Background: Eleven percent of severe hemophilia A patients and 5% of severe hemophilia B patients may develop inhibitors. We have conducted aPCC-based maintenance therapy for hemophilia patients with high levels of responding inhibitors and we analyzed the efficacy, safety, the factor consumption and the expense of this treatment, as compared to on-demand therapy.
Methods: Eleven hemophilia patients with high levels of responding inhibitors were eligible for the study. We tried to evaluate the longitudinal bleeding episodes, the inhibitor titers, the X-ray findings, the adverse events and the factor consumption between on-demand therapy and maintenance therapy. The bypassing agent in this study was aPCC having a longer half-life. The dosage was 30∼50 U/kg, 3 times a week.
Results: The mean follow-up period was 6.8 months for on-demand therapy and 10.6 months for maintenance therapy. The mean dosage of aPCC was 45.2 U/kg. The episodes of hemarthrosis decreased by 61.4% (P=0.003) and other significant bleedings decreased by 45.2% (P=0.109). The inhibitor titers decreased in 7 patients and these increased in 4 patients, but anamnesis took place in only 1 patient. Radiologically, 2 patients improved, 1 patient got worse and 7 patients were stable. Neither adverse signs nor symptoms were noticed. The mean factor consumption changed from 55.8×10³ U for aPCC and 48.6 mg for rFVIIa on-demand therapy to 216×10³ U for aPCC and 4.8 mg rFVIIa for maintenance therapy. Maintenance therapy cost 67% more than on-demand therapy monthly (P=0.041).
Conclusion: aPCC-based maintenance therapy for hemophilia patients with high responding inhibitors cost 67% more than on-demand therapy, but it reduced by 61.4% the episodes of hemarthrosis and 45.2% of the other significant bleedings. aPCC-based maintenance therapy can very effectively reduce the bleeding episodes of hemophilia patients with high levels of responding inhibitors. (Korean J Hematol 2009;44:205-211.)

Keywords: Hemophilia, Inhibitor, aPCC, Maintenance therapy