The relevance of the study will be in establishing whether Health Related Quality of Life (HRQoL) measures obtained repeatedly during hemophilia care are sensitive to significant changes in health or personal circumstances related to the transition from youth to adulthood. This may support the future use of HRQoL measures as part of routine care in order to identify important changes that are not detectible by other clinical means.

Inclusion Criteria:

• Moderate or severe Hemophilia A (factor level ≤5%)
• Receiving Helixate FS as on-demand treatment or prophylaxis therapy at time of informed consent
• Patient age 14 to 29 years at the time of recruitment
• Complete informed consent process and documentation; (Patients under age 18 must assent in addition to consent of legal guardian)
• Willing/able to follow study protocol, including keeping a bleeding and treatment diary
• Able to communicate clearly in either English or French - both written and verbal communication is essential.

Exclusion Criteria:

• Known inhibitor at time of recruitment (> 0,5 Bethesda units) or immune tolerance therapy at time of recruitment
• HIV positive
• Symptomatic Hepatitis B or C infection or active treatment for hepatitis B or C
• Inability to comply with study protocol
• Hypersensitivity to Helixate FS or to any ingredients in the formulation or component of the container
• Hypersensitivity to mouse or hamster protein
• Unsuitable to participate in study for any other reason as assessed by investigator

The study is focused on youth (14.0 to 18.0 years of age) and young adults (18.01 to 29.99 years of age), living in Canada, who have moderate and severe Hemophilia A, and who are using Helixate FS either on-demand or as prophylaxis treatment.