Known fentanyl use among clients of harm reduction sites in British Columbia, Canada.

Background: North America is in the midst of an opioid overdose epidemic and it is commonly suggested that exposure to fentanyl is unknown. Using a provincial survey of harm reduction site clients, we aimed to characterize known and unknown fentanyl use and their correlates among people who use drugs in British Columbia, Canada.

Methods: We recruited 486 clients who were >18 years old and 316 agreed to provide a urine sample for substance use testing. Reported known fentanyl use was defined as a three-level categorical variable assessing recent (i.e., in the previous three days) fentanyl exposure: (i) known exposure; (ii) unknown exposure; and (iii) no exposure. We also assessed any exposure to fentanyl (Yes vs. No) confirmed by urinalysis. Survey data were summarized using descriptive statistics. Multinomial logistic regression and modified Poisson regression models were built to examine different correlates of exposure to fentanyl.

Results: Median age of the participants was 40 (IQR: 32-49). Out of the 303 eligible participants, 38.7% (117) reported known fentanyl use, 21.7% (66) had unknown fentanyl use, and 39.6% (120) had no recent fentanyl use. In the adjusted multinomial logistic regression model and in comparison with unknown fentanyl use, recent known fentanyl use was significantly associated with self-report of methadone use (aRRR = 3.18), heroin/morphine use (aRRR = 4.40), and crystal meth use (aRRR = 2.95). Moreover, any recent exposure to fentanyl (i.e., positive urine test for fentanyl) was significantly associated with living in urban settings (aPR = 1.49), and self-reporting recent cannabis use (aPR = 0.73), crystal meth (aPR = 1.45), and heroin/morphine use (aPR = 2.48).

Conclusion: The landscape of illicit opioid use is changing in BC and more people are using fentanyl knowingly. The increasing prevalence of known fentanyl use is concerning and calls for further investments in public awareness and public policy efforts regarding fentanyl exposure and risks.