Background and aims: Prescription opioid injection (POI) is a leading risk factor for hepatitis C virus (HCV). Residential context relates to high-risk injection behaviour. This study assessed whether residence in the inner city (versus surrounding areas in Montréal Island) modified the effects of correlates of POI or the relationship between POI and HCV incidence. Design: Prospective cohort study. Setting: Montréal, Canada. Participants: A total of 854 people who inject drugs (18% female, 25% age < 30 years), living on Montréal Island, were interviewed every 3–6 months from 2004 to 2012. Measurements Study visits included HCV antibody testing and an interviewer-administered questionnaire. Generalized estimating equations were used to test whether place of residence modified the effects of correlates of POI. Cox regression was used to test whether place of residence modified the relationship between POI and HCV incidence. Findings: At baseline, inner-city participants were more likely to report POI in the past month (40 versus 25%, P < 0.001). The association between POI and heroin injection, syringe sharing and sharing of injecting equipment varied according to place of residence and was greater in the inner city. The hazard of HCV infection associated with POI was greater among inner-city participants compared to those in the surrounding areas [adjusted hazard ratio (HR) = 3.38, 95% confidence interval (CI) = 1.88–6.07 versus HR = 1.26, 95% CI = 0.65–2.42, P = 0.025]. Conclusions: Among people who inject prescription opioids in Montréal, Canada, those who live in inner-city areas are more likely to engage in injecting-related risk behaviours and have a higher risk of hepatitis C virus infection than those who live in the suburbs.
- Cohort study
- Geographic Information Systems
- hepatitis C
- injection drug use
- prescription opioids