title: Frontloading: a risk factor for HIV and hepatitis C virus infection among injecting drug users in Berlin.
abstract: OBJECTIVE
  To determine whether frontloading (i.e., syringe-mediated drug-sharing) is a risk factor for HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) infection among injecting drug users (IDU).
  
  
  METHODS
  Cross-sectional study. Data on sociodemographic and behavioural characteristics were obtained by a standardized questionnaire. Serum samples were tested for seromarkers for HIV, HBV and HCV.
  
  
  METHODS
  IDU were recruited at 'low-threshold' storefront agencies (out-of-treatment sample), and at a centre for long-term drug use treatment (in-treatment sample). Individuals were included in the study if they had injected drugs within the previous 3 months.
  
  
  METHODS
  Serological evidence for HIV, HBV, HCV exposure.
  
  
  RESULTS
  Of all IDU (n = 324), 84% had ever practised frontloading with non-sterile injecting equipment, and 46% had done so more than 100 times; 32% had front-loaded during the 6 months prior to the interview. The crude seroprevalence rates for HIV, HBV and HCV increased with the overall frequency of frontloading, and reached 22, 71 and 94%, respectively, among IDU who had frontloaded more than 100 times. After controlling for confounding effects by logistic regression, having practised frontloading more than 100 times was significantly associated with HIV infection [adjusted prevalence odds ratio (POR) 3.5; 95% confidence interval (CI), 1.4-9], and HCV infection (adjusted POR, 5.4; 95% CI, 2.3-12), but not with HBV infection. Another independent risk factor for all three virus infections was needle-sharing in prison.
  
  
  CONCLUSIONS
  In communities where sterile injection equipment is readily available, and IDU have substantially reduced their overall levels of needle-sharing, the practice of frontloading appears to be a major risk factor for infections by blood-borne viruses among IDU. Prevention activities should specifically address this risk behaviour.
authors.affiliation: Institute of Tropical Medicine, Free University of Berlin, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Stark
authors.forename: R
authors.initials: R
authors.lastname: Müller
authors.forename: U
authors.initials: U
authors.lastname: Bienzle
authors.forename: I
authors.initials: I
authors.lastname: Guggenmoos-Holzmann
mesh_terms: D000328:Adult; D001604:Berlin / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D015658:HIV Infections / Q000150:complications / Q000453:epidemiology / Q000635:transmission*; D006509:Hepatitis B / Q000150:complications / Q000453:epidemiology / Q000635:transmission; D006526:Hepatitis C / Q000150:complications / Q000453:epidemiology / Q000635:transmission*; D006801:Humans; D008297:Male; D016485:Needle Sharing / Q000009:adverse effects*; D012307:Risk Factors; D015819:Substance Abuse, Intravenous / Q000150:complications*