Individualised prophylaxis based on personalised target trough FVIII level optimised clinical outcomes in paediatric patients with severe haemophilia A.

Abstract

As standard care of severe haemophilia A (SHA), prophylaxis should be individualised. This study aimed to investigate the effectiveness of this new-proposed individualised prophylaxis protocol. Boys with SHA were enrolled and followed a PK-guided, trough-level escalating protocol of prophylaxis after a six-month observational period. In the next 2 years, clinical assessments including joint bleeds, ultrasound (US) scores and Haemophilia Joint Health Score (HJHS) in both sides of ankles, knees and elbows were conducted every 6 months as a scoring system, which determined whether the trough level's escalation. Adjustment of dosing regimen was based on WAPPS-Hemo. Fifty-eight SHA boys were finally analysed. Their age and bodyweight were 5.3(2.8,6.9) years and 21.5(16,25) kg. During the study, 47 escalations were conducted. At study exit, the patient number and proportion of different trough level groups were:<1IU/dl, 17.2% (10/58); 1-3IU/dl, 53.5% (31/58); 3-5IU/dl, 15.5% (9/58);>5IU/dl, 13.8% (8/58). Significantly reduced annualised bleeding rate [4(0,8) to 0(0,2), p<.0001] and annualised joint bleeding rate [2(0,4) to 0(0,.25), p<.0001] was observed at study exit as well as the continuous trend of increased zero bleeding proportion (ZBP) (27.6%-69.0%) and zero joint bleeding proportion (46.5%-81.3%). Besides, 85% (6/7) of the target joints vanished. Statistical improvements of US scores (p=.04) and HJHS (p=.02) were also reported at study exit. Our results showed the effectiveness of our protocol based on individualised target trough level and emphasise the importance of personalised prophylaxis.