Abstract
Background and AimsThe 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.DesignDynamic modeling.Setting and participantsA cohort of 49 359 individuals who ever received OAT in NSW from 2001 to 2018.MeasurementsReceipt 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.FindingsAmong 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.ConclusionThe 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.
Highlights
World-wide, nearly 500 000 deaths in 2019 were directly related to drug use, of which nearly 100 000 were caused by opioid use disorders (OUD) [1, 2]
A similar ecological study in Baltimore found no association between number on opioid agonist treatment (OAT) and number of heroin-related deaths from 1995 to 1999 but a significant inverse association from 2003 to 2009, which coincided with the scale-up of buprenorphine (a 13-fold increase during this period, while the number of overdose deaths decreased by nearly twofold [16])
Dynamic modeling has not been used to evaluate historic OAT program impact, which is key to producing rigorous evidence of its population-level effectiveness and on the factors driving it needed to informing policy
Summary
World-wide, nearly 500 000 deaths in 2019 were directly related to drug use, of which nearly 100 000 were caused by opioid use disorders (OUD) [1, 2]. While the individual-level efficacy of OAT on reducing mortality has been established and quantified in meta-analyses [5, 6], demonstrating its effect at population-level has been more challenging. Such evidence is key to support and inform scale-up of OAT programs globally, which is urgently needed, as most programs reach only a small proportion of those in need [14]. Dynamic modeling has not been used to evaluate historic OAT program impact, which is key to producing rigorous evidence of its population-level effectiveness and on the factors driving it needed to informing policy.
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