Formation of antibodies to factor VIII in patients with hemophilia A who are treated with interferon for chronic hepatitis C

Objective: To evaluate the risk for development of antibodies to factor VIII (factor VIII inhibitors) during and after interferon therapy in patients with hemophilia A and chronic hepatitis C infection. Design: Patients were divided into two treatment groups and an untreated control group. Test results from the two treatment groups were compared with those from the control group. Setting: 3 clinical centers in the Netherlands. Patients: 35 men with hemophilia A who had acquired hepatitis C through the use of plasma-derived clotting factor concentrates, Measurements: Patients were tested for factor VIII inhibitors before the start of interferon therapy and every 6 months thereafter. Results: 21 patients with hemophilia A received interferon therapy for chronic hepatitis C infection for a mean of 19.5 months (range, 0.5 to 36 months). In 2 patients, inhibitors were detected on one occasion (maximum titer, 1.2 Bethesda units/mL) during interferon therapy. In 3 patients who were known to have had inhibitors before interferon therapy, no anamnestic reaction was seen during treatment. In 3 of 14 untreated controls who were followed for a mean of 28 months (range, 18 to 40 months), inhibitors were detected on one occasion (maximum titer, 2.3 Bethesda units/mL). Conclusion: Long-term interferon therapy in patients with hemophilia did not increase the risk for development of factor VIII inhibitors.