Opioid agonist treatment dispensing trends between 2018 and 2022 across six Canadian provinces.

Opioid agonist treatment (OAT) is the recommended first-line therapy for individuals with opioid use disorder. The availability of different products and prescribing guidance for OAT has rapidly evolved in recent years. Therefore, we conducted a repeated cross-sectional study using pharmacy dispensing data from six Canadian provinces to examine trends in methadone and buprenorphine use between January 2018 and December 2022. Monthly population-adjusted rates of OAT recipients were calculated by province, and annual cohorts were stratified by demographic characteristics and OAT type. Prevalence of OAT use varied across provinces, ranging from 1.03 per 1000 in Quebec to 3.59 per 1000 in British Columbia. Increases in OAT use between 2018 and 2022 were observed in Alberta (3.00-3.75 per 1000) and Manitoba (1.68-2.39 per 1000), while rates remained relatively stable elsewhere. OAT use was highest among adults aged 25-44 years, males, and residents of lower-income neighbourhoods. A notable shift toward buprenorphine prescribing was observed across all provinces, with 45%-74% of OAT recipients dispensed a buprenorphine product in 2022. These cross-provincial differences in OAT rates likely reflect variations in opioid use disorder prevalence, prescribing practices, and access to care.