Prevalence of hepatitis C virus infection among injecting drug users in Glasgow 1990-1996: are current harm reduction strategies working?

OBJECTIVES: To determine the prevalence of HCV antibodies among injecting drug users and to gauge the effectiveness of needle/syringe exchange in preventing the transmission of HCV infection.

METHODS: Between 1990-1994 and in 1996, annual cross-sectional surveys of injecting drug users in Glasgow were conducted. In order to ensure as representative a sample as possible, the 1949 respondents were recruited from both 'in-treatment' and 'out-of treatment' settings. Injectors were interviewed about their risk behaviours for blood-borne viruses and provided a saliva sample which was initially tested, anonymously, for HIV antibodies, and subsequently tested for hepatitis C infection.

RESULTS: Among 1949 injectors, the prevalence of salivary antibodies, indicative of hepatitis C viraemia, was 61%(95%, confidence interval (CI) 59%-63%): the estimated prevalence of serum antibody positivity was 72%. Length of injecting, year of commencing drug injecting and the number of times in prison were predictive of antibody positivity. Thirty-one per cent of injectors who commenced their injecting after 1992, following the full establishment of needle/syringe exchange in the city, were salivary antibody positive, and the majority of their infections were acquired outside the prison setting. Respondents who began injecting after the introduction of needle/syringe exchange in the city were significantly less likely to test HCV antibody positive than those who commenced injecting prior to the advent of needle/syringe exchange, after adjusting for length of injecting career.

CONCLUSION: The prevalence of HCV among injectors in Glasgow has decreased during the era of needle/syringe exchange. However, there is evidence to suggest that the incidence of infection remains high. Since the prevalence of hepatitis C viraemia among the city's injecting population is extremely high, ongoing transmission is inevitable unless more effective interventions are identified and implemented urgently.