Assessing the impact of the slow-release oral morphine drug shortages in Ontario, Canada: A population-based time series analysis

•The slow-release oral morphine shortages led to significant treatment disruptions.•People with opioid use disorder experienced sustained periods of discontinuation.•People with pain experienced more temporary periods of discontinuation.•Improved strategies are needed to mitigate harmful impacts of drug shortages Slow-release oral morphine (SROM) is used to manage pain, and as opioid agonist treatment (OAT). Between 2017 and 2021 in Canada, several drug shortages occurred for Kadian© (SROM-24). The purpose of this study was to evaluate the impact of these shortages on people's ability to remain on this medication. We conducted a retrospective population-based time series analysis of SROM-24 dispensed between January 1, 2014, and December 31, 2021, in Ontario, Canada. Using interventional autoregressive integrated moving average models (ARIMA) models, we evaluated the association between SROM-24 drug shortages and treatment discontinuation. Analyses were also stratified by the SROM-24 indication (pain or OAT). We identified 22,479 SROM-24 recipients, of which one-third (33.9%) were aged 65 or above and just over half (51.9%) were female. In our primary analysis of monthly SROM-24 discontinuation, we observed a significant sustained monthly increase following the shortages in November 2019 (+0.29%/month; 95% CI: 0.16%, 0.43%; p