Incidence of factor VIII inhibitor development in severe hemophilia A patients treated only with one brand of highly purified plasma-derived concentrate.

The incidence of factor VIII inhibitor was studied in a cohort of 56 previously untreated patients with severe hemophilia A (factor VIII below 1 U/dl). They received only one brand of highly purified factor VIII concentrate (HPSD-VIII) prepared by conventional chromatography with a solvent-detergent step for viral inactivation. Follow-up since the first infusion of HPSD-VIII was from 1 to 76 months (mean = 29) and cumulative exposure days (CED) from 1 to over 100 (median = 26). Five patients (9%) developed an inhibitor after 6 to 19 CED, only one being a high responder (2%), showing a low incidence of inhibitor compared with previous studies using high purity plasma-derived or recombinant products.