Note: Funding Information: We highly appreciate the participation of all subjects in our study. The use of data from the PedNet Registry belonging to the PedNet Haemophilia Research Foundation and all help from its personnel is greatly acknowledged. A list of contributors is given in the Appendix. The study was funded by the Arosenius Foundation Research Grant (founded by the Swedish Haemophilia Patient Association, N.G. Andersson), by the Swedish Research Council (grant number: 2015‐02957, R. Ljung) and “Bayer‐Award” (R. Ljung). Funding Information: We highly appreciate the participation of all subjects in our study. The use of data from the PedNet Registry belonging to the PedNet Haemophilia Research Foundation and all help from its personnel is greatly acknowledged. A list of contributors is given in the Appendix. The study was funded by the Arosenius Foundation Research Grant (founded by the Swedish Haemophilia Patient Association, N.G. Andersson), by the Swedish Research Council (grant number: 2015-02957, R. Ljung) and ?Bayer-Award? (R. Ljung).