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Abstract

Introduction: The proliferation of fentanyl and its analogues in illegal, unregulated drug markets remains a major driver of the overdose crisis in North America. Drug checking services have been implemented as a harm reduction strategy to address the crisis. However, little is known about their potential utility as a mechanism for monitoring population-level risk of overdose stemming from changing fentanyl concentration in unregulated drugs over time. Therefore, the present study assessed the relationship between median fentanyl concentration in expected opioid drug checking samples and the illicit drug toxicity death rate over time in Vancouver, Canada. Methods: Monthly population-based illicit drug toxicity death rates were drawn from provincial coroner records. Monthly median percent fentanyl concentration was calculated using a validated quantification model from point-of-care Fourier-Transform Infrared (FTIR) spectra among expected opioid samples that tested positive for fentanyl at community drug checking services. A time series analysis using generalized additive modelling was conducted to examine the association between monthly median fentanyl concentration and monthly illicit drug toxicity death rate, controlling for calendar month. Analyses were conducted in 2021-2022. Results: Between January 2019 and October 2020, 577 illicit drug toxicity deaths occurred in Vancouver, and the observed monthly rate ranged from 1.75 to 7.65 deaths per 100,000 population. A significant, positive association was observed between monthly median fentanyl concentration and monthly illicit drug toxicity death rate, adjusting for calendar month (χ2=52.21, p<0.001). Conclusions: Findings suggest a role for point-of-care drug checking as a tool for monitoring evolving overdose risk at the population level.