Willebrand in the Netherlands: WiN Study. Background and Study Design

The clinical presentation of patients with Willebrand Disease (VWD) is highly variable, and not always predictable upon laboratory measurements. The mechanism of this clinical variability is unknown. Also the impact of VWD on the quality of life is highly variable between patients.

This ongoing study aims to register and investigate all patients in the Netherlands with moderate and severe von Willebrand Disease to assess clinical presentation, treatment and related complications of treatment. One of the aims is to assess which factors influence the bleeding phenotype. Another goal is to investigate the influence of von Willebrand Disease on quality of life.

We have identified 1071 eligible patients. All patients are known at 12 hemophilia treatment centers. Inclusion criteria are moderate or severe VWD defined as; VWF antigen or activity ≤ 30% and/or FVIII:C ≤ 40%. The patients will be sent a questionnaire and a blood sample will be obtained for plasma and DNA.

The characteristics of the patients are the following: median age is 34 years (range 0–86) in males and 42 years (range 1–92) in females. 192 children are included (<18 years). Sixty-one percent is female. In this cohort 59% has type 1, 30% has type 2, 4,5% has type 3, 0.5% is compound heterozygote and 6% is non-specified. Among type 2 we identified 50% 2A, 26% 2B, 10% 2M, 6% 2N, and 8% non-specified. In this cohort 45% has blood group 0, 29% non-0 and in 26% this is unknown. The VWF:Ag, VWF:Act (CB or RCo) and FVIII:C levels are mentioned in table 1.

Conclusion: The WiN study has identified 1071 moderate to severe VWD patients in the Netherlands who will form the basis for further research that will result in more insight into the clinical features and quality of life in VWD.

Table 1: