J Pillonel1, S Laperche. 1. Institut de veille sanitaire, 12, rue du Val-d'Osne, 94415 Saint-Maurice cedex, France.
Abstract
BACKGROUND: Monitoring trends in residual risk of transfusion-transmitted viral infections is important to assess improvements in blood safety. These trends were analysed over nine overlapping periods of 3 years from 1992 to 2002. The 2000-2002 estimates were compared to the results of HIV-1 and HCV NAT implemented on all blood donations in July 2001. METHOD: As risk is mainly associated with the window period, residual risks were estimated by multiplying incidence rates by the durations of the window periods. For the first seven periods, incidence rates were calculated from data collected by the blood centres belonging to the Transfusion-Transmissible Agents Working Group which collect more than 50% of blood donations in France, and for the two last periods, on the overall blood supply. RESULTS: On the 2000-2002 period, residual risks without NAT were estimated at 1 in 1,400,000 for HIV, at 1 in 1,000,000 for HCV and at 1 in 400,000 for HBV. With minipool NAT, the residual risk become nearly two times lower for HIV (1 in 2.5 million donations) and seven times lower for HCV (1 in 6.65 million donations). For HIV, of the 4.9 million donations screened with NAT between July 2001 and June 2003, two were remote thanks to the NAT, which is consistent with the NAT expected yield. Concerning HCV, one out of the four WP predicted cases was detected with NAT. Without NAT, the overall residual risk for the three viruses combined (HIV, HCV, HBV) decreased from 1 in 65,000 to 1 in 235,000 donations between 1992 and 2002. Since the implementation of NAT, the current overall residual risk is 1 in 325,000 donations (28% less than without NAT). CONCLUSION: NAT results confirm the validity of residual risk estimates given by the model, and the limited benefit of genomic screening due to the very low level of residual risk at the time of its implementation.
BACKGROUND: Monitoring trends in residual risk of transfusion-transmitted viral infections is important to assess improvements in blood safety. These trends were analysed over nine overlapping periods of 3 years from 1992 to 2002. The 2000-2002 estimates were compared to the results of HIV-1 and HCV NAT implemented on all blood donations in July 2001. METHOD: As risk is mainly associated with the window period, residual risks were estimated by multiplying incidence rates by the durations of the window periods. For the first seven periods, incidence rates were calculated from data collected by the blood centres belonging to the Transfusion-Transmissible Agents Working Group which collect more than 50% of blood donations in France, and for the two last periods, on the overall blood supply. RESULTS: On the 2000-2002 period, residual risks without NAT were estimated at 1 in 1,400,000 for HIV, at 1 in 1,000,000 for HCV and at 1 in 400,000 for HBV. With minipool NAT, the residual risk become nearly two times lower for HIV (1 in 2.5 million donations) and seven times lower for HCV (1 in 6.65 million donations). For HIV, of the 4.9 million donations screened with NAT between July 2001 and June 2003, two were remote thanks to the NAT, which is consistent with the NAT expected yield. Concerning HCV, one out of the four WP predicted cases was detected with NAT. Without NAT, the overall residual risk for the three viruses combined (HIV, HCV, HBV) decreased from 1 in 65,000 to 1 in 235,000 donations between 1992 and 2002. Since the implementation of NAT, the current overall residual risk is 1 in 325,000 donations (28% less than without NAT). CONCLUSION:NAT results confirm the validity of residual risk estimates given by the model, and the limited benefit of genomic screening due to the very low level of residual risk at the time of its implementation.