Retention of opioid agonist treatment prescribers across New South Wales, Australia, 2001-2018: Implications for treatment systems and potential impact on client outcomes.

<bold>Background: </bold>There has been much research on the efficacy and effectiveness of opioid agonist treatment (OAT), but less on its implementation and sustainability. A challenge internationally has been recruiting and retaining prescribers. This paper aims to characterise the prescribers in terms of OAT prescribing behaviours.<bold>Methods: </bold>Retrospective cohort study in New South Wales, Australia. Participants were 2199 OAT prescribers between 1 st August 2001-19th September 2018.We examined trends in initiation and cessation of OAT prescribers. Adjusted hazard ratios were calculated to estimate prescriber retention, adjusting for year of initiation, practice type, client load and treatment prescribed.<bold>Results: </bold>The rate of prescribers ceasing OAT prescribing has been increasing over time: a prescriber who initiated between 2016-2017 had over four times the risk of cessation compared with one who initiated before 2001, AHR: 4.77; [3.67-6.21]. The highest prescriber cessation rate was in prescribers who had prescribed for shorter time periods. The annual percentage of prescribers who ceased prescribing among those who prescribed for ≤5 years increased from 3% in 2001 to 20 % in 2017. By 2017 more prescribers were discontinuing prescribing than new prescribers were starting. Approximately 87 % (n = 25,167) of OAT clients were under the care of 20 % of OAT prescribers (n = 202); half had been prescribing OAT for 17+ years.<bold>Conclusions: </bold>OAT prescribing is increasingly concentrated in a small group of mature prescribers, and new prescribers are not being retained. There is a need to identify and respond to the reasons that contribute to newer prescribers to cease prescribing and put in place strategies to increase retention and broaden the base of doctors involved in such prescribing. [ABSTRACT FROM AUTHOR]