Association between harm reduction intervention uptake and recent hepatitis C infection among people who inject drugs attending sites that provide sterile injecting equipment in Scotland (2012)

Background: Prevalence of the hepatitis C virus (HCV) among people who inject drugs (PWID) in Scotland is high. The Scottish Government has invested significantly in harm reduction interventions with the goal of reducing HCV transmission among PWID. In evaluating the effectiveness of interventions, estimates of HCV incidence are essential.
Methods: During 2008-2009, PWID were recruited from services providing sterile injecting equipment across mainland Scotland, completed an interviewer-administered questionnaire and provided a dried blood spot for anonymous anti-HCV and HCV-RNA testing. Recent infections were defined as anti-HCV negative and HCV-RNA positive. Logistic regression was undertaken to examine associations between recent HCV infection and self-reported uptake of methadone maintenance therapy (MMT) and injection equipment.
Results: Fifty-four percent (1367/2555) of participants were anti-HCV positive. We detected 24 recent HCV infections, yielding incidence rate estimates ranging from 10.8 to 21.9 per 100 person-years. After adjustment for confounders, those with high needle/syringe coverage had reduced odds of recent infection (adjusted odds ratio [AOR] 0.32, 95% CI 0.10-1.00, p = 0.050). In the Greater Glasgow & Clyde region only, we observed a reduced odds of recent infection among those currently receiving MMT, relative to those on MMT in the last six months but not currently (AOR 0.04, 95% CI 0.001-1.07, p = 0.055). The effect of combined uptake of MMT and high needle/syringe coverage was only significant in unadjusted analyses (OR 0.34, 95% CI 0.12-0.97, p = 0.043; AOR 0.48, 95% CI 0.16-1.48, p = 0.203).
Conclusion: We report the first large-scale, national application of a novel method designed to determine incidence of HCV among PWID using a cross-sectional design. Subsequent sweeps of this survey will increase statistical power and allow us to gauge the impact of preventive interventions.