Diagnosis of chronic hepatitis C: comparison of immunoassays and the polymerase chain reaction.

We evaluated a series of first- and second-generation enzyme-linked immunoassays for anti-HCV and compared the findings to those with two confirmatory assays, the recombinant immunoblot assay and serum HCV RNA, in patients with chronic hepatitis C, primary biliary cirrhosis, and chronic hepatitis B. All second-generation immunoassays had good sensitivities (98-100%). Interestingly, detection of HCV RNA had a sensitivity of only 93%, although it was 100% specific. The recombinant immunoblot assay and a peptide-based immunoassay also had good specificity (97% and 100%, respectively), whereas the second-generation immunoassay based on recombinant proteins had a high rate of false positivity, particularly among patients with primary biliary cirrhosis and hyperglobulinemia (specificity 68%). Thus, the diagnosis of HCV infection appears to require the use of more than one test. Whereas a second-generation enzyme-linked immunoassay can be used as an initial test, a confirmatory test (such as recombinant immunoblot assay or determination of hepatitis C viral RNA) may be required if the diagnosis remains uncertain.