Characterizing opioid agonist treatment discontinuation trends in British Columbia, Canada, 2012-2018

Given the elevated risk of mortality immediately following opioid agonist treatment (OAT) discontinuation, determining the frequency and timing of OAT discontinuation can help guide the planning of services to facilitate uninterrupted OAT. We sought to describe weekly and monthly trends in OAT episode discontinuations in British Columbia to determine the potential resource needs for implementing support services.

This population-based retrospective study utilized a provincial-level linkage of health administrative databases to identify all people with opioid use disorder (PWOUD) who received OAT between 01/2012-08/2018. We defined OAT episodes as continuous medication dispensations without interruptions in prescribed doses lasting ≥5 days for methadone and ≥6 days for buprenorphine/naloxone. We derived the percentage of PWOUD discontinuing OAT every month and we considered weekly discontinuations between 09/2017-08/2018, accounting for weeks during which monthly income assistance payments from social service programs occurred.

Our study included 37,207 PWOUD discontinuing 158,027 OAT episodes. Discontinuations were relatively stable month-to-month, increasing from 10.6 % to 14.9 % (2012-2018). The monthly percentage of discontinuations was 21.2 % for buprenorphine/naloxone and 10.0 % for methadone. Weekly discontinuations were greater in income disbursement weeks (816; IQR: 752, 901) compared to other weeks (655; IQR: 615, 683; p < 0.01).

We identified a high, and stable rate of monthly OAT discontinuations and a consistently higher rate of discontinuing treatment among PWOUD accessing buprenorphine/naloxone. There is an urgent need to develop the evidence base for interventions to support OAT engagement and to improve clinical management of OUD to address the opioid-related overdose crisis.