BACKGROUND

Long-term prescription opioid use has been associated with adverse health outcomes, including opioid use disorder (OUD). We examined a population of opioid naïve individuals who initiated prescription opioids for non-cancer pain and investigated the associations between opioid prescription characteristics at initiation and time to treated OUD.

METHODS

We conducted a retrospective population-based cohort study in Ontario, Canada among opioid naïve individuals aged 15 years and older dispensed an opioid for non-cancer pain between 2013 and 2016. We used the Narcotic Monitoring System to abstract opioid dispensing data. A multivariable Cox regression model was used to examine the association between average daily dose and time to treated OUD.

RESULTS

We identified 1,607,659 opioid-naïve individuals who initiated a prescription opioid within the study period. The incidence of treated OUD within the study period was 86 cases per 100,000 person-years. Compared to an average daily dose of <20 morphine milligrams equivalent (MME), higher average daily doses at initiation were associated with greater hazard of treated OUD, 20-50 MME (HR 1.11, 95% CI: 1.02, 1.21), >50-90 MME (HR 1.29, 95% CI: 1.16, 1.44), >90-150 MME (HR 1.29, 95% CI: 1.06, 1.56), >150-200 MME (HR 2.49, 95% CI: 1.54, 4.03) and >200 MME (HR 4.15, 95% CI: 2.89, 5.97). Long-acting formulations and days' supply ≥11 days were also associated with greater hazard of treated OUD.

CONCLUSION

Prescription opioid characteristics at initiation are associated with risk of treated OUD, identifying potentially important and modifiable risk factors among people initiating opioids for non-cancer pain.