Validation Study of a cOmputer Pharmacokinetic Tool to assIst in the Follow up Care of haeMophilia A Patients

Inclusion Criteria: * Patient with severe haemophilia A defined as residual factor VIII activity \< 1% * or Patient with moderate haemophilia A (residual factor VIII activity \>1% and \<5%) with severe clinical profile * Patient treated in prevention with the same plasma or recombinant factor VIII for at least 6 months * Patient whose inclusion visit is performed during a routine visit including a measurement of plasma residual factor VIII :c level * In the medical file (retrospective data) the pharmacokinetic parameters are available and have been obtained from a PK analysis of factor VIII level performed with the same anti haemophilic factor than the one used on the inclusion day Exclusion Criteria: * Patients with haemophilia B