title: Comparison of three commercially available assays for HCV RNA using the international unit standard: implications for management of patients with chronic hepatitis C virus infection in clinical practice.
abstract: OBJECTIVE
  The present study was performed to evaluate the impact of the international unit standard for measuring HCV RNA in the management of patients with chronic hepatitis C virus (HCV) infection.
  
  
  METHODS
  The three assays used were Amplicor Monitor PCR, the National Genetics Institute PCR assay, and branched chain DNA. HCV RNA was measured at four time points (baseline, 3 months after the start of therapy, at the end of treatment, and 6 months after discontinuation of therapy) in 106 consecutive patients who received interferon and ribavirin for chronic HCV.
  
  
  RESULTS
  The mean age of the patients was 44 yr. Of the patients, 62% were male, 24% were African American, 38% had bridging fibrosis or cirrhosis, and 75% were HCV genotype 1. Of the 424 samples analyzed, 82-89% of values were within 1 log unit and 85-92% were within 2 log units by the various assays. This variability was not dependent upon HCV genotype. HCV RNA was undetectable in 1.4-6.8% of samples when virus was detected by another assay. The mean HCV RNA in these discordant samples was 1.47-6.33 log IU/ml (30-2,100,000 IU/ml).
  
  
  CONCLUSIONS
  These data demonstrate that approximately 90% of serum values for HCV RNA were within 1 log unit by the international unit standard regardless of which virological assay was used. However, false positive and false negative results as well as variations in the HCV RNA level of more than 1 to 2 log units can occur with any of the assays, and these results may have an impact upon the management of patients receiving interferon therapy. It is therefore unwise in clinical practice to base important treatment decisions upon a single HCV RNA determination.
authors.affiliation: Hepatology Section, Virginia Commonwealth University Health System-Medical College of Virginia, Richmond, Virginia 23298, USA.
authors.forename: Mitchell L
authors.initials: ML
authors.lastname: Shiffman
authors.forename: Andrea
authors.initials: A
authors.lastname: Ferreira-Gonzalez
authors.forename: K Rajender
authors.initials: KR
authors.lastname: Reddy
authors.forename: Richard K
authors.initials: RK
authors.lastname: Sterling
authors.forename: Velimir A
authors.initials: VA
authors.lastname: Luketic
authors.forename: R Todd
authors.initials: RT
authors.lastname: Stravitz
authors.forename: Arun J
authors.initials: AJ
authors.lastname: Sanyal
authors.forename: Carleton T
authors.initials: CT
authors.lastname: Garrett
authors.forename: Maria
authors.initials: M
authors.lastname: De Medina
authors.forename: Eugene R
authors.initials: ER
authors.lastname: Schiff
mesh_terms: D000328:Adult; D000368:Aged; D000998:Antiviral Agents / Q000627:therapeutic use; D021121:Branched DNA Signal Amplification Assay / Q000379:methods; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D005838:Genotype; D016174:Hepacivirus / Q000235:genetics*; D019698:Hepatitis C, Chronic / Q000188:drug therapy / Q000821:virology*; D006801:Humans; D007394:International System of Units; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods; D012367:RNA, Viral / Q000032:analysis*; D012015:Reference Standards
chemical_list: D000998:Antiviral Agents; D012367:RNA, Viral