Patient/caregiver-reported recombinant factor VIIa (rFVIIa) dosing: home treatment of acute bleeds in the Dosing Observational Study in Hemophilia (DOSE)

Patients with congenital haemophilia with inhibitors experience acute bleeds managed with bypassing agents, such as recombinant FVIIa (rFVIIa). Home-based treatment and dosing patterns in the US remain poorly described. This study aimed to assess the prescribed and actual rFVIIa dosing in frequently bleeding inhibitor patients (≥4 bleeds in 3 months) prescribed first-line therapy with rFVIIa. Patients or caregivers recorded daily diaries, including the details of all bypassing agent infusions for 3-6 months. Median (range) initial rFVIIa dose prescribed for joint, muscle and other bleeds was 167.5 (61.0-289.0) mcg kg(-1). Additional rFVIIa doses prescribed were 90 (61-270) mcg kg(-1) at an interval of 2.5-3 (1-24) h. The actual initial rFVIIa dose reported by patients/caregivers for 158 bleeds was 212 (59-400) mcg kg(-1), with total dose per episode of 695 (74-21257) mcg kg(-1). Patient/caregiver-reported average dose per bleed was 146 (40-400) mcg kg(-1) across 5 (1-106) infusions. The initial rFVIIa dose was higher for haemarthrosis (223 [59-400] mcg kg(-1)) than muscle bleeds (148 [74-300] mcg kg(-1); P = 0.07). Initial and mean dose per day changed as treatment progressed. The DOSE study indicates that frequently bleeding inhibitor patients are prescribed and use higher rFVIIa dosing for all bleed types than recommended in the package insert (90 mcg kg(-1)). The rFVIIa dosing was highly variable within and across bleed types, with higher initial doses used for joint bleeds than muscle and other bleed types, particularly in the first days of treatment. This suggests that patients/caregivers have adopted home treatment strategies based on physician discretion and individual responses and experience.