[Retrospective study of the value of the RIBA-3 test in 68 patients with discordant serologies with regard to hepatitis C obtained with third generation ELISA tests. Is there still a value in RIBA-3?].

The aim of the present study is to evaluate the ability of RIBA-3 to resolve cases with controversial ELISA results, since modifications have been introduced by the manufacturer in July 1997 to analyse immunoblot patterns. Sera from 68 patients are studied: 49 controversial cases Ortho/Murex, 17 Ortho/Abbott and 2 cases tested by the three ELISA kits. Indeterminate patterns by ELISA assays remain unresolved in 65% of the samples. RIBA analysis performed in patients with controversial results Ortho/Murex seems to reveal a lack in sensitivity of the Murex kit, but does not show differences in the specificity between these two immunoassays. The RIBA patterns among the samples with Ortho/Abbott controversial results do not demonstrate any discrepancy in the sensitivity of these ELISA tests but it appears that Ortho could be less specific. Our data need to be further confirmed by the analysis of more samples. At last, when the ELISA result is included in the grayzone, the RIBA pattern is generally indeterminate and it is negative in other cases. Finally, the controversial ELISA results, that are mainly found in patients with severe immunosuppression, remain indeterminate depending on the RIBA test. Moreover, the immunoblot is less sensitive and more expensive than any other HCV ELISA test, so there is no convenience to use it for confirmation of a preliminary positive or indeterminate screening.