A survey of factor prophylaxis in boys with haemophilia followed in North American haemophilia treatment centres

A survey was conducted in 2002 to determine the pattern of factor prophylaxis use in boys ≤18 years of age with haemophilia followed in North American treatment centres. Responses were obtained from 4553 cases (74% haemophilia A, 26% haemophilia B). The frequency of prophylaxis, defined as factor infusion greater than or equal to once per week for ≥45 weeks per year, was significantly higher for haemophilia A vs. haemophilia B cases (51% vs. 32%, P<0.0001), and for boys with severe haemophilia A living in Canada vs. the USA (77% vs. 47%, P<0.0001). Use of full-dose prophylaxis, defined as the infusion of 25-40 IU kg^-1 of factor VIII on alternate days (minimum three times per week) or 25-40 IU kg^-1 of factor IX twice weekly, was similar for boys ≤5 years of age in both Canada and the USA (30% and 33% haemophilia A and 35% and 13% haemophilia B). Reasons for initiating prophylaxis included a history of joint bleeding (88%) and age ≤2 years (23%). For prophylaxis triggered by joint bleeding, 38% of haemophilia treatment centres indicated that they would initiate prophylaxis after the first joint bleed and 66% after a history of target joint bleeding, defined most frequently as 2-4 bleeds over a 3-6 consecutive month period. A central venous line was used to ensure easy venous access for full-dose prophylaxis therapy in 80% of boys ≤5 years of age. These data offer a basis for projecting long-term factor concentrate needs for persons with haemophilia living in North America.