The impact of inhibitors on the cost of clotting factor replacement therapy in Haemophilia A in Canada.

A retrospective case controlled study was performed to determine the comparative costs of clotting factor concentrate therapy for haemophilia A patients with and without inhibitors. We examined treatment records for a 3.5-year period for nine patients with factor VIII inhibitors and nine noninhibitor control patients matched for age and severity of disease. Inhibitor patients used FEIBA, porcine factor VIII, recombinant factor VIIa, and recombinant factor VIII over the study period. Controls used recombinant factor VIII and small amounts of monoclonal antibody purified plasma-derived factor VIII and DDAVP. The total and mean cost for treating the nine inhibitor patients was 2.25-fold greater than the cost for treating the controls. However, in six of the nine pairs the replacement product costs were actually less for the control patient than for the inhibitor patient, and the median cost of concentrates was comparable in the two groups (CDN$150 686 and $133 342 for inhibitor and control patients, respectively). This discrepancy was largely accounted for by a single inhibitor patient who required frequent hospitalizations for severe bleeding episodes. This individual, who did not receive an immune tolerance protocol, accounted for 62% of the total costs for the entire inhibitor group. In summary, over the study period the cost of haemostatic therapy for most inhibitor patients did not exceed that of control patients. However, due to the high per-unit cost of the products used to treat inhibitor patients, the effect of individual outliers greatly magnifies the overall costs of treating patients with this complication.