INTERPRETING SEROLOGIC TESTS FOR HEPATITIS-C VIRUS-INFECTION - BALANCING COST AND CLARITY

Although progress has been made toward developing a cheap and accurate method to diagnose hepatitis C virus (HCV) infection, current screeni ng tests have and unacceptably high false-positive rate. Newer tests a re more accurate, but also more costly. This paper outlines an approac h for interpreting and using these different tests. KEY POINTS The sec ond-generation enzyme-linked immunosorbent assay (ELISA) for HCV antib odies, the current screening test for HCV infection, has a sensitivity of approximately 90% but a low specificity. Persons with risk factors for HCV infection, elevated aminotransferase levels, and a positive E LISA result most likely have HCV infection. Confirmatory testing with a recombinant immunoblot assay adds considerably to the cost of diagno sis and should only be used to confirm HCV infection in ELISA-positive patients at low risk or with conditions such as hyperglobulinemia tha t promote false-positive reactivity. Polymerase chain reaction (PCR) t esting is the most sensitive and accurate method of diagnosing HCV inf ection, but its cost limits its use. PCR testing should be reserved fo r cases of diagnostic uncertainty, evaluation of possible acute hepati tis C, patients with normal serum aminotransferase levels and anti-HCV antibodies, and patients about undergo interferon therapy.