The state of science on including inhalation within supervised consumption services: A scoping review of academic and grey literature.

Background: Internationally, many supervised consumption services (SCS) include drug inhalation (smoking). However, most research is focused on SCS for people who inject drugs. We aimed to: (1) synthesize the literature on including inhalation or other forms of non-injection drug use (e.g., oral, intranasal) within SCS; (2) describe the state of the science on the feasibility of this practice and its outcomes; and (3) outline an agenda for future evaluation research in this area.

Methods: We searched 9 academic and 13 grey literature databases and ultimately included 40 studies. Thirty-two studies (80%) reported findings from feasibility or needs assessments. From these studies, we extracted information on willingness to use these services, perspectives of people who use drugs and other stakeholders, and recommendations for implementation. Eight studies (20%) evaluated including inhalation in SCS, from which we extracted data on associated outcomes. Data were analysed using narrative synthesis and descriptive statistics.

Results: We found high willingness to use SCS including inhalation among people who use drugs, especially those experiencing structural vulnerability. Research emphasized a need for implementation to account for the social nature of drug inhalation, and to limit potential occupational hazards associated with passive inhalation. Positive outcomes associated with inhalation within SCS included improved health and safety of people who use drugs and decreased public drug use. However, this evidence was based primarily on a limited number of studies with designs of mixed quality.

Conclusion: Our review demonstrates feasibility of, and need for, implementing SCS including inhalation, and some potential positive outcomes associated with this practice. However, more comprehensive and systematic evaluations of including inhalation as well as other forms of non-injection drug use (e.g., oral, intranasal, rectal) within SCS should be conducted.