title: Accordion Index: A new tool for the prediction of the efficacy of peg-interferon-alpha-2b and ribavirin combination therapy for chronic hepatitis C.
abstract: OBJECTIVE
  An optimal treatment regimen based on individual virological response is essential to maximize the efficiency of interferon (IFN) therapy for chronic hepatitis C.
  
  
  METHODS
  Using indicators of the virological response and the treatment intensity, we developed the Accordion Index as a new tool for the efficacy prediction of peg-IFN and ribavirin (RBV) combination therapy. For the Accordion Index, the IFN-AC ratio and RBV-AC ratio were defined as follows: IFN-AC ratio = (total IFN dose given during the entire treatment period)/(total IFN dose required to achieve hepatitis C virus [HCV]-RNA negativity), RBV-AC ratio = (total RBV dose given during the entire treatment period)/(total RBV dose required to achieve HCV-RNA negativity).
  
  
  RESULTS
  The analysis of the association between the Accordion Index and the sustained virological response (SVR)revealed that of 25 patients who had HCV-RNA negativity during treatment, all 10 patients with an IFN-AC ratio and RBV-AC ratio of at least 4.0 achieved SVR, while only four of 15 patients with an IFN-AC ratio or RBV-AC ratio of less than 4.0 achieved SVR. With the cut-off value for both the IFN-AC ratio and RBV-AC ratio at 4.0 or higher, the quality of SVR prediction was as follows: the positive predictive value was 100%, the negative predictive value was 73.3%, and accuracy was 84.0%.
  
  
  CONCLUSIONS
  The Accordion Index will thus be a useful tool for planning optimal treatment regimens for individual patients.
authors.affiliation: Center for Liver Diseases and Department of Clinical Research, National Hospital Organization Kokura Hospital, Kitakyushu, Japan.
authors.forename: Takeaki
authors.initials: T
authors.lastname: Satoh
authors.forename: Akihide
authors.initials: A
authors.lastname: Masumoto