The Effect of Factor Activity Levels and Bleeding Characteristics

Relations between Factor Activity Level and Joint Bleeding in a Large Cohort of Males with Mild and Moderate Hemophilia in the United States

ISTH 2015 (Toronto, June 20-25) An oral presentation at the International Society on Thrombosis and Hemostasis (ISTH) 2015 Meeting discussed the relationship between factor activity levels and joint bleeding in males with mild and moderate hemophilia in the United States. During the study, clinical information was collected on 4771 patients from a total of 19,979 clinic visits. The results showed that the average joint bleed rate was significantly lower in hemophilia B than A (1.4 vs 0.7 bleeds) after adjusting for factor activity levels and other risk factors. Hemophilia B patients with similar factor activity levels and risk factors are 33% less likely to have an invasive orthopedic procedure. The “typical” 25-44 year old hemophilia A patient with factor activity level of 20% was predicted to have 1 joint bleed/year compared to 1 joint bleed/every other year in a hemophilia B patient. In the US, the 15% factor activity level is not expected to prevent all joint bleeding episodes as reported in other patient populations.