Help me fix: The provision of injection assistance at an unsanctioned overdose prevention site in Toronto, Canada

Background: There is an acute public health crisis from opioid-related poisoning and overdose in Canada. The Moss Park Overdose Prevention Site (MP-OPS) - an unsanctioned overdose prevention site - opened in a downtown park in Toronto in August 2017, when no other supervised consumption services existed in the province. As an unsanctioned site, MP-OPS was not constrained by federal rules prohibiting assisted injection, and provided a unique opportunity to examine assisted injection within a supervised setting. Our objective was to examine the association between assisted injection and overdose, and whether any association between assisted injection and overdose differs according to gender. Methods: Drawing on data from 5657 visits to MP-OPS from October 2017 to March 2018, we used multivariable logistic regression to investigate the relationship between assisted injection and overdose. To examine the influence of gender on this relationship, we further conducted stratified analyses by gender. Results: Among 5657 visits to MP-OPS, 471 (8.3%) received assisted injection, of which 242 (51.4%) were received by women and 226 (48.0%) by men. Using multivariable logistic regression, assisted injection was not associated with overdose in the overall sample (adjusted odds ratio [aOR]1.58, 95% confidence interval [CI]: 0.94, 2.67). In gender-stratified models, women receiving assisted injection were more than twice as likely (aOR 2.23, 95% CI: 1.17, 4.27) to experience overdose than women who did not receive assisted injection, and no association between assisted injection and overdose was found among men. Conclusion: Findings that women receiving assisted injecting are at higher odds of overdose within the supervised setting of the MP-OPS are consistent with previous literature on assisted injection in community settings. Rules banning assisted injection in supervised consumption services may be putting a group of people, particularly women and those injecting fentanyl, at higher risk of health harms by denying them access to a supervised space where prompt overdose response is available.