Response: Diagnosing VWD type 1: when is it useful and when illogical?

Dr Lipton raises an important question about the best strategy for managing patients with moderately decreased levels of von Willebrand factor (VWF). One need not medicalize every small predisposition to a future adverse event by giving it an eponymous diagnosis. I like the comparison to fair skin as a risk factor for skin cancer, and I've used it myself in discussing von Willebrand disease (VWD) type 1. We also take a similar approach to high blood pressure, managing it empirically as a modest risk factor for cardiovascular events. With respect to low VWF levels, the community is still figuring out the best approach. The problem was discussed in some detail in the revised guidelines for diagnosing VWD that were published recently on behalf of the International Society on Thrombosis and Haemostasis.¹  This paper prompted a similar exchange of letters about how to define VWD type 1 and which patients should be considered simply to have “low VWF” instead.^2,3  On one hand, VWF levels lower than 20 IU/dL usually are associated with VWF mutations, significant bleeding symptoms, and a high likelihood of transmitting the condition to progeny. A diagnosis of VWD type 1 seems appropriate in such cases. On the other hand, VWF levels closer to 50 IU/dL have none of these properties, and a label of “disease” is illogical. For the troublesome intermediate levels, we need more information, especially about the risk of bleeding and the benefits of treatment. Is there a threshold, a natural boundary that separates patients into useful categories? If so, then we could treat those below as VWD type 1 and those above as possessors of low VWF, a risk factor for mild bleeding. The ongoing studies of VWD in Europe and in Canada are starting to provide this information and should help to define a more satisfactory approach to diagnosing, treating, and advising our patients with modest, quantitative decreases in VWF.