The majority of direct costs associated with caring for patients with hemophilia are attributed to replacement therapy with clotting factor concentrates (CFC). For patients who develop high-titer inhibitors, CFC are ineffective and bypassing therapy is used to achieve hemostasis, thus changing the direct costs associated with treatment. As bypassing agents are less predictably effective than CFC (often necessitating more frequent dosing) and are more costly on a per-unit basis, treatment costs for patients with inhibitors are usually much higher than those for patients without inhibitors. In addition, the immune tolerance induction protocols used to eradicate inhibitors are costly due to the frequent dosing of CFC over prolonged periods. It is estimated that the cost of hemostatic therapy for patients with inhibitors can be 2.5 times higher than the cost for patients without inhibitors. However, some studies have reported an outlier effect caused by a small percentage of inhibitor patients who require a disproportionate amount of treatment. These outliers magnify overall treatment costs, making cost assessments for hemostatic therapy less predictable in patients with inhibitors than in those without inhibitors.