(B-160) Patient and Prescriber-related factors associated with return to daily-dispense methadone: A multilevel cohort study

Background: After the SARS-CoV-2 emergency declaration, modified opioid use disorder guidance recommended take-home methadone doses for those previously ineligible to promote treatment retention. However, a majority of these individuals were subsequently reverted to daily dispensed methadone. Factors associated with return to daily-dispensed methadone remain unknown.

Objectives: To identify person and prescriber related factors associated with the return to daily dispensed methadone among Ontario, Canada residents actively receiving daily dispensed methadone on March 21, 2020, and subsequently provided at least one take-home dose between March 22, 2020, to April 21, 2020.

Methods: We followed individuals from their first take-home dose until they returned to daily dispensed methadone or met censoring criteria. Follow-up time was divided into 14-day discrete time intervals. The primary outcome was the return to daily dispensed methadone, defined as the first interval where a take-home dose was not dispensed. We measured baseline and time-varying characteristics at the patient (e.g., demographic and clinical history) and prescriber (e.g., clinical practice patterns) level. We used a multilevel discrete time survival model with a complementary log-log link function and random intercepts across prescribers to approximate a proportional hazards frailty model and account for patient clustering by prescribers.

Results: We identified 2,863 individuals in our study cohort, of which 63.8% were male and 48.0% were prescribed their initial take-home dose by a high-volume opioid agonist therapy prescriber. Within 26 weeks, 1,675 (58.5%) individuals were reverted to daily dispensed methadone. Person-level variables significantly associated with our primary outcome include occurrence of an emergency department visit during or before the interval of interest (HR=1.27; 95% CI=1.05, 1.55) and missed methadone dose(s) in the interval prior (HR=1.59; 95% CI=1.44, 1.76). Although those dispensed doses ≥ 120mg at index initially had a lower hazard of return to daily dispensed methadone compared to those dispensed doses ≤60mg (HR=0.71; 95% CI=0.52, 0.97), this relationship dissipated over time (HR=1.07; 95% CI=1.02, 1.13). Lastly, patients prescribed methadone by a high volume (top 10th percentile) opioid agonist treatment prescriber had an increased hazard of return to daily dispensed methadone compared to those prescribed methadone by a low volume (50th percentile) prescribers (HR=1.44; 95% CI=1.14, 1.83).

Conclusions: While patient related clinical indicators for return to daily dispensed methadone were identified, prescriber practice patterns may influence their decision to revert patients to daily dispensed methadone.