title: Hepatitis C virus incidence among injecting drug users on opioid replacement therapy.
abstract: OBJECTIVE
  To determine hepatitis C virus (HCV) incidence among injecting drug users (IDUs) receiving opioid replacement therapy (ORT).
  
  
  METHODS
  A retrospective cohort study was established in a primary care drug dependency treatment clinic. The cohort included all IDUs who commenced ORT after January 1996 with an initial anti-HCV antibody negative result and repeat testing prior to July 2003. HCV incidence was estimated for all subjects, with further comparison among those with continuous versus interrupted ORT.
  
  
  RESULTS
  Fifty-four subjects were initially HCV antibody negative and had repeat testing. Five cases of HCV antibody seroconversion occurred during a total follow-up period of 131.1 person years (py), an incidence of 3.8/100 py (95% CI 1.2-8.9/ 100 py). Four seroconversions occurred in the subgroup with interrupted ORT (n=20), an incidence of 7.4/100 py (95% CI 2.0-18.9/100 py), compared with one seroconversion in the subgroup with continuous ORT (n=34), an incidence of 1.3/100 py (95% CI 0.03-7.3/100 py).
  
  
  CONCLUSIONS
  HCV incidence among IDUs receiving ORT in our clinic was relatively low. Those IDUs without interruptions to their treatment appeared to be at particularly low risk of HCV infection. These findings support the role of ORT in HCV prevention for IDUs.
authors.affiliation: The Byrne Surgery, New South Wales.
authors.forename: Richard
authors.initials: R
authors.lastname: Hallinan
authors.forename: Andrew
authors.initials: A
authors.lastname: Byrne
authors.forename: Janaki
authors.initials: J
authors.lastname: Amin
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Dore
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage; D002047:Buprenorphine / Q000008:administration & dosage; D015331:Cohort Studies; D004359:Drug Therapy, Combination; D005260:Female; D006526:Hepatitis C / Q000097:blood / Q000453:epidemiology* / Q000821:virology; D018937:Hepatitis C Antibodies / Q000302:isolation & purification; D006801:Humans; D015994:Incidence; D008297:Male; D008691:Methadone / Q000008:administration & dosage; D008875:Middle Aged; D009517:New South Wales / Q000453:epidemiology; D012189:Retrospective Studies; D016036:Seroepidemiologic Studies; D016320:Substance Abuse Treatment Centers / Q000706:statistics & numerical data*; D015819:Substance Abuse, Intravenous / Q000188:drug therapy* / Q000453:epidemiology / Q000821:virology*
chemical_list: D000701:Analgesics, Opioid; D018937:Hepatitis C Antibodies; D002047:Buprenorphine; D008691:Methadone