1. Department of Vascular Surgery, Catharina Hospital, PO Box 1350, 5602 ZA, Eindhoven
2. Department of Epidemiology, CAPHRI Research School, Maastricht University, PO Box 616, 6200 MD, Maastricht
3. Department of Clinical Epidemiology, Erasmus MC, PO Box 2040, 3000 CA, Rotterdam, The Netherlands