Study design. Subjects were enrolled into 1 of 4 treatment arms: (1) PK50 + treatment: crossover PK at a dose of 50 IU/kg VWF:RCo followed by 12 months of on-demand bleed treatment; (2) PK50 only: crossover PK at a dose of 50 IU/kg VWF:RCo; (3) PK80 + treatment: PK at a dose of 80 IU/kg VWF:RCo repeated after 6 months, followed by 6 months of on-demand bleed treatment; and (4) treatment only: 12 months of on-demand treatment. R, randomized.