High cost, low volume care in haemophilia

Editor—I contest the statement of Lee et al that “there is no hard information on the benefits of using recombinant factors over plasma derived concentrate.”¹ An independent review of haemophilia commissioned by the directors of public health in South Thames last year endorsed the recommendations of the United Kingdom Haemophilia Centre Directors Organisation about choosing recombinant factor VIII on the grounds of viral safety.²

The reason for this recommendation is the possibility of unknown viruses. At least one virus affecting humans, parvovirus B19, survives the purification processes for making factor VIII from plasma, even in the most purified products. Parvovirus itself rarely has clinical significance, but it is important as a marker for another as yet undetected virus.

Two main strategies are used to inactivate viruses in plasma products: heat treatment and solvent or detergent treatment to inactivate viruses with lipid envelopes—for example, hepatitis A virus. However, recent outbreaks of hepatitis A indicate that these methods are not always successful,³ particularly if a starting pool of plasma is infected by a unit of plasma containing high concentrations of virus.

Hard evidence also exists of the transmission of parvovirus B19 by factor VIII treated by both methods.⁴ One study traces the progression of acute parvovirus infection in haemophilic patients treated with plasma derived factor VIII through to seroconversion to IgM and later IgG antibodies.⁵

I think that the evidence adds up to more than biological plausibility and that the marginal increase in cost is justified, particularly in children.