What impact did the COVID-19 pandemic have on the variability of fentanyl concentrations in the Vancouver, Canada illicit drug supply? An interrupted time-series analysis.

BACKGROUND

Increases in fatal overdoses were observed coinciding with the COVID-19 pandemic across the USA and Canada. Hypothesised explanations include pandemic-attributable healthcare service disruption, social isolation and illicit drug market disruption. Using data from a community drug checking service, this study sought to evaluate how COVID-19 pandemic measures affected the variability in fentanyl concentrations within the local illicit drug market.

METHODS

Using a validated quantification model for fentanyl, Fourier-transform infrared spectra from fentanyl-positive drug checking samples in Vancouver, Canada were analysed to determine fentanyl concentration. An interrupted time-series analysis using an ordinary least squares model with autoregressive adjusted SEs was conducted to measure how the variance in monthly fentanyl concentrations changed following the declaration of the COVID-19 public health emergency in March 2020.

RESULTS

Over the study period, 4713 fentanyl-positive samples were available for analysis. Monthly variance of fentanyl concentrations ranged from 7.9% in December 2017 to 159.2% in September 2020. An interrupted time-series analysis of variance in fentanyl concentrations increased significantly following the declaration of the COVID-19 public health emergency, with an immediate level change of 26.1 (95% CI 7.2 to 45.0, p=0.011) and a slope change of 15.8 (95% CI 10.2 to 21.4, p<0.001).

CONCLUSION

Though community drug checking samples may not be generalisable to the wider illicit drug market, our study found that variance in fentanyl concentrations increased significantly following the declaration of the COVID-19 public health emergency. While it remains unclear whether the observed increase in the variability of fentanyl concentration in illicit opioids was a direct result of COVID-19 and related measures, the volatility of fentanyl concentrations is likely to have posed significant risk to people who used drugs in this setting.