Table 2. Association of Opioid RMG Receipt With OAT Receipt Using High-Dimensional Propensity Score–Matched Cohorts.
| Analysis | No. of individualsb | Adjusted risk ratio (95% CI) for RMG vs no RMGa | |
|---|---|---|---|
| RMG 1-3 d | RMG ≥4 d | ||
| Primary analysis | 4633 | 1.27 (1.25-1.30) | 1.46 (1.43-1.49) |
| Subgroup analysesc | |||
| People initiating OAT and opioid RMG concurrently | 2352 | 1.56 (1.50-1.62) | 2.04 (1.97-2.11) |
| During OAT induction (up to 4 weeks) | 2352 | 1.06 (1.03-1.09) | 1.42 (1.38-1.45) |
| People initiating OAT before opioid RMG initiation | 2281 | 1.07 (1.05-1.09) | 1.15 (1.12-1.17) |
| People initiating or receiving methadone | 2859 | 1.22 (1.19-1.25) | 1.40 (1.37-1.43) |
| People initiating or receiving buprenorphine-naloxone | 427 | 1.34 (1.18-1.53) | 1.56 (1.40-1.73) |
| People initiating or receiving other forms of OAT | 1348 | 1.27 (1.21-1.32) | 1.49 (1.44-1.54) |
Abbreviations: OAT, opioid agonist treatment; RMG, risk mitigation guidance.
The RMG prescriptions included hydromorphone tablets or sustained-release oral morphine.
Number of individuals receiving RMG, matched with unexposed group. The marginal structural model with inverse probability of treatment weights controlled for age; sex; rurality of residence; service access (Vancouver or South/Central Vancouver Island vs others); income assistance receipt in the past 12 months; prior-week OAT dispensation (none, suboptimal, or optimal); unstable housing in the past 2 months; years since the first opioid use disorder indication (<5, 5-9, or ≥10); overdose-related acute care visits in the past 30 days; Charlson Comorbidity Index (>0); Chronic Disease Score; any prior indication of disorder for substance use, alcohol use, mental health, HIV, hepatitis C virus, or chronic pain in the past 12 months; tobacco use in the past 12 months; any cancer or palliative care in the past 12 months; incarcerated in the past 12 months; physician attachment in the past 12 months; opioid dispensation other than OAT prescription in the past 60 days; benzodiazepine dispensation in the past 60 days; week of follow-up (linear and quadratic); and calendar month of time zero from 1 (March to April 2020) to 17 (August 2021) (linear and quadratic).
On the basis of RMG initiation week for the exposure group and the matched unexposed group.