Abstract

BACKGROUND AND AIMS: While the Netherlands, Canada and Australia were early adopters of harm reduction for people who inject drugs (PWID), their respective HIV and hepatitis C (HCV) epidemics differ. We measured the pooled effect of needle and syringe program (NSP) and opioid agonist therapy (OAT) participation on HIV and HCV incidence in these settings. DESIGN: For each cohort, we emulated the design and statistical analysis of a target trial using observational data. SETTING AND PARTICIPANTS: We included PWID at risk of HIV or HCV infection from the Amsterdam Cohort Studies (ACS, 1985-2013), Vancouver Injection Drug Users Study (VIDUS, 1997-2009), and Melbourne Injecting Drug User Cohort Study (SuperMIX, 2010-2021). MEASUREMENTS: Separately for each infection and cohort (only HCV in SuperMIX), marginal structural models were used to compare the effect of comprehensive (on OAT and 100% NSP coverage, or on OAT only if no recent injection drug use) vs no/partial NSP/OAT (no OAT and/or <100% NSP coverage) participation. Pooled hazard ratios (HR) and 95% confidence intervals (CI) were calculated using random-effects meta-analysis. FINDINGS: We observed 94 HIV seroconversions and 81 HCV seroconversions among 2,023 and 430 participants, respectively. Comprehensive NSP/OAT led to a 41% lower risk of HIV acquisition (pooled HR=0.59, 95%CI=0.36-0.96) and a 76% lower risk of HCV acquisition (pooled HR=0.24, 95%CI=0.11-0.51), compared with no/partial NSP/OAT, with little heterogeneity between studies for both infections (I(2) =0%). CONCLUSIONS: In the Netherlands, Canada and Australia, comprehensive needle and syringe program (NSP) and opioid agonist therapy (OAT) participation appears to substantially reduce HIV and hepatitis C acquisition compared with no or partial NSP/OAT participation. These findings from an emulated trial design reinforce the critical role of comprehensive access to harm reduction in optimizing infection prevention for people who inject drugs.

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