Health, social and recidivism outcomes among people who have been incarcerated in New South Wales, Australia: Study protocol and cohort profile for the Prison Outcomes STudy (POST)

<div><b>Introduction and Aims</b>: </div><div>We have been funded to examine post-incarceration health and social outcomes for all people incarcerated in New South Wales (NSW), Australia, 2000-2022; assess treatment and services for drug dependence and serious mental illness; and project impact of expanding intervention coverage. We will use a linked cohort, the Prison Outcomes STudy (POST), which we also describe. </div><div><br/></div><div><b>Design and Methods</b>: </div><div>The POST cohort was established using linked administrative data for all adults (≥18 years) admitted to full-time custody in New South Wales (NSW), 2000-2022. Custody records were probabilistically linked to 15 health, justice and mortality datasets. We report baseline sociodemographic and custody characteristics and the frequency of key post-release events. </div><div><br/></div><div><b>Results</b>: </div><div>200,486 adults, 15% women (n = 30,457), were incarcerated, with 2,282,367 person-years (PY) of follow-up and 11% (257,545PY) of follow-up spent in custody. First Nations people comprised 27% the cohort. Half (48%) of the cohort (n = 95,563) had at least one contact with community mental health services and 27% (n = 54,100) had received alcohol and other drug treatment. POST will provide population-wide evidence on health and social outcomes after custody, including the effects of treatment for drug dependence and serious mental illness. We will compare across subgroups and the outcomes of post-release service engagement. Mathematical modelling will test the impact of expanding access to care in prison and post-release on outcomes in the community.</div><div><br/></div><div><b>Conclusions</b>: </div><div>POST will inform policy and service responses across justice, health and community settings to reduce harms among people who experience incarceration. </div>