5A-03 - Trends in Methadone Prescribing for Opioid Use Disorder between 2015 to 2023: A Population-Based Analysis

Background: The increased potency of the fentanyl-dominated unregulated drug supply has precipitated a shift in patient-reported opioid tolerance and methadone prescribing guidance. However, adoption of new approaches for methadone prescribing remains unknown.

Objectives: We examined methadone initiation trends and impact of changing prescribing guidance on these trends.

Methods: We conducted a population-based repeated time-series analysis among incident methadone recipients in Ontario, Canada between January 2015 and July 2023. We examined monthly rates (per 100,000 Ontario population) of methadone initiated as monotherapy versus in combination with slow-release oral morphine and trends for the maximum methadone dose dispensed on treatment day(s) one, two to seven, and eight to 14. Autoregressive interventional moving average (ARIMA) models were used to examine the impact of new methadone guidance on these trends. Secondary outcomes captured medication use patterns during the two weeks following initiation, including time to first methadone dose increase and maximum change in methadone dose.

Results: We identified 70,564 and 3,069 initiations of methadone monotherapy and combination therapy, respectively. Release of new methadone prescribing guidance was associated with a significant decline in monotherapy initiations (ramp estimate: -0.27 per 100,000; p-value=0.01), and a parallel increase in combination therapy initiations. Starting in 2018, a shift towards attainment of higher doses was noted. This trend was accelerated by release of new guidance, which was associated with decreased initiation at doses < 30mg (ramp estimate: -1.57; p-value=0.02) and increased attainment of 40 to < 50mg (ramp estimate: 0.63; p-value=0.01) and ≥60mg (ramp estimate: 0.71; p-value < 0.01) doses in the first and second week of treatment, respectively. The proportion of monotherapy episodes without a dose increase in the first two weeks rose significantly from 38.5% (initiated before September 2020) to 45.7% afterward. The absolute amount methadone dose was titrated remained generally stable over time.

Conclusions: A shift towards methadone initiation at higher doses and in combination with slow-release oral morphine was noted. However, provision of subsequent rapid dose titration was limited, representing a potential missed opportunity for quicker attainment of therapeutic doses and optimal use of methadone.