Subject disposition. After screening, all subjects on a prophylactic regimen prior to study entry were to enter into arm 1; subjects on an episodic regimen prior to study entry were to enter into arm 1 or be randomized into either arm 2 or 3, with randomization stratified based on individual annualized bleeding episodes in the prior 12 months. Of the 30 subjects enrolled in the arm 1 sequential pharmacokinetics (PK) group, 28 had evaluable PK profiles for both rFVIII and rFVIIIFc; repeated PK analysis for rFVIIIFc was performed at weeks 12 to 24. Of the 164 subjects in the 3 arms combined, 4 subjects (2.4%) experienced AEs that led to discontinuation of rFVIIIFc treatment and/or withdrawal from the study: rash in 1 subject (assessed as related to rFVIIIFc treatment), femur fracture in 1 subject (assessed as unrelated to rFVIIIFc treatment), death in 1 subject (fatal outcome of polysubstance overdose and completed suicide, assessed as unrelated to rFVIIIFc treatment), and arthralgia in 1 subject (assessed as related to rFVIIIFc treatment, but subject was recorded to have discontinued the study due to withdrawal of consent). Of the 3 subjects who discontinued for ”other” reasons, 1 subject was incarcerated, 1 subject was traveling and could not ensure proper temperature conditions for study treatment, and 1 subject was not willing to reveal the reason for wanting to complete the early termination visit.