Joint damage common in Chilean children with severe hemophilia
Study: They experience these issues despite receiving preventive treatment
Half of the children in Chile with severe hemophilia A and B exhibit joint damage despite receiving preventive treatment with clotting factors, a study reports.
Damage to the cartilage is the main sign of joint impairment in children older than 8 years, while synovitis, or inflammation of the synovial membrane that lubricates and nourishes the joints, is more commonly observed in younger children.
Adherence to preventive therapy and residence in a metropolitan region were identified as key protective factors against joint damage.
“These findings emphasise the necessity of pairing prophylaxis with ongoing joint health monitoring and support from specialised haemophilia teams,” researchers wrote.
The study, “Joint health in Chilean children with haemophilia on primary prophylaxis,” was published in the journal Thrombosis Research.
Bleeding into joints a hallmark sign of severe hemophilia
Hemophilia is a condition characterized by inadequate blood clotting caused by either the absence or dysfunction of certain clotting proteins. In the case of hemophilia A, the specific protein that is deficient or defective is factor VIII (FVIII), while in hemophilia B, it is factor IX (FIX).
A hallmark sign of severe hemophilia is bleeding into the joints. Joint bleeds and subsequent inflammation can cause damage and lead to hemophilic arthropathy, or long-term, irreversible damage to the joints. Preventing joint damage, especially in children, is crucial for ensuring health in adulthood.
Preventive treatment, or prophylaxis, that relies on the regular infusion of FVIII or FIX concentrates is a standard treatment in severe cases. These treatments can be categorized into standard half-life and extended half-life products, based on the duration that the administered clotting factor remains effective in the bloodstream. Unlike standard half-life therapies, extended half-life therapies involve molecular alterations to enhance the longevity of the clotting factors’ activity within the body.
Chile implemented a comprehensive health program for hemophilia treatment in 2006, but the data regarding the efficacy of prophylaxis is limited. Adherence to treatment is influenced by various factors, and monitoring joint health is essential for assessing therapy efficacy.
While MRI is the gold standard method for monitoring joints, the need for specialized personnel and high costs make its routine use difficult, especially in children. Ultrasound, specifically a method created especially for hemophilia patients — called Haemophilia Early Arthropathy Detection with Ultrasound (HEAD-US) — represents a cost-effective method to detect early joint changes and guide treatment adjustments.
Treatment adherence found to be protective against joint damage
In this study, researchers in Chile used HEAD-US to evaluate the effectiveness of primary prophylaxis on joint health in Chilean children with hemophilia. Additionally, they aimed to identify protective and risk factors that could inform health policy in similar settings.
Primary prophylaxis was defined as the continuous infusion of clotting factors from the first joint bleed or before the age of 2.
They analyzed data collected between September 2023 to May 2024 from children with hemophilia, with a median age of 8 years, across 23 public centers in Chile, which covered 85 % of the total population in Chile.
Among the 86 children included in the analysis, 79% had severe hemophilia A and 21% severe hemophilia B. Half of the children receiving standard half-life prophylaxis had damage in at least one joint, and 22 % had damage in more than one joint. Joints in the ankles were the most commonly affected (59.2%), followed by the elbow (21.1%) and knee (19.7%).
Both treatment adherence and living in a metropolitan region were found to be protective against joint damage. Specifically, children who did not adhere to prophylaxis were 7.2 times more likely to experience joint damage, while those living outside a metropolitan area faced a 2.7 times greater risk.
Ankle joint showed significant differences in damage according to age
Children receiving regular HEAD-US assessments at two specialized centers in the metropolitan region exhibited significantly less joint damage compared to children in other centers (7 vs. 36 cases).
Furthermore, those who consistently adhered to morning prophylaxis had lower HEAD-US scores compared to non-adherent children. A lower HEAD-US score means fewer or less severe changes in the joint structure, indicating a positive outcome related to their adherence to prophylactic treatment.
Children older than 8 years showed lower adherence rates to morning prophylaxis compared to younger ones.
The ankle joint showed significant differences in joint damage according to age, with children older than 8 years exhibiting a higher incidence of damage. Total HEAD-US scores, which assess joint health across the elbow, knee, and ankle, were significantly higher in older children compared to younger ones. No notable differences were observed in the knee and elbow joints between the two age groups.
Children older than 8 had higher HEAD-US scores for the ankle joint and also showed significant increases in scores related to cartilage, synovitis, and the subchondral bone (the layer of bone that lies just under joint cartilage) compared with younger children.
“Given that primary prophylaxis is widely acknowledged as the gold standard for preventing joint damage, it should be complemented by ongoing joint health monitoring, strategic interventions to improve adherence, and initiatives to ensure equitable access to specialised multidisciplinary medical teams, all aimed at preventing long-term disability in children with haemophilia,” the researchers concluded.
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