Approaching the ideal: therapeutic requirements for factor VIII concentrates

The requirements that a factor VIII concentrate should fulfil, as adopted by the Belgian Health Council, are reviewed. Lack of immunogenicity is an important issue; the Belgian experience suggests that a prospective randomized trial allows rather rapid detection of grossly increased immunogenicity. An alternative is provided by prospective cohort studies, using a uniform protocol to evaluate the behavior of each product, and an independent data monitoring centre. Residual infectivity is illustrated by an outbreak of hepatitis A in heavily treated patients. A prospective randomized trial in Belgium is planned to evaluate the benefits and risks of a double-virus inactivated product.