Predicting the long-term risk of HIV exposure by cryoprecipitate

Most of the world's haemophilia population lives in countries with few medi cal or financial resources. As such, they cannot easily obtain viral-inacti vated clotting product. Many patients are treated with cryoprecipitate made from locally supplied blood. The reasoning for using cryoprecipitate, inst ead of viral-inactivated products, is based on an unspoken belief that beca use blood banks can provide reasonably safe products by using modern testin g procedures, transmission of HIV and other blood-borne viruses is rare. Ho wever, the risk of acquiring a blood-borne infection increases with every e xposure, and haemophilia patients treated with cryoprecipitate or fresh-fro zen plasma are exposed to hundreds or thousands of donors during their life time. The risk that a person infected with HIV will donate blood during the 'window period' is directly related to the incidence of HIV in the country where the donation occurs. To demonstrate the extent of this problem, we d evised a model for estimating the risk that a person with haemophilia will encounter HIV-contaminated cryoprecipitate based on the years of treatment and the underlying incidence rate of HIV among blood donors. We applied the model to two countries with different incidence rates of HIV: Venezuela an d the United States. We found that a person with haemophilia who receives m onthly infusions of cryoprecipitate prepared from plasma of 15 donors over a lifetime of treatment (60 years) is at significant risk of being exposed to HIV. In the United States there is a 2% risk of being exposed to HIV-con taminated blood product, and in Venezuela, the percentage of risk is 40%. G iven this degree of risk, medical care providers should carefully evaluate the use of cryoprecipitate except in emergencies or when no viral-inactivat ed products are available.