A PROSPECTIVE-STUDY OF THE RISK OF TRANSFUSION-ACQUIRED VIRAL-INFECTIONS

The risk of transfusion-transmitted viral infections may be estimated by several methods, but only prospective studies of transfusion recipi ents can directly measure the incidence, with associated 95% upper con fidence bound, of these infections. From 1989 through 1995, 764 recipi ents of allogeneic or autologous red blood cell transfusions were enro lled; 486 (64%) provided both pretransfusion and 6-month follow-up spe cimens. Both specimens were tested for anti-HBc, anti-HCV, anti-HTLV-I and anti-HIV, with appropriate confirmatory testing. Thirty-nine (8.0 %) subjects had seroprevalent anti-HBc, 19 (3.9%) subjects had seropre valent anti-HCV, three (0.6%) subjects had seroprevalent anti-HTLV-I/I I, and one (0.2%) subject had seroprevalent anti-HIV. There were no se roconversions for any agent among the 34 patients who received only au tologous blood, and no confirmed seroconversions for anti-HTLV-I or an ti-HIV among all subjects. There were three seroconversions for anti-H Bc (incidence 1.04 x 10(-3). 95% confidence interval (Ci) 2.15 x 10(-4 ), 3.05 x 10(-3) per allogeneic unit transfused), and two confirmed se roconversions for HCV (incidence 6.94 x 10(-4); 95% CI 8.34 x 10(-5), 2.51 x 10(-3) per allogeneic unit transfused). One of the two anti-HCV seroconversions occurred in March 1994, after the institution of HCV EIA 2.0 screening of donated blood. Transfusion-associated seroconvers ions to hepatitis B and C markers were observed at low rates in the ea rly 1990s despite testing donors for markers of both viruses, whereas seroconversions to HTLV-I or HIV were less than 1.04 x 10(3) per allog eneic unit transfused, based upon the upper 95% confidence interval of the zero incidence in this study.