Drug poisoning, caused predominantly by fentanyl in the unregulated drug supply, is the leading cause of death among persons 10–59 years in British Columbia (BC), Canada. In March 2020, in response to the emergence of the COVID-19 pandemic, the province of BC released the Risk Mitigation Guidance (RMG) as a clinical tool for physicians and nurse practitioners, allowing prescribers to provide selective withdrawal management medications, such as hydromorphone, dextroamphetamine, diazepam and others, as a legal and regulated supply of pharmaceutical alternatives to individuals who were at-risk of COVID-19 and overdose. In July 2021, the government of BC released the prescribed safer supply (PSS) policy, extending the scope beyond the COVID-19 pandemic and initial medications offered under the RMG. Recent studies have shown clear benefits among people with a diagnosed opioid use disorder who were prescribed PSS, in reducing mortality, as well as improving retention on opioid agonist treatment for those who were coprescribed PSS medications. The objective of the analysis detailed in this protocol is to use a cross-model comparison approach, comparing two independently developed models which are currently used in public health institutions in BC, to estimate the impact of this policy on opioid overdose-related mortality, while also considering the potential negative impacts of PSS medication diversion to those who are opioid naïve. This project will add to the limited evidence-base on the population-level impact of pharmaceutical alternatives interventions to date.

We have identified two appropriate mathematical models to evaluate the impact of PSS on the number of opioid overdose-related deaths within BC from the inception of the programme (March 2020) until December 2022. We will use recently established guidelines on conducting a cross-model comparison to identify structural and parameter differences between the models and perform adaptation steps to generate the counterfactual scenarios. These will include creating additional health states for the population representing individuals receiving PSS, and parameterising the overdose risk, mortality and retention in the new compartments from a comprehensive population-level data set. Harmonisation will be conducted to ensure that both models evaluate the same scenarios with the same data. Further sensitivity analyses will be conducted to consider alternative counterfactual scenarios and changes to the population following the implementation of the intervention.

This study is exempt from research ethics board review, as outlined in the Tri-Council Policy Statement, because it relies on data that is available in the public domain and there is no possibility of identifying individual persons. Results of the model validation analysis will be distributed through peer-reviewed journals and knowledge translation materials posted on the websites of the BC Centre for Disease Control and Centre for Advancing Health Outcomes.

https://osf.io/kju2p/overview.

The introduction of fentanyl and its analogues in the illicit drug supply has prompted greater emphasis on refining clinical treatment protocols to ensure sustained retention in opioid agonist treatment (OAT). Take-home dosing may lessen the treatment burden on clients and thus reduce the risk of treatment discontinuation. The evidence base supporting the use of take-home dosing, including the optimal duration of dispensations, is, however, limited. The objective of this study is to determine the comparative effectiveness of alternative take-home dosing schedules, as observed in clinical practice in British Columbia, Canada from 2010 to 2022.

We propose to emulate a target trial with a population-level retrospective study of individuals initiating methadone or buprenorphine/naloxone between 1 January 2010 and 31 December 2022 who are 18 years of age or older and not currently incarcerated or pregnant with no history of cancer or palliative care. Our study will draw on nine linked health administrative databases from British Columbia and will evaluate take-home doses of 2–5 days, 6 days or >6 days compared with continuous daily dosing. The primary outcomes include OAT discontinuation and all-cause mortality on treatment. A causal per-protocol analysis is proposed with longitudinal matching and inverse probability of censoring weighting approaches to adjust for time-fixed and time-varying confounding. A range of sensitivity analyses will be executed to determine the robustness of results.

The protocol, cohort creation and analysis plan have been classified and approved as a quality improvement initiative by Providence Health Care Research Ethics Board and the Simon Fraser University Office of Research Ethics. Results will be disseminated and shared with local advocacy groups and decision-makers, developers of national and international clinical guidelines, presented at national and international conferences and published in peer-reviewed journals electronically and in print.

Opioid use disorder (OUD) during pregnancy is associated with increased rates of adverse perinatal, foetal and neonatal health events. Opioid agonist treatment (OAT) can substantially reduce the risk of these potential harms. In British Columbia (BC), methadone and buprenorphine/naloxone are first-line treatment options for pregnant people with OUD. However, the comparative effectiveness of these regimens during pregnancy remains poorly understood, particularly in terms of how dosage may impact clinical outcomes. This protocol outlines a proposed population-based retrospective study to evaluate the comparative effectiveness of methadone compared with buprenorphine/naloxone during pregnancy on perinatal and neonatal health outcomes.

We propose to conduct a retrospective observational study using population-based data from individuals who received methadone or buprenorphine/naloxone during pregnancy between 1 April 2010 and 31 March 2022. Data will be collected from 10 linked population-level administrative databases. We will emulate target trials using intention-to-treat and per-protocol approaches. We will use a pooled logistic regression approach to assess the impact of methadone versus buprenorphine/naloxone on time to OAT episode discontinuation and a dose-response marginal structural model to evaluate neonatal health at delivery. An exploratory observational analysis will also be conducted to describe the impact of methadone vs buprenorphine exposure during the first trimester of pregnancy on congenital malformations and anomalies.

This study has been determined to meet the criteria for exemption per Article 2.5 of the 2018 Tri-Council Policy Statement: Ethical Conduct for Research Involving Humans. Study databases have been made available by the BC Ministries of Health and Mental Health and Addiction as part of the provincial opioid overdose public health emergency response. Results will be disseminated to policymakers, clinical partners, community programmes and people with lived and living experience of substance use and published in peer-reviewed journals.