Prevalence of Synovitis in Persons with Haemophilia A – an interim report

Introduction Joint health is becoming increasingly important for patients with haemophilia. Synovitis is considered a precursor to haemophilic arthropathy, which has a clinical and subclinical impact on joint health and requires treatment. From an epidemiological perspective, however, the prevalence of synovitis and its relationship to other conditions remain unclear. The aim of this study is therefore to conduct a statistically representative prevalence analysis and to describe the occurrence and quality of synovitis in detail. Method In a multicenter prospective cross-sectional design, 300 persons with haemophilia A (PwHA) aged 18 years and older will be enrolled at 20 centers in Germany and Austria. The project began in March 2024 and is scheduled for 3 years. This analysis is considered an interim report. The primary endpoint is a sonographic joint examination based on the defined Haemophilia Early Arthropathy Detection with Ultrasound (HEAD-US) protocol. In addition, the Haemophilia Joint Health Score (HJHS) will be performed for the clinical joint examination. Supplementary secondary endpoints include questionnaires such as the Haemophilia Activities List (HAL), PROMIS-29 questionnaire, and the haemophilia-specific treatment regimen. Results By October 2025, 141 patients had been included in the study and are the source of the following results. The anthropometric description of the cohort can be found in [ Fig. 1 ]. Fig. 1 Description of anthropometric data. Data presented as mean±standard deviation (minimum-maximum). HJHS=Haemophilia Joint Health Score; ABR=Annual bleeding rate; EHL=Extended Half-Life Factor; SHL=Standard Half-Life Factor; NFT=Non-Factor-Therapy. The interim prevalence rate of synovitis (HEAD-US total activity score≥1) is 74%. At joint level, this affects the ankle joint in 40% of cases, the elbow in 34% and the knee in 19%. An examination of the relationships between the presence and severity of synovitis shows a moderate correlation with impairment due to pain. In addition, there are moderate negative correlations between synovitis and physical function as well as limitations in everyday activities ([ Fig. 2 ]). Fig. 2 Correlogram of the analyses between HEAD-US total Activity, HEAD-US total Damage, PROMIS-29 Pain Interference, PROMIS-29 Physical Function, and HAL sum score (n=141). Results are presented as r-values. The more blue (positive correlation) or the more red (negative correlation) the colour of the boxes the stronger the correlation is (see bar right to the correlogram). HEAD-US=Haemophilia Early Arthropathy Detection with Ultrasound. Conclusion It shows a noteworthy preliminary prevalence rate of synovitis in PwHA of 74%. Furthermore, the presence of synovitis appears to influence pain interference and physical function in PwHA, which can potentially affect their quality of life. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany