Background

Mounting evidence suggests that laws and policies prohibiting illegal drug use could have a central role in shaping health outcomes among people who inject drugs (PWID). To date, no systematic review has characterised the influence of laws and legal frameworks prohibiting drug use on HIV prevention and treatment.

Methods

Consistent with PRISMA guidelines, we did a systematic review of peer-reviewed scientific evidence describing the association between criminalisation of drug use and HIV prevention and treatment-related outcomes among PWID. We searched MEDLINE, Embase, SCOPUS, PsycINFO, Sociological Abstracts, CINAHL, Web of Science, and other sources. To be included in our review, a study had to meet the following eligibility criteria: be published in a peer-reviewed journal or presented as a peer-reviewed abstract at a scientific conference; examine, through any study design, the association between an a-priori set of indicators related to the criminalisation of drugs and HIV prevention or treatment among PWID; provide sufficient details on the methods followed to allow critical assessment of quality; be published or presented between Jan 1, 2006, and Dec 31, 2014; and be published in the English language.

Findings

We identified 106 eligible studies comprising 29 longitudinal, 49 cross-sectional, 22 qualitative, two mixed methods, four mathematical modelling studies, and no randomised controlled trials. 120 criminalisation indicators were identified (range 1–3 per study) and 150 HIV indicators were identified (1–5 per study). The most common criminalisation indicators were incarceration (n=38) and street-level policing (n=39), while the most frequent HIV prevention and treatment indicators were syringe sharing (n=35) and prevalence of HIV infection among PWID (n=28). Among the 106 studies included in this review, 85 (80%) suggested that drug criminalisation has a negative effect on HIV prevention and treatment, 10 (9%) suggested no association, five (5%) suggested a beneficial effect, one (1%) suggested both beneficial and negative effects, and five (5%) suggested both null and negative effects.

Interpretation

These data confirm that criminalisation of drug use has a negative effect on HIV prevention and treatment. Our results provide an objective evidence base to support numerous international policy initiatives to reform legal and policy frameworks criminalising drug use.