The journal Haemophilia has published the results of a six-year study called the Hemophilia Inhibitor Research Study (HIRS) that was designed to test the feasibility of conducting national monitoring for inhibitors among people with hemophilia in the United States.
The study collected blood specimens on a regular basis from study participants, which were tested at CDC for the presence of an inhibitor. Data were also collected to learn who was at highest risk for developing an inhibitor. Regular testing for an inhibitor is important because the treatment to get rid of the inhibitor is more successful when an inhibitor is identified early.
In the study, investigators from 17 hemophilia treatment centers located across the United States enrolled 1,163 people with hemophilia and followed them for up to 6 years to learn the best way to determine who was at risk for developing an inhibitor. HIRS investigators and CDC researchers found that people with hemophilia of all ages were at risk for developing an inhibitor and that unless people are regularly tested for an inhibitor, they can have one and not know it until it causes a severe bleeding problem.
Read the Hemophilia Inhibitor Research Study (HIRS) in its entirety
Main Findings from this Study:
- All people with hemophilia are at risk for developing inhibitors
- One-third of newly-developed inhibitors were found in people with non-severe hemophilia
- One-half were over the age 5 years
- One quarter had used infused factor for more than 150 days
- Six out of ten people with hemophilia with an inhibitor had no symptoms
- Regular screening of people with hemophilia for early detection of an inhibitor by the CDC laboratory is feasible, and will inform efforts to measure rates of this complication