Clinical utility and characteristics of nine anti-HCV antibody screening reagents used in Japan.

Nine anti-HCV antibody screening reagents currently used in Japan were investigated for diagnostic utility. The results using sera from 500 subjects and two series of anti-HCV seroconversion panels were compared. The positive detection rates of the 9 screening tests in 500 specimens ranged from 9.6% to 12.2% and the agreements between combinations ranged from 97.0-99.4%. In the 7 two-step assays, which employ recombinant antigen solid phase and anti-human antibody detection, i.e. excluding Quick Chaser and PA, agreement ranged from 97.6-99.4%. No relationship was seen between similarities of the antigen used and agreements between the 7 reagents. For the 72 specimens that showed positive with at least one screening reagent, agreements between the 9 reagents and the confirmatory tests (RIBA III) were compared. In specimens that showed positive with multiple reagents, the positive rate of RIBA III was high, thus the possibility of the existence of the anti-HCV antibody was high. In specimens that showed positive in only a single screening reagent, the RIBA III did not test positive, suggesting that the incidence of false positives may be high. The accuracy of each screening reagent was compared to RIBA III as an accuracy standard. It was found that ARCHITECT was the best in accuracy. The distance from mean to cut-off in the anti-HCV antibody negative specimens reflected the incidence of false positives in each reagent. The anti-HCV antibody seroconversion sensitivities in the initial stage of HCV infection were also compared. The earlier detection was seen with Centaur, ELISA and ARCHITECT. Each anti-HCV antibody screening reagent in use has unique features, and it is suggested that caution be used when diagnosing HCV infection on the basis of the results of a single antibody test.