1. Department of Clinical Epidemiology Leiden University Medical Center Leiden the Netherlands
2. Department of Clinical Pharmacy and Toxicology Leiden University Medical Center Leiden the Netherlands
3. Thrombosis Service of Amsterdam (Atalmedial) Amsterdam the Netherlands
4. Thrombosis Service of the Hague (LabWest) The Hague the Netherlands
5. Division of Thrombosis and Hemostasis Leiden University Medical Center Leiden the Netherlands
6. Kennisinstituut van de Federatie Medisch Specialisten Utrecht the Netherlands