Study to Describe the Allergic Reactions to Factor IX in Patients With Hemophilia B

Retrospective, multicenter study in patients with hemophilia B. This study will be placed at 20 to 50 hemophilia treatment centers in North America and the EU, and is designed to estimate the frequency of Class II and III allergic reactions in association with the administration of any FIX concentrate.

Following informed consent and eligibility, historical patient information including demographics, allergy history, hemophilia history, frequency and severity of allergic reaction(s), number of exposure days with products causing allergic reactions, exposure days to blood products including FIX concentrates, treatment for allergic reaction(s), outcome of event(s), any other adverse event(s) occuring within 48 hours of onset of allergic reaction(s), rechallenge and outcome, switch to another FIX product (if applicable) and outcome, current status of patient, and results of any special studies (eg, skin or RAST testing, alloantibody analyses, ect) will be collected.