[False positives and false negatives seen in anti-HIV-1 antibody tests]

From September 1986 to December 1993 31059 anti-HIV antibody tests were performed on the samples from our clinic, from 29 health centers and their branches of Osaka Prefecture, from a hospital and from high risk groups. Enzyme immune assay (EIA) was used up to 1988 and from 1989 particle agglutination (PA) has been employed. The indeterminates of Western blot (WB) were seen in 5 EIA positives and in 2 PA positives. False positive rate of EIA was 0.235% (11/467) and that of PA was 0.011% (2/17922). Two false negative cases of anti-HIV-1 antibody test due to window period were documented and the importance of co-use of antigen test at the time of confirmative antibody tests was discussed.