Evaluating Buprenorphine/Naloxone Microdosing vs. Standard Dosing in Emergency Departments

This multi-centered, open-label RCT will be carried out at four emergency departments (EDs) across Canada, two in British Columbia (Vancouver General Hospital and St. Paul's Hospital) and two in Alberta (Royal Alexandra Hospital and Northeast Health Centre). The investigators will randomize the selected patients to receive take-home microdosing or standard dosing packages. These will include a five-day regimen in a bubble package, along with over-the-counter adjunctive medication. The details of the different regimens are outlined in the "Study Arms" section of this page, and the adjunctive medication regimen is highlighted below.

The primary objective of the current study is to compare the effectiveness of ED-initiated buprenorphine/naloxone take-home standard dosing and microdosing interventions for patients with opioid use disorder identified at the four study ED's, with regard to a) successful completion of the induction period (primary outcome) and b) retention on opioid agonist therapy at 30, 90, and 365 days following ED visit, or decreasing overdose, mortality and healthcare utilization (secondary outcomes).

The primary outcome measure will be whether the patient filled a prescription for buprenorphine/naloxone within two weeks of their ED visit (binary variable). If this occurs, the investigators presume that the patient successfully completed the induction regimen provided, followed up with a healthcare provider able to prescribe buprenorphine/naloxone, and was subsequently prescribed ongoing buprenorphine/naloxone therapy. The investigators chose a two-week period, recognizing that patients receiving take-home packages from the ED may not start taking the induction regimen immediately after the ED visit, but instead may decide to delay the start of their regimen to a time that is more convenient to them. The investigators hypothesize that most patients would decide to start within two weeks of their ED visit. This hypothesis is supported by peer advisors on the study team.

Secondary outcomes will include retention on OAT, which will be assessed using provincial pharmacy records (PharmaNet and PIN) up to 30, 90 and 365 days.

The investigators will also examine fatal or non-fatal overdose, mortality, ED visits, physician visits, admissions, and days admitted within 30, 90 and 365 days (timeframes plausibly attributable to ED interventions). The investigators expect that successful OAT initiation would lead to decreased healthcare use, consistent with our previous work indicating high admissions among persons with recent OUD diagnoses and OAT discontinuation. The investigators will also assess patients' self-reported experiences with study regimens, withdrawal, precipitated withdrawal, and comfort via participant surveys.

The study will offer co-interventions to both the intervention and control groups that will be outlined in study-related pre-printed clinical ordersets. This will include symptomatic treatment of nausea/vomiting (dimenhydrinate: 50 mg PO q6h prn - 6 doses), and pain or myalgias (acetaminophen: 975 mg po q6h prn - 6 doses) (ibuprofen: 400 mg po q6h prn - 6 doses), to use in the first two days of inductions, when the investigators expect withdrawal symptoms to be most challenging, especially for standard dosing. Those receiving microdosing may experience breakthrough withdrawal if they do not take an adequate dose of overlapping opioid. Of note, enrolled patients will also be offered counselling with ED social workers to aid with social or other patient needs (e.g., housing, transportation).

This RCT builds on interventions, recruitment, and follow-up procedures successfully tested in a feasibility study. The study team has expertise in emergency and addictions medicine, peer engagement, community overdose prevention, biostatistics, health economics, and RCT implementation, including the high-profile SALOME trial comparing heroin and hydromorphone treatments in our target population. Knowledge users from provincial health ministry and regions will ensure scale-up. The study team are engaging people with lived experience throughout study design, implementation, and interpretation to ensure relevance.

The investigators will ascertain our primary and secondary outcome measures relating to completion of induction and retention on OAT, on records of prescriptions filled in provincial pharmacy databases: PharmaNet in BC, and the Pharmaceutical Information Network in Alberta. The investigators specifically selected partner sites in BC and Alberta to allow our team to access these provincial administrative databases for outcome ascertainment, which will minimize losses to follow-up and strengthen the reliability of our results. The investigators will assess secondary outcomes of overdose and mortality by linking our study cohort to the BC Centre for Disease Control Overdose Cohort (for patients enrolled in BC), and to provincial Vital Statistics data (Alberta and BC). The investigators will assess secondary outcomes related to healthcare utilization by linking our study cohort to provincial databases on emergency department visits (National Ambulatory Care Reporting System) and hospitalizations (Discharge Abstract Data) in Alberta and BC. We will access all administrative databases through Population Data BC (PopData BC) and Alberta Health Services.

This trial will inform urgent development of effective ED buprenorphine/naloxone programs to improve OAT access for people at high risk of overdose. The investigators will leverage our networks of policy makers, public health leaders, and health providers to enable rapid dissemination of findings in guidelines and policies across Canada.

• Number of patients retained in Opioid agonist therapy (OAT) following the ED visit [Срок оценки: 30, 90, and 365 days]
• Number of fatal or non-fatal overdose events, mortality, ED visits, physician visits, admissions, and days admitted to hospital for patients following ED visit. [Срок оценки: 30, 90, and 365 days.]