Performance of Hepatitis C virus (HCV) antibody test systems in relation to HCV-RNA detection in the diagnosis of HCV infection

Background: Hepatitis C virus antibody (anti-HCV) test systems for screening and conformation of blood donations have proved their value. The systems were later adopted for diagnosing patients suspected of hepatitis C. Objectives: 1) to study the clinical value of the recombinant immunoblot assay (RIBA) in routine diagnostics of patients suspected of HCV infection using HCV-PCR as the most definitive test and 2) to compare the performance of RIBA-2 with RIBA-3. Materials: From May 1991 to August 1996 more than 4300 patients were tested for anti-HCV. All anti-HCV (EIA) positive patients were tested with RIBA-2 or RIBA-3 and HCV-PCR. Results: We found no difference in the overall performance of RIBA-2 compared to RIBA-3. There was a tendency to fewer indeterminate results using RIBA-3 compared to RIBA-2 (5% vs. 9%), but this was not statistically significant. The NS5 band in RIBA-3 did not improve sensitivity or predictive value. Of RIBA-2 and RIBA-3 positive patients, 71% and 66% respectively were found to be HCV-RNA positive. Two samples that were negative using RIBA were HCV-RNA positive. Conclusion: RIBA testing in anti-HCV (EIA) positive patients added no clinically useful information to the screening results. We have therefore changed the diagnostic strategy so that all anti-HCV (EIA) positive patients are tested for HCV-RNA.