[1] Univ London Imperial Coll Sci Technol & Med, Ctr Haematol, Fac Med, London W12 0NN, England
[2] Leiden Univ, Dept Clin Epidemiol, Med Ctr, Leiden, Netherlands
[3] Univ Med Ctr Utrecht, Julius Ctr Hlth Sci & Primary Care, Utrecht, Netherlands
[4] Univ Med Ctr Utrecht, Dept Neurol & Neurosurg, Utrecht Stroke Ctr, Utrecht, Netherlands
[5] Leiden Univ, Dept Thrombosis & Hemostasis, Med Ctr, Leiden, Netherlands