Evaluating the Evidence Base for Supervised Drug Consumption Services: A Systematic Review of Methodological Quality, Causal Inference, and Evidence Strength
Year: 2026
Type: study-registration
Abstract: Supervised drug consumption services (SDC) - also referred to as supervised injection facilities, supervised injection services, drug consumption rooms, and overdose prevention sites—are legally sanctioned settings where people who use drugs can consume pre-obtained substances under staff supervision. These services may provide sterile consumption equipment, emergency overdose response, drug checking, and connections to health and social supports. SDC have been implemented in multiple countries as part of harm-reduction responses to overdose, infectious disease transmission, and other substance-related harms. A substantial literature has evaluated the effectiveness and safety of SDC, including associations with overdose mortality, high-risk consumption behaviors, treatment and health-care engagement, public order, and stigma. However, existing reviews have largely focused on synthesizing reported outcomes, with comparatively limited systematic assessment of the methodological quality, risk of bias, and capacity for causal inference of the underlying primary studies. This distinction is important because conclusions intended to inform public-health policy depend not only on the direction and consistency of findings, but also on the rigor of the study designs and analytic methods that produced them. This systematic review will evaluate the methodological quality and evidentiary strength of peer-reviewed original research on SDC published from 1986, when the first SDC opened, through October 2026. The primary research question is: What proportion of the SDC evidence base comprises study designs and methodological rigor capable of supporting causal inference and robust conclusions about SDC effects? Eligible studies will examine supervised consumption facilities or services, including overdose prevention sites, among people who use substances, without restrictions on age, gender, or route of substance use. Quantitative, qualitative, and economic evaluation studies will be eligible. Studies may report any health, behavioural, service-use, community-level, economic, or implementation outcome. Studies involving incarcerated populations; interventions without supervised consumption; studies conducted in low- and middle-income countries; non-peer-reviewed literature; reviews; editorials; commentaries; and studies without English- or French-language full text will be excluded. We will search MEDLINE, Embase, APA PsycINFO, Web of Science, and ScienceDirect, supplemented by backward and forward citation tracking. Two reviewers will independently screen records, extract data, and assess methodological quality. Extracted variables will include study characteristics, research focus, outcomes, population characteristics, geographic setting, study design, comparator type, follow-up, recruitment, statistical methods, and indicators of causal inference. Quantitative studies will be appraised using the MASTER (Methods, Analysis, Safeguards, Transparency, Evidence, Reporting) Checklist. Economic evaluations will additionally be assessed using the CHEERS checklist. Study findings will be classified according to their suitability for causal inference - high, moderate, or low - by integrating methodological safeguards with evidence of temporal ordering, empirical association, and control of confounding or other sources of spurious association. The review will summarize these classifications descriptively and examine how methodological rigor and causal-inference suitability vary across study designs, outcome domains, populations, geographic regions, and time periods. Meta-analysis of intervention effects is not a primary objective, but may be considered for sufficiently homogeneous subgroups.
Source: Open Science Framework
Authors: Nathaniel Day, Daniel Devoe, Vanja Grubac
Language: English
Topic: HIV, Drug Use, Sexual Risk
Subfield: Epidemiology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7212438792