for males ages 16 years and up (full criteria)
at San Diego, California and other locations
study started
completion around
Principal Investigator
by Annette Von Drygalski, MD, PharmD
Headshot of Annette Von Drygalski
Annette Von Drygalski



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.


Hemophilia A, Joint Health, Bone Density, Emicizumab, factor VIII prophylaxis, assessment of joint health and bone density


You can join if…

Open to males ages 16 years and up

  • Male gender
  • Severe hemophilia A (factor VIII < 1%)
  • Age ≥ 16 year
  • Either on prophylaxis with factor VIII or emicizumab with the intention to stay on the current regimen for the next 3 years
  • Willing and able to give written informed consent/assent
  • Willing to undergo MSKUS, DEXA scan +/- collection of blood sampling for repository biomarkers
  • Willing to come in for baseline and 3 yearly visits
  • Willing to answer phone survey for bleeding and safety every 3 months

You CAN'T join if...

  • Current FVIII inhibitor of > 0.6 BU
  • Unable to take FVIII replacement
  • Other known bleeding disorder
  • Other rheumatologic disorder affecting joints
  • Other known neuromotor defect (making physical exam difficult)


  • Hemophilia and Thrombosis Treatment Center, University of California, San Diego accepting new patients
    San Diego California 92092 United States
  • Orthopedic Hemophilia Treatment Center not yet accepting patients
    Los Angeles California 90007 United States
  • Washington Center for Bleeding Disorders at Washington Institute for Coagulation accepting new patients
    Seattle Washington 98101 United States
  • The University of Texas Health Science Center at San Antonio accepting new patients
    San Antonio Texas 78229 United States

Lead Scientist at UCSD

  • Annette Von Drygalski, MD, PharmD
    Dr. von Drygalski is the Director of the Hemophilia and Thrombosis Treatment Center at UCSD ( and her research interests involve basic, translational and clinical science in the field of hemostasis and thrombosis, specifically hemophilia. Dr. von Drygalski collaborates with Laurent O. Mosnier and John H.


accepting new patients
Start Date
Completion Date
Washington Institute for Coagulation
Study Type
Expecting 40 study participants
Last Updated