1. Department of Clinical Epidemiology Leiden University Medical Center Leiden the Netherlands
2. Angelo Bianchi Bonomi Hemophilia and Thrombosis Center Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico and Luigi Villa Foundation Milan Italy
3. Department of Pediatric Hematology Emma Children's Hospital Academic Medical Center Amsterdam the Netherlands
4. Center for Clinical Transfusion Research Sanquin Research Leiden the Netherlands