What is the ideal time to begin tapering opioid agonist treatment? A protocol for a retrospective population-based comparative effectiveness study in British Columbia, Canada.

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 to local advocacy groups and decision-makers, national and international clinical guideline developers, presented at international conferences and published in peer-reviewed journals electronically and in print.