RISK OF INHIBITOR DEVELOPMENT WITH FACTOR -VIII AND FACTOR-IX - REVIEW OF THE LITERATURE

Factors VIII and IX administration exposes haemophiliac patients to th e risk of inhibitor development which reduces treatment efficacy. Meth ods and results of 17 studies (transversal and longitudinal) and of on e clinical trial dealing with haemophilia A and of 3 studies dealing w ith haemophilia B were reviewed. Besides differences in study design, lack of method standardisation complicates comparison between studies. In patients with haemophilia A, prevalence of inhibitors ranges from 4 to 18% (5 studies), and incidence between 3 and 39/1,000 person-year s (7 studies). Cumulative age incidence is above or equal to 20% after 6 years of age (4 studies). Cumulative incidence by exposure days is estimated at 22% at 100 exposure days in a retrospective cohort observ ed between 1975 and 1992, and above or equal to 36% at 25 exposure day s in two prospective cohorts of patients receiving recombinant factor VIII products. The new European regulation dealing with stable blood p roducts will make the evaluation of new products by clinical trials ma ndatory. With The National therapeutic Follow up of Haemophiliacs whic h begun in October 1994, following a decision by the French Minister o f Health, the adverse effects in patients receiving factor VIII and IX which have been approved for sales will be evaluated.