Haemophilia therapy: assessing the cumulative risk of HIV exposure by cryoprecipitate

Most of the world's haemophilia population live in countries with developin g or emerging economies. As such, they do not have access to viral inactiva ted clotting product. Many are treated with cryoprecipitate made from local ly supplied blood. The rationale for using cryoprecipitate instead of viral inactivated products is based on an implicit belief that because blood ban ks can provide reasonably safe products by using modern testing procedures, transmission of HIV and other blood-borne viruses is rare. However, the ri sk of acquiring a blood-borne infection is cumulative, and haemophilia pati ents treated with cryoprecipitate or fresh-frozen plasma are exposed to hun dreds or thousands of donors during their lifetime. The risk that an HIV-in fected person will be a donor during the 'window period' is directly relate d to the incidence of HIV in the country where the donation occurs. To illu strate the extent of this problem, we devise a model for estimating the ris k that a person with haemophilia will encounter HIV-contaminated cryoprecip itate as a function of years of treatment and the underlying incidence rate of HIV among blood donors. We apply the model to two countries with differ ent incidence rates of HIV, Venezuela and the USA. Over a lifetime of treat ment (60 years), the cumulative risk of HIV exposure for a person with haem ophilia receiving monthly infusion of cryoprecipitate prepared from plasma of 15 donors is significant, 2% in the USA and 40% in Venezuela. Considerin g the cumulative risk for transmitting HIV to patients with haemophilia thr ough cryoprecipitate treatment, medical care providers should carefully eva luate the use of cryoprecipitate in any but emergency conditions or when no virally inactivated products are available.