Reduced risk of overdose among clients of a safer opioid supply program in Southwestern Ontario: A pre-post observational cohort study
Abstract
Introduction: North America faces an ongoing overdose crisis driven by a volatile and toxic drug supply comprised primarily of fentanyl, fentanyl analogues and other adulterants. Safer opioid supply (SOS) programs prescribe pharmaceutical opioids to individuals at high risk of overdose mortality. This study evaluated changes in non-fatal overdose prevalence in the 6 months after SOS program initiation among SOS participants in Kitchener-Waterloo, Canada.
Methods: We analyzed data from a pre-post observational cohort of clients enrolled in a SOS program between July 2021 and October 2023. Baseline surveys were completed upon program entry, with follow-up surveys after 6 months. We compared non-fatal overdose prevalence between baseline and follow-up using McNemar’s test and calculated adjusted odds ratios (aOR) using generalized estimating equation (GEE) models, controlling for potential confounders including homelessness, hospitalization, daily fentanyl use, and incarceration.
Results: Among 100 participants completing follow-up (out of 162 who completed a baseline survey), overdose prevalence decreased significantly from 60 % (95 % Confidence Interval (CI): 50–69) at baseline to 15 % (95 % CI: 9–23) at follow-up (p < 0.001). Overdose incidence rates declined from 48.5 to 3.3 per 100 person-months. After adjusting for confounders, participants had 83 % lower odds of overdose during follow-up (aOR 0.17, 95 % CI: 0.08–0.38).
Discussion: Participants in a SOS program experienced significant reductions in non-fatal overdose during the 6 months following program initiation. SOS clients are a high-risk population with elevated overdose rates at baseline; these results support expanding safer supply programs as part of a comprehensive set of strategies to address the overdose crisis.
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