Abstract

Introduction Primary prophylaxis is the gold standard in severe haemophilia A and B. Proper monitoring and follow-up of this treatment are essential for achieving good outcomes. Haemophilia Early Arthropathy Ultrasound (HEAD-US) helps assess joint status and detect initial damage. Our study aimed to evaluate the effectiveness of primary prophylaxis on joint health through HEAD-US in the paediatric population in Chile. Method We selected all patients under 15 years old in the country with severe haemophilia A or B who had received primary prophylaxis with plasma-derived FVIII/FIX products. Variables included in the analysis were joint health, treatment adherence (Veritas-Pro), morning prophylaxis treatment, home and hospital administration of treatment, and residence in the metropolitan region. Results Eighty-six children from 23 public centres were assessed (covers 85 % of the total population in Chile). Half of the children receiving standard half-life FVIII/IX prophylaxis still present joint damage, with the ankle the most affected joint. Among protective factors for joint health, adherence and living in the metropolitan region showed a significant odds ratio (p < 0.05). Conclusion Joint damage was present in 50% of the children, with the ankle being the most affected. Cartilage damage is a key marker in children over eight, while synovitis is predominant in younger ones. Adherence to prophylaxis and living in the metropolitan region are protective factors. These results highlight the importance of monitoring joint health and using HEAD-US for early screening in children on primary prophylaxis.