title: Reduction in HCV incidence among injection drug users attending needle and syringe programs in Australia: a linkage study.
abstract: OBJECTIVE
  We examined trends in HCV incident infection among injection drug users (IDUs) attending needle and syringe programs (NSPs) in Australia in 1995 to 2010.
  
  
  METHODS
  We created a passive retrospective cohort of 724 IDUs who tested negative for HCV antibodies by a simple deterministic method linking partial identifiers to find repeat respondents in annual cross-sectional serosurveillance.
  
  
  RESULTS
  We identified 180 HCV seroconversions over the study period, for a pooled incidence density of 17.0 per 100 person-years (95% confidence interval [CI] = 14.68, 19.66). Incidence density declined, from a high of 30.8 per 100 person-years (95% CI = 21.3, 44.6) in 2003 to a low of 4.0 (95% CI = 1.3, 12.3) in 2009.
  
  
  CONCLUSIONS
  A decline in HCV incidence among Australian IDUs attending NSPs coincided with considerable expansion of harm reduction programs and a likely reduction in the number of IDUs, associated with significant changes in drug markets. Our results demonstrate the capacity of repeat cross-sectional serosurveillance to monitor trends in HCV incidence and provide a platform from which to assess the impact of prevention and treatment interventions.
authors.affiliation: Kirby Institute, University of New South Wales, Sydney, Australia. jiversen@kirby.unsw.edu.au
authors.forename: Jenny
authors.initials: J
authors.lastname: Iversen
authors.forename: Handan
authors.initials: H
authors.lastname: Wand
authors.forename: Libby
authors.initials: L
authors.lastname: Topp
authors.forename: John
authors.initials: J
authors.lastname: Kaldor
authors.forename: Lisa
authors.initials: L
authors.lastname: Maher
mesh_terms: D001315:Australia / Q000453:epidemiology; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005260:Female; D006526:Hepatitis C / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission*; D006801:Humans; D015994:Incidence; D008297:Male; D018671:Needle-Exchange Programs; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D015819:Substance Abuse, Intravenous / Q000150:complications* / Q000453:epidemiology