Introduction: Needle and syringe programs and opioid agonist therapy are essential for harm reduction among people who inject drugs. Few studies assess their combined potential in preventing hepatitis C virus infection. No studies have assessed whether they perform similarly among individuals at risk of primary and recurrent infection. This study aimed to estimate the rates of hepatitis C virus acquisition according to harm reduction coverage among hepatitis C virus-naive and previously infected people who inject drugs in Montreal, Canada.
Methods: This prospective cohort study involved regular interviews and hepatitis C antibody and RNA testing (data collection: 2010-2017, analysis: 2018). Opioid agonist therapy coverage was defined by current dose: high (≥60 mg/day methadone, ≥16 mg buprenorphine), low, or none. Complete needle and syringe program coverage was defined as exclusively reporting safe needle and syringe sources (past 6 or 3 months). Combined coverage was defined as full (high-dose agonist/complete needle/syringe coverage), minimal (low-dose agonist/incomplete needle/syringe coverage), and partial (remaining combinations). Cox regression models were fit.
Results: A total of 106 events were observed over 1,183.1 person-years for primary and recurrent incidence rates of 10.6 (95% CI=8.0, 13.8) and 7.6 (95% CI=5.6, 9.9) per 100 years, respectively. High-dose opioid agonist therapy was associated with a 77% reduction in hepatitis C virus acquisition (hazard ratio=0.23, 95% CI=0.10, 0.50) compared with not receiving opioid agonist therapy. Needle and syringe coverage was not associated with infection rates. Estimates considering their combination reflected opioid agonist therapy coverage. Associations were similar among hepatitis C virus-naive and previously infected people who inject drugs.
Conclusions: High-dose opioid agonist therapy seems particularly important to reduce drug-related harms among hepatitis C virus-naive and previously infected people who inject drugs in Montreal.
Copyright © 2020. Published by Elsevier Inc.