CLINICAL CHARACTERIZATION OF A COMPETITIVE PCR ASSAY FOR QUANTITATIVETESTING OF HEPATITIS-C VIRUS

Rational clinical application of quantitative assessments of hepatitis C virus (HCV) RNA depends on an understanding of factors affecting th e assay and its intrinsic variability, The effects of three types of b lood collection tubes, two storage temperatures, five processing times , and two laboratories on a commercially available quantitative revers e transcriptase PCR assay (AMPLICOR HCV MONITOR) were evaluated. HCV R NA concentrations were assessed in 356 specimens representing 178 aliq uots from nine patients. In a multivariate generalized linear model, H CV RNA concentrations decreased when centrifugation was delayed more t han 6 h (P = 0.005) and were marginally different between laboratories (P = 0.06), but precentrifugation storage temperature (P = 1.00) and anticoagulation (P = 0.22) had no effect. After adjusting for other fa ctors, the HCV concentration of 95% of a subject's samples were within 0.44 log. Specimens procured for reverse transcriptase PCR-based quan titative HCV testing should be centrifuged within 6 h of collection. S erial assessments should ideally be performed in the same laboratory, and changes in HCV RNA concentration of less than 0.44 log may not be biologically important.