One-third of opioid-related deaths in Ontario were among people actively being treated with prescription opioids in 2016. However, this proportion has decreased significantly since 2013, according to a new study by researchers at the Institute for Clinical Evaluative Sciences (ICES), St. Michael’s Hospital, and the Ontario Drug Policy Research Network (ODPRN).

“This study highlights the important role of prescribed, diverted, and illicit opioids to fatal overdoses across the province. Although, in 2016, the majority of opioid-related deaths occurred among people not currently being prescribed these medications from a physician, prescription opioids continue to contribute to opioid-related deaths. For example, among people not actively being prescribed opioids at their time of death, oxycodone, hydromorphone, methadone and morphine were frequently involved in the overdose, implying that these deaths likely involved diverted prescription opioids,” says Dr. Tara Gomes, a scientist at ICES and the Li Ka Shing Knowledge Institute of St. Michael’s Hospital and a principal investigator of ODPRN.

Although the role of prescription opioids in opioid-related deaths has decreased since 2013, prescribed, diverted (legally prescribed opioids that have been transferred from the person with the prescription to another person for illicit use), and illicit opioids all played an important role in opioid-related deaths in 2016. Of the 2,833 opioid-related deaths identified, an active opioid prescription on the date of death was relatively common, but declined slightly throughout the study period (38.2% in 2013 vs 32.5% in 2016).

“We found a concerning trend of increased non-prescribed fentanyl involvement in 2016, which aligns with the recent introduction of illicit fentanyl to the market. Nearly half of opioid-related deaths among people with no active prescriptions involved fentanyl in 2016, and it is anticipated that this has continued to rise in more recent years,” says Dr. Gomes.

Older individuals and women were relatively more likely to have an active opioid prescription at time of death. In 2016, 46.4% of those aged 45 to 64 had an active opioid prescription compared with only 11.6% among those aged 24 or younger. Similarly, 45.6% of women had an active opioid prescription at time of death compared to 26.4% of men.

“It is important to be aware of the complex opioid environment that currently exists in Ontario, where illicit opioids, as well as prescription opioids that are either prescribed or diverted, are playing an important role in opioid-related deaths. Approaches designed to address this issue must consider all of these factors, as well as the inter-relationship between the prescribed and illicit market. For example clinicians who rapidly taper opioid doses in their patients can force a transition to sourcing opioids from illicit sources, which is inherently less safe,” says Dr. Gomes.

The study “Contributions of prescribed and non-prescribed opioids to opioid-related deaths: A population-based cohort study in Ontario, Canada,” was published today in the BMJ.