Complications of clotting factor replacement therapy

Blood borne diseases

Clotting factors may be concentrated and separated from human blood products – this type of product is called a cryoprecipitate. In the past this was the only type of clotting factor available. Unfortunately many of these products were contaminated with human blood borne viruses. Consequently many haemophiliacs became infected with one or more of the following viruses -:

• HIV
• Hepatitis B
• Hepatitis C

Refer to separate guidance on the treatment and disabling effects of these conditions.

Currently the majority of clotting factors are manufactured using recombinant techniques and there is no risk of disease transmission with these products. Human derived products are occasionally used e.g. in von Willebrand’s disease and techniques have been developed to prevent transmission of virus. No Haemophilia patient has developed HIV after 1984 or hepatitis C after 1991 through infected blood products.

Development of Inhibitor

Inhibitors are antibodies to clotting factors VIII and IX. They are made by the body’s immune system and attack and destroy the factor VIII and IX proteins in clotting factor concentrates, making treatment ineffective. It is most common in people with severe Haemophilia A. Treatment is available and the aim of treatment is to stop the body producing inhibitor. Treatment involves intensive high dose treatment with the clotting factor concerned and sometimes immuno-modulating drugs. The therapy regimen may involve the use of daily or twice daily injections of factor concentrate for a year or more. The inhibitor cannot always be treated and in these cases factor concentrate does not work. Other treatments can be given that help to stop bleeding but they are less effective. Progressive joint damage is likely and disability is likely to be greater in someone with an inhibitor than in someone without. Around 5% of people with haemophilia will have an inhibitor.

Amended November 2009