Among patients with severe hemophilia A or B (SHA and SHB, respectively), primary prophylaxis appears to be initiated at a younger age in recent years, according to research published in Haemophilia.

Primary prophylaxis, which involves infusion of clotting factor concentrates, is used to reduce the severity of SHA and SHB. There is, however, debate about when it is best to initiate therapy. Researchers have made inconsistent recommendations, for example, about whether to start primary prophylaxis at first joint bleed before a patient is 3 years of age, or to initiate treatment before 3 years regardless of the presence of joint bleeds.

It was also previously unknown the degree to which publications in the last several years have influenced clinicians about when to initiate therapy. For this study, researchers evaluated real-world data to determine any changes in prophylactic treatment practices among previously untreated patients with SHA or SHB.

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Overall, data from 1260 and 182 patients with SHA and SHB, respectively, were included. These data were divided into 2 cohorts: cohort 1, where patients were born between 2000 and 2009 (662 and 88 patients with SHA and SHB, respectively), and cohort 2, where patients were born between 2010 and 2019 (598 and 94 patients with SHA and SHB, respectively).

Among patients with SHA, patients in cohort 1 initiated prophylaxis at a median age of 17.3 months, compared with 13.1 months in cohort 2 (P <.05). Between cohorts 1 and 2, once-a-week prophylaxis at initiation increased from 49% to 68% among patients with SHA and from 38% to 70% among patients with SHB.

Furthermore, factor VIII doses appeared to drop from a median of 43.5 to 30.9 IU/kg between the birth cohorts, though factor IX dosage did not change.

The data also suggested that, after 2010, 60% of patients with severe hemophilia initiated prophylaxis prior to any joint bleed.

“Once weekly dosing at start of prophylaxis increased to 70% for both patients with SHA and SHB, while the dose used for those with SHA was decreased significantly,” the authors wrote in their report.


Ljung R, de Kovel M, van den Berg HM; PedNet study group. Primary prophylaxis in children with severe haemophilia A and B-Implementation over the last 20 years as illustrated in real-world data in the PedNet cohorts. Haemophilia. Published online December 26, 2022. doi:10.1111/hae.14729