Ten-year longitudinal study of incarceration among a community-based cohort of people who inject drugs

People who inject drugs are over-represented among incarcerated populations. However, there are few studies elucidating patterns of incarceration among people who inject drugs, especially among community-based cohorts. Furthermore, data on drug use and injecting risk behaviours in carceral settings are limited globally. We aimed to describe lifetime patterns of incarceration, as well as drug use and injecting risk behaviours while incarcerated, among a cohort of people who inject drugs in Melbourne, Australia (SuperMIX), stratified by key demographics. Baseline and annual follow-up interviews conducted between 2008 and 2021 collected data on demographics, drug use, health service use and criminal justice system interactions from 1328 participants. We report a descriptive account of lifetime incarceration and incarceration episode characteristics (including duration and drug use). We also compared the health and social characteristics of people who inject drugs by self-reported incarceration history. We found a high prevalence of incarceration, with 67% reporting a lifetime incarceration. Prevalence of recent incarceration remained above 20% across the 10-year follow-up. Participants with a history of incarceration showed higher rates of marginalisation and over-representation of Aboriginal and Torres Strait Islander people. Nearly one-fifth of incarceration episodes involved injecting drug use, with a majority (75%) of these episodes involving syringe sharing while incarcerated. Results show minimal progress in reducing incarceration rates among people who inject drugs, especially Aboriginal people. Our findings point to the urgent need for evidence-based harm reduction programs in carceral settings, as well as broader policy reform to reduce the over-incarceration of people who use drugs.