, an abnormal vWF activity concentration, and a family history of at least one immediate family member with bleeding symptoms. Results: A t otal of 315 subjects were white, 212 were black, 16 were Hispanic, 10 were from other groups, and 47 were biracial. Eight subjects (four bla ck, four white) met the criteria for vWD, for a prevalence of 1.3%. Se ven subjects with vWD had blood group O (mean vWF = 32 U/dl; range, 10 to 42 U/dl), and one had blood group A (vWF = 41 U/dl). Children who had blood group 0 had significantly (p < 0.001) lower vWF activities ( median, 83 U/dl, range, 43 to 162 U/dl) than those from non-O blood gr oups (median, 98 U/dl; range, 51 to 190 U/dl). There were no significa nt differences in vWF activity by ethnicity. The vWF activity was sign ificantly (p < 0.02) greater for boys than girls in both blood groups. Conclusion: Von Willebrand disease is the most common congenital hemo static disorder; its high prevalence is not limited to one ethnic grou p.