Ultrasound Assessment of Joint Health in Patients With Mild Hemophilia (Factor Levels 5-40%)

Hemophilia is an inherited bleeding disorder caused by a deficiency of factor VIII (hemophilia A) or factor IX (hemophilia B), predominantly affecting males, although female carriers can also be symptomatic, often in a milder form. The incidence of hemophilia is similar worldwide, with hemophilia A occurring in approximately 1 in 5,000 births and hemophilia B in 1 in 25,000 births. In France, over 8,000 patients with hemophilia A and 2,000 patients with hemophilia B have been reported, with approximately one-third presenting with severe disease, over 10% with moderate disease, and 60% with mild disease.

Severe hemophilia is associated with frequent and potentially serious bleeding, including joint bleeding, which can lead to progressive and irreversible hemophilic arthropathy. Optimized hemostatic treatments and early detection strategies, such as joint ultrasound, have markedly improved outcomes in severe cases. However, little is known about joint health in patients with mild hemophilia. Although bleeds are less frequent and rarely spontaneous in these patients, they remain at risk of developing arthropathy, including from asymptomatic micro-bleeds.

This study aims to provide objective data on joint health in mild hemophilia patients in France and to explore potential correlations between coagulation factor levels (FVIII or FIX) and other indicators of joint involvement. The results are expected to improve understanding of joint disease in this population and may help guide future preventive and therapeutic strategies.

• Joint Ultrasound (HEAD-US) (Other): Ultrasound evaluation of six joints (both ankles, knees, and elbows) by a designated expert using the HEAD-US scoring system to assess joint health and detect early arthropathy.
• Blood Sample for Coagulation Factor Measurement (Other): Blood sample collected according to local laboratory procedures to measure coagulation factor activity (FVIII for hemophilia A, FIX for hemophilia B).

Primary outcomes

• Haemophilia Early Arthropathy Detection with UltraSound (HEAD-US) score [At inclusion visit]: Ultrasound evaluation of six joints (elbows, knees, and ankles) using the HEAD-US scoring system (score range 0-48, where lower scores indicate better joint status) to assess joint health and detect early arthropathy.
• FVIII or FIX Activity [At inclusion visit]: Blood sample measurement of FVIII or FIX activity according to local laboratory procedures (score range 5-40).

Secondary outcomes

• Haemophilia Functional Ability Scoring Tool (Hemo-FAST) [At inclusion visit]: Clinical assessment of joint function using the HemoFAST score performed by the physician or designated representative (score range 0-100, where 0 indicates best joint function and higher scores indicate worse joint function).
• Haemophilia Activities List (HAL) [At inclusion visit]: Patient-reported questionnaire evaluating functional ability using the validated French translation (score range 0-100, with higher scores indicating better function).
• Haemophilia-Associated Quality of Life Questionnaire for Adults (Haem-A-QoL). [At inclusion visit]: Patient-reported questionnaire evaluating quality of life using the validated French translation (score range 0-100, with higher scores indicating poorer quality of life).
• EuroQol 5-Dimension 3-Level Questionnaire (EQ-5D-3L) [At inclusion visit]: Patient-reported questionnaire evaluating health status using the validated French version of the EQ-5D-3L (descriptive system).
• International Physical Activity Questionnaire (IPAQ) [At inclusion visit]: Patient-reported questionnaire assessing physical activity levels using the IPAQ. Scores are derived according to standard IPAQ scoring procedures.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Adult (≥18 years old) with congenital mild hemophilia, defined as historical coagulation factor level >5% and <40% (FVIII or FIX).
* Affiliated with a social security system.
* Provided written informed consent to participate in the study.

Exclusion Criteria:

* Patient on prophylactic treatment, defined as at least one of the following:

  o. ≥5 factor concentrate injections per month for a period of more than 6 months o. Treatment with emicizumab o. Last factor concentrate injection within the past 28 days
* Patient with acquired hemophilia.
* Patient with uncontrolled chronic rheumatologic disease, such as rheumatoid arthritis, inflammatory spondyloarthropathies, or microcrystalline arthritis.
* Known pregnancy or breastfeeding.
* Patient deprived of liberty or under legal guardianship or conservatorship.

• Laurent FRENZEL, Principal investigator, Hôpital Necker Enfants Malades AP-HP