Patterns of opioid toxicity deaths after the implementation of COVID-19 emergency measures in Ontario, Canada: a weekly interrupted time series

Abstract

Background

In March 2020, Ontario, Canada, implemented COVID-19 public health measures, including school and non-essential business closures, physical distancing, border restrictions, and modified health services. We examined their association with changes in opioid toxicity mortality and assessed variations across age, sex, health region, and drug type.

Methods

We conducted an interrupted time series using opioid toxicity death records (March 2019 to February 2021) from the Office of the Chief Coroner for Ontario. Using a generalized linear model (Poisson or negative binomial), we estimated changes in weekly death counts following the first (March 17th to May 19th, 2020) and second (November 23rd, 2020, to February 14th, 2021) lockdowns, as well as the entire post-COVID-19 period, modelling interventions as level shifts in opioid toxicity deaths.

Results

Of 3844 individuals who died within the study period, 74.4 % were male, and the median age was 40 (interquartile range: 31 to 51). Weekly deaths ranged from 9 to 72. Following the province-wide state of emergency and first lockdown, there was a step increase in the number of deaths, with an estimated Rate Ratio (RR) of 1.21 (95 % CI 1.02 to 1.52). Over the duration of the post-COVID-19 period, an overall sustained increase in the number of opioid toxicity deaths (RR 1.11 [95 % CI 1.02 to 1.41]) was observed across the province.

Implications

The period after initial COVID-19 measures was associated with increases in opioid toxicity mortality. Future responses to public health emergencies must proactively mitigate the potential unintended consequence of toxic drug-related harms among substance-using populations.