Supervised consumption service use and high-frequency public injecting among people who inject drugs in Toronto: A cross-sectional analysis (2018-2020).

BACKGROUND: Public injecting increases the risk of adverse drug-related outcomes. Supervised consumption services (SCS) have been associated with improvements in individual and public health outcomes. However, evidence of their impact on public injecting within current risk environments remains limited. METHODS: We analyzed cross-sectional survey data from people who inject drugs in Toronto, Canada, between 2018 and 2020. We used modified Poisson regression with robust standard errors to estimate the associations between recent (past 6-month) SCS use and high-frequency public injecting, defined as usually/always versus sometimes/occasionally/never injecting in public, overall and stratified by housing instability. RESULTS: Among 700 participants, 15% (n = 108) reported high-frequency public injecting. In descriptive analyses, compared with infrequent or no public injecting, high-frequency public injecting was associated with younger age (median 36 vs. 40 years), lower educational attainment, housing instability, and needle/syringe sharing; all with 95% CIs excluding the null. Recent SCS use was reported by 87% (n = 608) of participants and was associated with a 51% lower prevalence of high-frequency public injecting (adjusted prevalence ratio (aPR) = 0.49; 95% CI: 0.32-0.77). In analyses stratified by housing instability, this association was observed among participants experiencing mostly unstable housing (aPR = 0.47; 95% CI: 0.29-0.75); among those with some or no unstable housing, precision was limited due to sparse events. CONCLUSION: Recent SCS use was associated with lower prevalence of high-frequency public injecting overall and among individuals experiencing housing instability, underscoring the need for integrated interventions that address housing needs and harm reduction service access.