Modeling the population‐level impact of opioid agonist treatment on mortality among people accessing treatment between 2001 and 2020 in New South Wales, Australia

Abstract

Background and Aims The individual‐level effectiveness of opioid agonist treatment (OAT) in reducing mortality is well established, but there is less evidence on population‐level benefits. We use modeling informed with linked data from the OAT program in New South Wales (NSW), Australia, to estimate the impact of OAT provision in the community and prisons on mortality and the impact of eliminating excess mortality during OAT initiation/discontinuation. Design Dynamic modeling. Setting and participants A cohort of 49 359 individuals who ever received OAT in NSW from 2001 to 2018. Measurements Receipt of OAT was represented through five stages: (i) first month on OAT, (ii) short (1–9 months) and (iii) longer (9+ months) duration on OAT, (iv) first month following OAT discontinuation and (v) rest of time following OAT discontinuation. Incarceration was represented as four strata: (i) never or not incarcerated in the past year, (ii) currently incarcerated, (iii) released from prison within the past month and (iv) released from prison 1–12 months ago. The model incorporated elevated mortality post‐release from prison and OAT impact on reducing mortality and incarceration. Findings Among the cohort, mortality was 0.9 per 100 person‐years, OAT coverage and retention remained high (> 50%, 1.74 years/episode). During 2001–20, we estimate that OAT provision reduced overdose and other cause mortality among the cohort by 52.8% [95% credible interval (CrI) = 49.4–56.9%] and 26.6% (95% CrI =22.1–30.5%), respectively. We estimate 1.2 deaths averted and 9.7 life‐years gained per 100 person‐years on OAT. Prison OAT with post‐release OAT‐linkage accounted for 12.4% (95% CrI = 11.5–13.5%) of all deaths averted by the OAT program, primarily through preventing deaths in the first month post‐release. Preventing elevated mortality during OAT initiation and discontinuation could have averted up to 1.4% (95% CrI = 0.8–2.0%) and 3.0% (95% CrI = 2.1–5.3%) of deaths, respectively. Conclusion The community and prison opioid agonist treatment program in New South Wales, Australia appears to have substantially reduced population‐level overdose and all‐cause mortality in the past 20 years, partially due to high retention.

A descriptive coronial study of heroin toxicity deaths in Australia, 2020–2022: Characteristics, toxicology and survival times

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Impact of Changes to the Delivery of Opioid Agonist Treatment, Introduced During the COVID-19 Pandemic, On Treatment Access and Dropout in Ireland: An Interrupted Time Series Analysis

“…Our findings would suggest that changes introduced to the delivery of OAT facilitated increased coverage of OAT in Ireland, an important protective factor for reducing overdose and all-cause mortality (Chaillon et al, 2022;Santo et al, 2021). While the study found a peak in the number of people starting treatment in April 2020, 59 % of whom had prior treatment experience, this increase in starting or re-entering OAT was not sustained in the short or long term.…”

Differences in heroin overdose deaths in Australia by age, 2020-2022: Disease and estimated survival times

“…An obvious way to provide such management is enrolment in a drug treatment programme. Enrolment in a treatment programme substantially reduces the risk of overdose and death, and also improves the health of those enrolled, particularly older people ( Chaillon et al, 2022 ; Fareed et al, 2009 ; Larney et al, 2023 ; Mannelli, 2021 ). Buprenorphine, in particular, has been demonstrated to reduce overdose mortality for older people enrolled in opioid substitution treatment, and for those with cardiovascular and respiratory disease ( Larney et al, 2023 ).…”