ATHN 9: A Natural History Cohort Study of the Safety, Effectiveness, and Practice of Treatment for People with Severe Von Willebrand Disease (VWD)

Von Willebrand disease (VWD) is the most common inherited bleeding disorder in humans, caused by missing or defective von Willebrand factor (VWF), a clotting protein. The primary objective of ATHN 9: Severe VWD Natural History Study, a longitudinal and observational study, is to assess the safety and efficacy of various VWF regimens for different indications in patients with clinically severe VWD.

ATHN 9: Severe VWD Natural History Study draws from adult and pediatric patients with clinically severe VWD. Safety will be measured by the number of reported events as defined by the European Haemophilia Safety Surveillance (EUHASS) program, which include: hypersensitivity/allergic reactions, thrombotic events, VWF inhibitor development, treatment-emergent side effects of therapy, transfusion-transmitted infections, malignancy, cardiovascular events, neurological events, and death.

Secondary objectives include:

• Enriching and analyzing the data from currently enrolled patients with clinically severe congenital VWD in the ATHNdataset via the collection of laboratory data from VWF-specific testing
• Establishing a platform of sub-studies for patients with congenital severe VWD who are treated with VWF products on demand or have started on or switched to a particular VWF-containing product for prophylaxis
• Evaluating the use of factor replacement as prophylaxis in a cohort of participants over 6-month time periods
• Describing the bleeding pattern, changes in overall bleeding, and annualized bleeding rate (ABR) as measured by individual bleeding components, calculated per ISTH Bleed Assessment Tool and, if applicable, the Pictorial Bleeding Assessment Chart
• Understanding the real-world effectiveness of VWD treatment as measured by health care utilization and health-related quality of life questionnaires.

Approximately 130 participants will be enrolled in ATHN 9: Severe VWD Natural History Study. Participants will be followed longitudinally for 2 years from the time of enrollment for a total planned study duration of 3 years. Each participant will be seen during a clinic visit or contacted at least once every 6 months.