Cooperative Study of Factor VIII Inhibitors

To test the efficacy of prothrombin complex concentrates (Factor IX) in the treatment of hemophiliac patients who had inhibitors to Factor VIII.

BACKGROUND: Despite major advances in the treatment of patients with hemophilia, a serious remaining challenge was presented by the occurrence of circulating inhibitors to Factor VIII. Because of lack of information on the natural course of patients with Factor VIII inhibitors, the relative efficacy of various modes of therapy was not established. The Division of Blood Diseases and Resources decided to sponsor a clinical investigation which would evaluate populations of hemophilia patients for Factor VIII inhibitors, follow up these patients to provide information on the natural history of the inhibitor in the hemophilia patients, and make available a reference center to monitor results and attain uniformity. Treatment of a patient with a severe inhibitor and consequent bleeding remained a problem. Management included protracted treatment with Factor VIII, use of immunosuppressive agents and prothrombin complex (or Factor IX) concentrates. The rationale for Factor IX was that it bypassed the defect in Factor VIII caused by the inhibitor. This method of therapy attracted wide popularity, but the success was greatly debated. It was intended at the very outset of the Factor VIII study that therapeutic trials involving patients with inhibitors would not be a prime function, but that such studies would be monitored if necessary. A controlled trial of Factor IX concentrates therapy was strongly advised by the DBDR Advisory Committee. Accordingly, during fiscal year 1978, a protocol for a double-blind control study was developed by the Factor VIII inhibitor group. The trial began in the spring of 1978, and the intervention terminated about one year later. DESIGN NARRATIVE: Double-blind study; patients served as their own controls. A total of 51 patients each received a single large dose of Konyne, Proplex, or diluted albumin (as a control). Joint bleeding of the elbow, knee, and ankle was evaluated six hours after each dose.

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