How I treat von Willebrand disease

Classification of inherited von Willebrand disease and implications in clinical practice

Von Willebrand disease (VWD) is the most common inherited bleeding disorder and is caused by quantitative or qualitative deficiencies in von Willebrand factor (VWF). Diagnosis relies on clinical characteristics, such as bleeding symptoms and a family history of bleeding symptoms, and laboratory tests confirming reduced levels or activity of VWF. Several types of VWD have been identified that have distinct pathology, phenotype, and response to therapy. No single test provides sufficient information to classify the disorder, and multiple assays are needed. These assays can determine whether bleeding is caused by quantitative (types 1 and 3) or qualitative (type 2) deficiency in VWF activity. The presence or absence of high-molecular weight multimers of VWF can distinguish between types 2M and 2A VWD, respectively. Higher affinity for platelet glycoprotein Iba receptors suggests type 2B, and poor affinity for factor VIII indicates type 2N VWD. Other tests, including molecular diagnostic techniques, may be used to confirm the diagnosis. Despite the apparent complexity surrounding the classification of VWD, accurate classification is achievable using the appropriate combination of laboratory assessments. Correct classification is essential to the management of patients with VWD because therapeutic decisions often depend on the specific type of disease.

Optimizing treatment of von Willebrand disease by using phenotypic and molecular data

The wide clinical spectrum of von Willebrand disease (VWD), its complex pathophysiology and its classification into distinct quantitative (type 1 or type 3) and qualitative (type 2) types with further subtle distinctions have prevented most clinicians from establishing a straightforward approach to diagnosing and treating this inherited bleeding disorder. The results of studies involving large cohorts of patients with a wide range of bleeding manifestations and variable von Willebrand factor (VWF) reduction have recently become available. These data have allowed the proposal of minimal criteria for a clinically useful diagnosis and for differentiating patients with mild VWD from subjects with borderline or only slightly reduced VWF levels who will not benefit from a specific diagnosis. These criteria are based on measurement of VWF ristocetin cofactor (VWF:RCo), VWF antigen (VWF:Ag), factor VIII and a standardized bleeding score (BS). Demonstration of the inheritance of the disorder could help to classify patients for whom insufficient hemostatic challenges may produce a falsely reassuring BS (like in children). Using this approach, mild VWD appears to be mostly composed of type 1 cases. Complemented by the results of desmopressin trial infusion, these parameters form the basis for a clinically oriented classification of all forms of VWD and may be useful for selecting the best treatment according to the severity of the disease. Although few molecular data have revealed practical utility, there is no doubt that the clarification of the molecular pathophysiology of VWD has allowed the unification of this complex disorder into a simple conceptual framework. This framework underlies the proposed utilization of simple phenotypic markers for optimizing treatments in individual patients.