OBJECTIVES: Patients with congenital hemophilia with inhibitors (CHwI) experience acute bleeds that are managed with bypassing agents such as rFVIIa. Home treatment and dosing patterns in the US remain unknown. This study aimed to assess differences between prescribed/actual rFVIIa dosing in frequently-bleeding CHwI patients (≥4 bleeds/3 months) prescribed first-line therapy with rFVIIa. METHODS: Patients or caregivers recorded daily diaries including the details of all bypassing agent infusions on bleed/treatment days for 3-6 months. RESULTS: Median (range) initial rFVIIa dose prescribed by physicians for joint, muscle and other bleeds was 167.5 mcg/kg (61.0-289.0). Approximately 50% of initial rFVIIa doses prescribed were ≥160 mcg/kg and 35% were ≥240 mcg/kg. Median prescribed additional rFVIIa dose for all bleeds was 90 mcg/kg (61.0-270.0) at an interval of 2.5-3 (1-24) hours. Median (range) actual initial rFVIIa dose reported by patients for 158 bleeds was 211.6 mcg/kg (59.3-400.0), with total dose per episode of 694.9 mcg/kg (74.1-21,257.4). Patient/caregiver reported average dose per bleed was 146.1 mcg/kg (39.5-400) across 5 (1.0-106.0) infusions. The initial rFVIIa dose was higher for joint bleeds (223.0 mcg/kg [59.3-400.0]), compared with muscle (148.1 mcg/kg [74.1-300.0]; P=0.07) and other bleeds (166.7 mcg/kg [64.0-400.0]; P=0.02). Initial rFVIIa dose was ≥160 mcg/kg in 65% of all bleeds and 73% of joint bleeds. The second dose for all bleeds was 131.5 mcg/kg (29.6-379.7) with 43% being ≥160 mcg/kg and 27% ≥240 mcg/kg. CONCLUSIONS: Prescription data from the DOSE study demonstrate higher initial dosing for all bleed types than the package insert recommended dose of 90mcg/kg. Additional prescribed dosing (where required) more closely conformed to package insert recommendations. Patient/caregiver reported actual dosing was generally higher than that prescribed, both for initial dosing (particularly for joint bleeds) and for additional dosing. These data suggest that patients/caregivers may have adopted home treatment strategies based upon individual responses and experience.