Recombinant factor VIIa for the treatment of congenital factor VII deficiency.

Abstract

Factor VII deficiency is a rare autosomal bleeding disorder with a highly variable hemorrhagic predisposition. Severe bleeding, including hemarthroses, may be encountered when plasma factor VII levels are below 1%. Patients have prolonged prothrombin times, and the final diagnosis is established by quantitative factor VII assays. Some patients have true deficiencies, that is, very low factor VII activity and low factor VII antigen (cross-reacting material) levels (CRM-); others have normal antigen levels but low activity (CRM+). Still others have reduced antigen levels (CRMR). There is a rather poor correlation between clinical symptoms and factor VII activity levels in plasma. Treatment of these patients consists of fresh frozen plasma, prothrombin complex concentrates, or factor VII concentrates. Recombinant activated factor VII (rFVIIa) is a very useful alternative, and several patients have been treated successfully. Because of the short half-life of factor VIIa, repeated doses have to be administered, and continuous infusion may be even better. Antibodies to factor VII have been reported but seem to be rather rare. From the available data it appears that rFVIIa is a safe and effective treatment modality for patients with congenital factor VII deficiency.