[Risk factors for hepatitis C among injecting drug users in Oslo].

BACKGROUND: Hepatitis C virus (HCV) infection is common among injecting drug users. The aims of this study were to assess the prevalence of risk behaviour and its association with HCV infection.

MATERIAL AND METHODS: All users of the needle exchange program in Oslo, within a given time period, were eligible for inclusion in this cross-sectional study; 327 chose to participate. The users were asked about type of drug use and risk behaviour for HCV exposure in a structured interview. Sera were drawn and tested for anti HCV (EIA-3) and HCV RNA (in- house PCR).

RESULTS: The prevalence of HCV RNA was 51 % and 81 % had anti-HCV. A multivariate analysis revealed positive associations between anti-HCV positive status and age < 20 years at first injection, > 5 years of drug use, age > 34 years, sharing of syringes, injecting drug use while imprisoned, back-loading and use of heroin. One in five users with anti-HCV reported to never have shared syringes. However, sharing of drug paraphernalia other than needles was not associated with anti-HCV. Sharing of needles the last four weeks before the interview was more common among those living with a partner than those who lived alone.

INTERPRETATION: Most injecting drug users in Oslo have been exposed to HCV (anti HCV+) and half of them have developed chronic infection (HCV RNA+). HCV was associated with back-loading and sharing of syringes - especially during incarceration. Sharing of injection paraphernalia was not associated with being anti HCV positive.