[1] Royal Free London NHS Fdn Trust, Katharine Dormandy Haemophilia Ctr, London NW3 2QG, England
[2] Royal Free London NHS Fdn Trust, Thrombosis Unit, London NW3 2QG, England
[3] Univ Brighton, Ctr Hlth Res, Eastbourne, England
[4] Univ Brighton, Sch Hlth Profess, Eastbourne, England
[5] McMaster Univ, Dept Clin Epidemiol & Biostat, Hamilton, ON, Canada
[6] McMaster Univ, Hamilton Niagara Hemophilia Program, Hamilton, ON, Canada
[7] McMaster Univ, Dept Med, Hamilton, ON, Canada