title: Rapid virologic response: a new milestone in the management of chronic hepatitis C.
abstract: BACKGROUND
  Rapid virologic response (RVR), defined as an undetectable serum hepatitis C virus (HCV) RNA level at week 4 of treatment, is emerging as an important milestone in the treatment of patients who have chronic hepatitis C by use of pegylated interferon-alfa and ribavirin--the current standard of care. This assessment is being used to individualize treatment duration, which is currently recommended as 48 weeks in patients infected with HCV genotype 1 (G1) and 24 weeks in those infected with HCV G2 or G3.
  
  
  METHODS
  We collated information from studies including assessment of HCV RNA level at week 4, specifically highlighting the relationship between RVR and other predictors of treatment outcome and the manner in which RVR can be used to optimize treatment outcomes for specific patient groups.
  
  
  RESULTS
  The role of RVR in the treatment of patients with chronic hepatitis C varies according to viral genotype. Among patients with HCV G2/G3 infection, several studies have shown that shortening the treatment duration to 12-16 weeks is effective among those who attain RVR. In contrast, RVR may be used as an indicator for both shortened and extended treatment durations among patients with HCV G1 infection. HCV G1-infected patients with low baseline viral load who attain RVR may be effectively treated for 24 weeks, whereas patients who do not attain RVR may be candidates for an extended 72-week regimen.
  
  
  CONCLUSIONS
  RVR is rapidly becoming a new tool for predicting treatment outcomes in patients with chronic hepatitis C and represents a key opportunity to individualize therapy according to treatment-related viral kinetics.
authors.affiliation: Hepatology and Liver Transplantation, Cedars-Sinai Medical Center, Los Angeles, California 90048, USA. Fred.Poordad@cshs.org
authors.forename: Fred
authors.initials: F
authors.lastname: Poordad
authors.forename: K Rajender
authors.initials: KR
authors.lastname: Reddy
authors.forename: Paul
authors.initials: P
authors.lastname: Martin
mesh_terms: D000998:Antiviral Agents / Q000627:therapeutic use*; D016174:Hepacivirus / Q000235:genetics / Q000254:growth & development*; D019698:Hepatitis C, Chronic / Q000188:drug therapy* / Q000821:virology*; D006801:Humans; D016898:Interferon-alpha / Q000627:therapeutic use; D012367:RNA, Viral / Q000097:blood; D012254:Ribavirin / Q000627:therapeutic use; D016896:Treatment Outcome; D019562:Viral Load
chemical_list: D000998:Antiviral Agents; D016898:Interferon-alpha; D012367:RNA, Viral; D012254:Ribavirin