A comparison of the performance of nine commercially available anti-HTLV-I screening assays.

The performance of eight anti-HTLV-I enzyme immunoassays (EIAs) and one particle agglutination assay was compared with respect to sensitivity, specificity and delta values, by testing a panel containing 99 anti-HTLV-I positive and 126 anti-HTLV-I negative samples which had been characterised by western blot and some by radioimmunoprecipitation assay. The estimated sensitivities produced by these assays ranged between 99% and 100% and estimated specificities were between 95.2% and 100%. The performance of the EIAs was further differentiated by using the delta value which measures the ability of an assay to separate the positive and negative populations from the cutoff value. A delta value could not be calculated for the particle agglutination assay (Serodia) because the test readings were not quantitative. The EIAs most likely to correctly identify anti-HTLV-I positive and anti-HTLV-I negative samples included the Cambridge Biotech, Dupont, Genetic Systems and Olympus assays. Our findings suggest that there may be some difficulty in correctly identifying anti-HTLV-I negative samples using the Abbott, Cellular Products Incorporated (CPI), Coulter and Diagnostic Biotechnology assays. The Serodia assay produced comparable sensitivity and specificity to the eight EIAs.