1. From the Departments of Internal and Vascular Medicine (B.-J.H.v.d.B., N.V.v.d.H., J.C.M.M., M.L., G.A.v.M.), Academic Medical Centre, Amsterdam, The Netherlands; and the Laboratory for Thrombosis and Hemostasis (E.G., P.J.L.), Department of Clinical Chemistry and Haematology, University Medical Centre Utrecht, Utrecht, The Netherlands.