Background Though known to have abuse potential, benzodiazepine medications remain widely prescribed. Furthermore, issues related to benzodiazepine use by people who inject drugs (PWID) remain to be fully characterized. We therefore sought to examine the prevalence of and risk factors associated with benzodiazepine use in a street-involved urban population. Methods Between May 1996 and November 2013, data were derived from two open prospective cohort studies in Vancouver, Canada, restricted to PWID. Multivariable logistic regression with generalized estimating equations (GEE) was used to determine factors independently associated with benzodiazepine use. Results Over the study period, 2806 individuals were recruited, including 949 (34%) women. Of these, 1080 (38.5%) participants reported benzodiazepine use at least once during the study period. In the multivariable analysis, Caucasian ethnicity, ≥ daily heroin injection, ≥ daily cocaine injection, non-fatal overdose, incarceration, syringe sharing, and unsafe sex were all independently associated with benzodiazepine use. Conversely, older age, homelessness, and ≥ daily crack smoking were negatively associated with benzodiazepine use. Conclusions Use of benzodiazepines was common in this urban setting and was associated with several markers of addiction severity and significant health and social vulnerabilities including syringe sharing and unsafe sex. These findings underscore the need to promote treatment for benzodiazepine use, safer benzodiazepine prescribing, including greater recognition of the limited indications for evidence-based use of this medication class.

Background and Objectives While methadone is well established as an evidence-based treatment for opioid use disorder, safety concerns persist regarding its diversion. We examine the prevalence of and risk factors associated with injection of methadone in an urban population. Methods Between December 2005 and November 2013, data were derived from two open prospective studies of persons who inject drugs (PWID) in Vancouver, Canada. Generalized estimating equations (GEE) logistic regression was used to determine factors independently associated with illicit methadone injecting. Results During the study, 1911 individuals (34% women) were recruited; 134 (7%) participants reported methadone injecting at least once. In multivariable analysis, Caucasian ethnicity [adjusted odds ratio (AOR) = 1.90, 95% confidence interval (CI) = 1.20 – 3.00]; homelessness (AOR = 1.46, 95% CI = 1.09 – 1.95); drug dealing (AOR = 2.10, 95% CI = 1.50 – 2.93); ≥ daily heroin injection (AOR = 1.57, 95% CI = 1.08 – 2.26); ≥ daily crack smoking (AOR = 2.06, 95% CI = 1.44 – 2.95); being a victim of violence (AOR = 1.48, 95% CI = 1.04 – 2.12); and non-fatal overdose (AOR = 1.67, 95% CI = 1.67 (1.00 – 2.79) were independently and positively associated with methadone injection; female gender (AOR = 0.47, 95% CI = 0.30 – 0.75) was negatively associated. Discussion and Conclusion The diversion of methadone for illicit injection in this urban setting was associated with several markers of addiction severity and other health and social vulnerabilities. Scientific Significance These findings underscore the need to ensure methadone accessibility while limiting diversion-related risk.

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