title: HCV seroconversion among never-injecting heroin users at baseline: no predictors identified other than starting injection.
abstract: BACKGROUND
  Heroin users who do not inject constitute a large pool of drug users with a potentially important impact on public health. We aimed to estimate the incidence of hepatitis C virus (HCV) among heroin users who had never injected (NIDUS) at baseline, and the effect of starting injecting during follow-up, other percutaneous exposures, sharing snorting paraphernalia, cocaine/crack use, and risky sexual behaviour on HCV-seroconversion.
  
  
  METHODS
  Prospective cohort of 305 HCV-negative NIDUs at baseline, aged 18-30 and street-recruited in three Spanish cities in 2001-2003. Computer-assisted personal interviews were conducted and dried blood-spot samples were collected. Bivariate and multivariable Poisson models were used.
  
  
  RESULTS
  Among the 305 never-injectors who were HCV-negative at baseline, 197 (64.6%) were followed-up and 21 seroconverted [HCV-incidence rate=5.8/100 person-years at risk (pyar) (95% CI: 3.6-8.9)]. HCV incidence in new-injectors was 28.4/100 pyar [(95% CI, 14.7-49.7) vs. 2.8/100 pyar (95% CI, 1.3-5.4)] among NIDUs. Of the risk exposures considered, starting injecting was the only predictor of HCV-seroconversion [adjusted relative risk=10.1, 95% CI: 3.8-26.7].
  
  
  CONCLUSIONS
  The HCV-seroconversion rate was 10 times higher among new-injectors than never-injectors. No predictors other than starting injecting were found for HCV-seroconversion. Harm reduction interventions to prevent HCV infection should include prevention of drug injection.
authors.affiliation: Centro Nacional De Epidemiología, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: María J
authors.initials: MJ
authors.lastname: Bravo
authors.forename: Fernando
authors.initials: F
authors.lastname: Vallejo
authors.forename: Gregorio
authors.initials: G
authors.lastname: Barrio
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Brugal
authors.forename: Gemma
authors.initials: G
authors.lastname: Molist
authors.forename: José
authors.initials: J
authors.lastname: Pulido
authors.forename: Luis
authors.initials: L
authors.lastname: Sordo
authors.forename: Luis
authors.initials: L
authors.lastname: de la Fuente
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D003625:Data Collection; D005260:Female; D005500:Follow-Up Studies; D006526:Hepatitis C / Q000453:epidemiology* / Q000209:etiology / Q000276:immunology; D006556:Heroin Dependence / Q000150:complications / Q000453:epidemiology*; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D016012:Poisson Distribution; D011446:Prospective Studies; D012306:Risk; D013030:Spain / Q000453:epidemiology; D015819:Substance Abuse, Intravenous / Q000150:complications / Q000453:epidemiology*; D055815:Young Adult