The investigators propose to study longitudinal joint and bone density changes in patients with severe Hemophilia A. Per current standard of care, most patients are on prophylactic FVIII replacement therapy intravenously several times weekly with a goal of keeping the trough >1% FVIII. Recent phase 3 data suggest superior bleed protection with emicizumab prophylaxis every 1-2 weeks. It is the purpose of this study to longitudinally assess joint health and bone density over 3 years and to compare the effect of routine factor VIII prophylaxis with emicizumab prophylaxis.
Summary: This retrospective/prospective, non-randomized controlled study, whereby patients will be included in 1 of 2 groups depending on their current treatments as outlined below. Patients will be assigned to a specific group by the clinician/PI based on their current regimen with the intent to stay on this regimen for the next 3 years.
Duration of Study and Subject Participation: Study subject enrollment is anticipated to occur over about 12 months and study duration per subject will be 3 years. Thus a total study duration of 4 years is anticipated.
Intervention: By using musculoskeletal ultrasound, the investigators will measure joint health among participants and assess joint health changes over 3 years compared between group A (factor prophylaxis) vs. group B (emicizumab prophylaxis) as assessed by MSKUS at baseline and after 3 years. Other outcomes such as bone density, comparative assessment of joint and overall health status, and exploration of potential biomarkers for joint and bone health will also be assessed.