1. Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht/Utrecht University, Str. 6.131, PO Box 85500, 3508 GA Utrecht, the Netherlands
2. Thrombosis Service, Isala Hospital Zwolle, Postbus 10400, 8000 GK Zwolle, the Netherlands
3. Department of Cardiology, Isala Hospital Zwolle, Postbus 10400, 8000 GK Zwolle, the Netherlands
4. Department of Internal Medicine, Isala Hospital Zwolle, Postbus 10400, 8000 GK Zwolle, the Netherlands
5. Department of Internal Medicine, University Medical Center Groningen/University of Groningen, Postbus 30.001, 9700 RB Groningen, the Netherlands