Factor VIII Inhibitors and the Use of Blood Products in Patients with Haemophilia A

The occurrence of factor VIII inhibitors was investigated in 90 patients with haemophilia A. Inhibitors were found in 11 (12%) patients, all having severe haemophilia A. In 8 of these circulating anticoagulant activity was revealed by a screening method, which ten years earlier had disclosed anticoagulant activity in only one of 82 patients studied. The amount of blood products transfused to 62 patients with severe haemophilia A in the first study varied from 0 to 7, with a median of 0.9 plasma units per year of age. The values for 69 patients with severe haemophilia A in the present series were: range 0–87 and median 4.5 plasma units per year of age. The increased use of blood products was thus accompanied by an increased occurrence of factor VIII inhibitors. The patients with inhibitors did not differ from other patients with severe haemophilia A with respect to the amount of blood products given.