Clinical Research Directory

Inclusion Criteria: * Boys with moderate/severe hemophilia A, with or without FVIII inhibitors, age 7-18 years, * Group A: who have previously received prophylaxis with SHL or EHL CFCs at least once a week for the previous year who plan on switching or who have switched to emicizumab. * Group B: who are currently receiving prophylaxis at least once a week for the previous year with any form of treatment other than emicizumab who are not switching treatment regimens. * Group C: who have not been on long-term prophylaxis for the year prior to study commencement who begin prophylactic treatment with emicizumab (i.e., previously untreated patients or patients receiving treatment on demand). * Group D: boys with moderate/severe hemophilia A who have neutralizing alloantibodies to FVIII (FVIII inhibitors), defined as a level of ≥0.6 Bethesda Units (BU) using the Nijmegen modification of the Bethesda assay on two separate occasions within a 1-4 week period1, who are receiving a by-passing hemostatic agent such as a non-activated or activated plasma-derived, virus-inactivated prothrombin complex clotting factor concentrate (e.g., FEIBA), recombinant FVIIa (Niastase), or emicizumab. FVIII Inhibitors of \<5 BU are considered low titer and those ≥5 BU are considered high titer. * Parents/caregivers of boys with moderate/severe hemophilia A with or without FVIII inhibitors between the ages of 0-18 years. * Moderate or severe hemophilia A, defined as FVIII activity level ≤5%. * Ability to understand the purpose and risks of the study and provide signed and dated informed consent and authorization to use protected health information (PHI) in accordance with national and local subject privacy regulations. Exclusion Criteria: Candidates will be excluded from study entry if any of the following criteria exist at the time of screening, or at the time point specified in the individual criterion listed: * Boys with mild hemophilia A, defined as a FVIII activity between 5-40%. * Presence of significant comorbid diseases (e.g., HIV) as per the judgement of the clinical team. * Inability to read, write, and/or understand English or French. * Unable or unwilling to provide informed consent.