Safer Opioid Supply Compared With Conventional Opioid Assisted Treatment (Methadone)

"In this population-based study, individuals newly prescribed SOS typically had more comorbidities than people receiving methadone, with higher rates of alcohol use disorder, HIV, hepatitis C, opioid toxicity, infections, and recent engagement in OAT. After matching, we found reduced rates of clinical and health systems outcomes over time among individuals commencing SOS or methadone. In comparative analyses, people receiving SOS had higher rates of opioid toxicities, emergency department visits, inpatient hospitalisations, and incident infections compared with methadone recipients. Although these differences were attenuated after accounting for the high rates of treatment discontinuation during follow-up (which were higher among people who received methadone), rates of opioid toxicities remained higher among people commencing SOS compared with those commencing methadone. Taken together, this study highlights the potential complementary roles of prescribed SOS and methadone as options in response to the urgent drug toxicity crisis, particularly given the higher medical complexity and high rates of recent and concurrent OAT among people receiving SOS.

"Our findings of reduced monthly rates of opioid-related toxicities, health-care use, hospital-treated infections, and non-primary-care-related health-care costs after initiation build upon earlier work showing improved clinical outcomes for people engaged with SOS programmes. Although we observed similar findings in a previous evaluation of a single large SOS programme in London (ON, Canada), that study was not powered to detect changing opioid toxicity rates over time.11 By contrast, we found lower rates of opioid toxicities over time among SOS recipients in this province-wide study. Furthermore, an evaluation of risk mitigation guidance (RMG) prescribing in British Columbia, Canada,15 found significant declines in overdose-related mortality in the week following receipt of an RMG opioid dispensation, with no significant effect on all-cause or overdose-related acute care visits. By contrast, we observed lower rates of acute health service use among people receiving SOS, probably reflecting the longer follow-up observation period in our study. Although our study was not powered to examine death as an outcome, these events were rare, with five or fewer opioid-related deaths among SOS recipients over a 1-year follow-up period.

"A notable difference between our study and previous research is the comparison of outcomes between people commencing SOS and methadone. In between-group comparison, rates of opioid toxicities, all-cause emergency department visits, and hospitalisations were elevated among people newly prescribed SOS relative to individuals commencing methadone. Methadone is typically started at low doses because of the heightened risk of respiratory depression during the first month of therapy, with recent guidelines recommending rapid, safe titration to stable and effective doses for people who use fentanyl.20 Accordingly, short-duration outcomes with methadone reflect a complex mix of patients benefiting from treatment, having early toxicity, and having incompletely treated withdrawal and craving. For these reasons, focusing on 1-year outcomes among new recipients is important to capture the well established benefits of methadone for people retained in treatment.20 Our comparative results also reflect differences in drug-use patterns and the severity of opioid use disorder among SOS recipients that could not be accounted for using administrative health data, and differences in the goals of SOS and OAT programmes.19,21 For example, people receiving SOS had substantially higher rates of medical comorbidities at baseline than individuals commencing methadone, suggesting that SOS use was concentrated among individuals with high acuity and those with serious medical complications from drug use. Importantly, differences between people receiving SOS and those receiving methadone after propensity-score matching suggest that important between-group differences might persist, despite efforts to balance clinical and demographic characteristics and baseline patterns of substance use. Additionally, SOS is a harm reduction measure intended to reduce (but not necessarily eliminate) exposure to the unregulated drug supply for individuals who cannot or choose not to be engaged in OAT or who have tried OAT in the past without success.19,22,23 By contrast, there is variation in clinical approaches to methadone provision, with low-threshold methadone not strictly requiring abstinence from the unregulated drug supply,24 and methadone maintenance programmes typically incorporating more strict requirements for abstinence.25 Therefore, while both SOS and methadone recipients might sometimes access the unregulated drug supply, it is likely that this occurs at higher rates among SOS clients. As a result, we speculate that different patterns of unregulated drug use (eg, frequency of use, injection vs inhalation) and unmeasured differences in severity of opioid use disorder between groups could account, in part, for the higher event rates among SOS recipients."