Inhibitors in Patients with with Non-Severe Hemophilia A
Development of Inhibitors in Patients with Mild or Moderate Hemophilia A
HTRS 2015 (New Orleans, April 16-18) While patients with severe hemophilia A develop antibodies or inhibitors to factor VIII in over ¼ of patients, patients with mild or moderate hemophilia A can also develop inhibitors against factor therapy, according to data presented at the Hemostasis and Thrombosis Research Society (HTRS) 2015 Meeting. Just like in patients with severe hemophilia A, the risk factor for the development of inhibitors includes: number of exposure days, genotype, treatment intensity and age, but the rate of inhibitors is lower (1 in every 10-20 patients). Even the clinical presentation of inhibitor development is similar in patients with mild and moderate hemophilia A, and typically includes change in bleeding patterns, bleeding in the soft tissues, muscles, mucous membranes or joints and unresponsiveness to factor treatment. In two single center retrospective studies, 8 out of 36 and 10 out of 138 patients with mild and moderate hemophilia A receiving FVIII replacement therapy were found to test positive for inhibitors. In mild and -moderate hemophilia A, there is no link of inhibitor development with patients’ race/ethnicity, FVIII level or a particular factor product used. To avoid development of inhibitors, prevention is the best strategy; patients diagnosed with mild and moderate hemophilia A are often recommended to try alternatives to factor first to see if their body responds to it and use it to treat bleeding episodes instead of initiating factor products. Also they could get genetic testing done which may help with predicting the patient’s risk for inhibitor formation.