Changing patterns of opioid agonist therapy prescribing in a network of specialised clinics providing care to people who inject drugs in Victoria, Australia, 2018 to 2023

Author: Joshua Dawe, Anna Lee Wilkinson, Michael Curtis, Jason Asselin, Charles Henderson, Eric Makoni, Paul Dietze, Margaret Hellard, Mark Stoové, on behalf of the EC Victoria Partnership and the Australian Collaboration for Coordinated Enhanced Sentinel Surveillance of Blood Borne Viruses and Sexually Transmissible Infections (ACCESS)

Theme: Epidemiology & Public Health Research Year: 2024

Background: Long-acting injectable buprenorphine (LAIB) is a treatment option that avoids the need for supervised dosing of opioid agonist therapy (OAT). Limited data exists on the changing patterns of OAT prescribing in Australia after the introduction of government-subsidised LAIB in September 2019. This study describes trends in OAT prescribing between 2018 and 2023 across a network of specialist clinics in Victoria, Australia.

Methods: We used electronic medical record data from 17 primary care clinics providing specialist services to people who inject drugs within a sentinel surveillance network. We described patterns of prescribing over time for methadone, sublingual buprenorphine, and LAIB. Descriptive analyses explored trends in the annual number and type of OAT prescriptions issued, the number of individuals prescribed, and the number of individuals initiating OAT in that calendar year within the network.

Results: Between 2018 and 2023, the average annual number of OAT prescriptions issued within the network was 49,093 (range 45,893–51,733), and was highest in 2020 with 51,733 prescriptions issued. The average number of OAT recipients per year was 6,820 (range 6,595–7,205), and was highest in 2023 with 7,205 recipients. Buprenorphine (sublingual and LAIB) prescribing increased from 36% of all OAT prescribed in 2018 to 48% in 2023; LAIB increased from 12% (2,167/18,270) of buprenorphine prescribed in 2018 to 50% (10,952/22,027) in 2023. Among individuals initiating OAT within calendar years, methadone prescribing decreased from 49% (616/1,265) in 2018 to 27% (304/1,146) in 2023. Conversely, LAIB prescribing increased from 7% (71/1,078) in 2019 to 32% (362/1,146) in 2023 among individuals initiating OAT.

Conclusion: The Australian state of Victoria experienced large changes in OAT prescribing patterns between 2018 and 2023, with substantial shifts away from methadone to LAIB. Alongside ongoing monitoring of prescribing patterns, future research is needed to determine how these changes impact drug use, health, and psychosocial outcomes.

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