Comparing the effects of prescribed safer opioid supply and methadone in Ontario, Canada: a population-based matched cohort study

Abstract

Background: Prescribed safer opioid supply (SOS) programmes are novel harm reduction interventions. We examined health outcomes among people receiving SOS over time and relative to a similar group of people receiving methadone.

Methods: We conducted a population-based cohort study among new SOS and methadone recipients in Ontario, Canada, who commenced treatment between Jan 1, 2016 and Dec 31, 2021. People receiving SOS were matched (1:1) to new methadone recipients based on age (within 3 years), sex, location of residence (public health unit), and propensity score (within 0·2 SDs). Primary outcomes were hospital-treated opioid-related toxicities, emergency department visits and inpatient hospitalisations, incident infections, and health-care costs (in CA$, excluding costs related to primary care services and medications) over 1 year of follow-up. Outcome rates were calculated over the follow-up period, with censoring on death, discontinuation of SOS or methadone, or end of follow-up (360 days). Within-group changes in outcomes were assessed using interrupted time-series analysis, and Prentice-Williams-Peterson regression was used to assess between-group differences in recurrent events.

Findings: Of the 991 new recipients prescribed SOS and 25 116 new methadone recipients who met the eligibility criteria, 856 (86·4%) people receiving SOS were matched to 856 people receiving methadone. In the within-group analysis, matched SOS recipients had significant improvements in the monthly rate of opioid toxicities (step change -1·09 events per 100 individuals [95% CI -2·12 to -0·07]; p=0·037), all-cause emergency department visits (-8·85 per person-year [-13·5 to -4·20]; p=0·0002), all-cause inpatient hospitalisations (-2·08 per person-year [-3·41 to -0·75]; p=0·0022), incident infections (-0·68 per person-year [-1·22 to -0·14]; p=0·013), and non-primary-care-related health-care costs (-$91 699 per person-year [-112 749 to -70 650]; p<0·0001). Results were consistent for methadone recipients. In the between-group analysis, individuals commencing SOS had significantly higher hazards of opioid toxicity (hazard ratio 2·83 [95% CI 1·97 to 4·06]), emergency department visits (1·16 [1·05 to 1·29]), and inpatient admissions (1·50 [1·13 to 1·99]), no significant difference in the rate of incident infection (1·51 [0·87 to 2·61]), and were less likely to discontinue treatment than those commencing methadone (0·62 [0·55 to 0·70]). When treatment discontinuation was removed as a censoring criterion, we found no difference between groups in the hazard of any of the primary outcomes except opioid toxicity (1·65 [1·38 to 1·97]).

Interpretation: SOS and methadone were associated with improvements in health outcomes, including reduced opioid toxicities and health-care use, in the year after treatment initiation. The findings suggest SOS programmes play an important, complementary role to traditional opioid agonist treatment in expanding the options available to support people who use drugs.

Funding: Canadian Institutes of Health Research and Ontario SPOR Support Unit.