Prescribed pharmaceutical alternatives initiative coinciding with reductions in unregulated street opioid use among young people who use drugs: An interrupted time series analysis.

BACKGROUND AND AIMS: In British Columbia, Canada, an initiative was implemented in 2020 to reduce overdose mortality by prescribing pharmaceutical opioids (primarily hydromorphone) as a substitute for the toxic unregulated drug supply. This study estimated changes in the level and trend of unregulated opioid use and non-prescribed hydromorphone use before and after the implementation of prescribed pharmaceutical alternatives (PPA) among a cohort of young people who use drugs.

DESIGN

Longitudinal observational study. Data were drawn from a community-recruited prospective cohort study. We used interrupted time series (ITS) analyses to assess level and trend of self-reported quarterly unregulated opioid and non-prescribed hydromorphone use before, upon and after the implementation of PPA. We used generalized estimating equations (GEE) models to adjust for factors known to influence substance use.

SETTING

Vancouver, British Columbia, Canada, between December 2015 and May 2024.

PARTICIPANTS

644 street-involved young people who use drugs (median age at baseline: 23.4 years; 32.6% women).

MEASUREMENTS: The main outcomes were self-reported any unregulated opioid use and any non-prescribed hydromorphone use in the past six months, obtained through interviewer-administered questionnaires. The primary explanatory variables for the GEE analyses were: time in quarters, interview date after PPA implementation and an interaction term between time and PPA implementation.

FINDINGS: 436 (67.7%) participants reported unregulated opioid use, and 124 (19.3%) reported non-prescribed hydromorphone use during the study. In the ITS analysis, unregulated opioid use showed a statistically significant immediate drop following PPA implementation [per-quarter coefficient (PQC): -5.30; 95% confidence interval (CI) = -10.51 to -0.09], with no statistically significant trend observed in the post-PPA period (PQC: 0.06; 95% CI = -0.35 to 0.47). For non-prescribed hydromorphone use, a downward trend was observed in the pre-PPA period (PQC: -0.46; 95% CI = -0.80 to -0.12). Following PPA implementation, no level change was observed (PQC: 2.61; 95% CI = -2.60 to 7.82), and the pre-existing downward trend was halted (PQC: 0.31; 95% CI = -0.10 to 0.72). The GEE analysis confirmed these opposing trends.

CONCLUSIONS

British Columbia, Canada's 2020 implementation of prescribed pharmaceutical alternatives to reduce opioid overdose mortality was associated with a statistically significant decline in unregulated opioid use and a halt to the pre-existing downward trend in non-prescribed hydromorphone use among a cohort of young people.