Assessing Clinical Utility of Hepatitis C Virus Quantitative RT-PCR Data: Implications for Identification of Responders Among alpha-Interferon-treated Patients.
Background: Detection of hepatitis C virus (HCV) RNA in serum or plasma is currently the best means of identifying active HCV infection. In this study, we assessed the clinical utility of the HCV Amplicor Monitor (Roche Molecular Diagnostics, Branchburg, NJ) quantitative assay for monitoring viral burden and its implications for identifying responders among alpha-interferon-treated patients with chronic hepatitis C. Methods and Results: Precision and linearity were determined on aliquots of a pooled control serum. Error of the mean was normally distributed. The coefficient of variation of log10-transformed titers was 2%-6% over a range of 1.5 x 10(4)-1.5 x 10(5) copies/mL. Linearity over this range was high (R=.98-.99). Accuracy, as evaluated by comparison of split samples, showed that the Amplicor assay provided an unbiased estimate of the values from a reference laboratory. In a sample of 36 patients treated with alpha-interferon for chronic hepatitis C disease, mean viral titer declined with improvement of disease. The assay demonstrated heterogeneity among clinical responders with regard to their ability to actually clear their viral burden. Conclusions: Decreased viral burden as measured by the HCV Amplicor assay is potentially useful for monitoring individuals with HCV infection.