(139) Trends in opioid toxicities among people with and without opioid use disorder and the impact of the COVID-19 pandemic

Background: Across Canada, the COVID-19 pandemic occurred amidst an ongoing drug toxicity crisis. People diagnosed with opioid use disorder (OUD), are most frequently impacted by harms related to substance use. However, it is currently unknown if the pandemic resulted in disproportionate increases in opioid toxicities among people with OUD compared to those without.

Objectives: To describe trends in opioid toxicities overall and among people with and without OUD and to assess the impact of the COVID-19 pandemic-related state of emergency on event rates.

Methods: We conducted a population-based time series analysis of all opioid toxicities between January 1, 2014, and December 31, 2021, in Ontario, Canada. We used administrative healthcare data housed at ICES, with non-fatal opioid toxicities identified using the National Ambulatory Care Reporting System and Discharge Abstract Database. Fatal opioid toxicities were identified using the Drug and Drug/Alcohol-Related Deaths database. We measured opioid toxicities as a monthly count of all events reported per 100,000 population. Analyses were stratified by people with and without OUD. People with OUD were defined as those who received opioid agonist treatment or an in-hospital OUD diagnosis in the five-years prior to each opioid toxicity. We used interventional autoregressive integrated moving average (ARIMA) models with a ramp function to evaluate the impact of pandemic-related state of emergency (March 2020) on rates of opioid toxicities.

Results: Overall, we identified 80,296 opioid toxicities among 52,052 individuals. Nearly 14% of opioid toxicities were fatal, and 53.5% occurred among people with OUD. We observed a four-fold increase in monthly opioid toxicities between January 2014 (N=356; 2.6 per 100,000 population) and December 2021 (N=1,571; 10.5 per 100,000) which differed among people with OUD (0.8 to 7.4 per 100,000) and without OUD (1.8 to 3.1 per 100,000). Among these individuals, 60.5% were male, and 46.2% were 25-44 years old. We observed a significant ramp increase in the overall rate of opioid toxicities following the declaration of a pandemic emergency [0.2 per 100,000 monthly (~30/month), 95% CI: 0.029, 0.36, p=0.02]. We found a similar ramp increase among people with OUD (0.2 per 100,000 monthly, 95% CI: 0.10, 0.28, p <.001), however this was non-significant among people without OUD (p=0.95).

Conclusions: The rate of opioid toxicities has continued to grow across Ontario, with a substantial prolonged acceleration during COVID-19. The important differences observed among people with OUD compared to those without, highlights the critical need for improved access to harm reduction programs and the continued monitoring of opioid-related harms post-pandemic.