These patients (n=59; median age 10 ± 8.3 months) had a mean incremental recovery at Week 0 of 1.5 ± 0.6 IU/ dl per IU/ kg (range 0.2 to 2.8 IU/ dl per IU/ kg) which was lower than that obtained in PTPs treated with ReFacto at Week 0 with a mean K-value of 2.4 ± 0.4 IU/ dl per IU/ kg (range 1.1 to 3.8 IU/ dl per IU/ kg).