▪Objective: To evaluate the effectiveness of serologic testing of blood donors for human immunodeficiency virus type 1 (HIV-1) and human T-cell lymphotropic virus types I and Il (HTLV-I/II) infections and to estimate the risk for transmission of HIV-1 and HTLV-I/II by transfusion of seronegative blood from screened donors.
▪Design: A prospective multicenter cohort study of cardiac surgery patients who received multiple transfusions between 1985 and 1991.
▪Setting: Cardiac surgery services of three large tertiary care hospitals.
▪Patients: The study included 11 532 patients in three hospitals who had cardiovascular surgery.
▪Measurements: Incident HIV-1 and HTLV-I or HTLV-II infection.
▪Results: We detected two new HIV-1 infections among patients transfused with 120 312 units of blood components from seronegative donors. In each case a donor was detected on follow-up who had seroconverted since the donation. The HIV-1 infection rate was 0.0017% with an upper limit of the 95% Cl of 0.0053%. Before donor screening for HTLV-I, transfusion of 51 026 units resulted in two HTLV-I infections (0.0039%) and four HTLV-II infections (0.0078%). After HTLV-I screening was instituted, one recipient was infected with HTLV-II among participants exposed to 69 272 units, a rate of 0.0014%. A corresponding HTLV-l/ll-infecteddonor was found for this patient.
▪Conclusion: Serologic screening of donors for antibodies to HIV-1 and HTLV-I coupled with exclusion of donors from groups having a relatively high risk for infection has led to a low incidence of transfusion-transmittedHIV-1 and HTLV-I/II infection in the United States. A small risk remains, however, despite these measures. We estimate the residual risk for HIV-1 and HTLV-II infection from transfusion of screened blood during the time of this study to be about 1 in 60 000 units.