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 )

Introduction We have been funded to examine post‐incarceration health and social outcomes for all people incarcerated in New South Wales, Australia, 2000–2022; assess treatment and services for drug dependence and serious mental illness; and project the impact of expanding intervention coverage. We will use a linked cohort, the Prison Outcomes STudy ( POST ), which we also describe. Methods The POST cohort was established using linked administrative data for all adults (≥ 18 years) admitted to full‐time custody in New South Wales, 2000–2022. Custody records were probabilistically linked to 18 health, justice and mortality datasets. We report baseline sociodemographic and custody characteristics and the frequency of key post‐release events. Results 200,486 adults, 15% women ( n = 30,698), were incarcerated, with 2,282,367 person‐years of follow‐up and 11% (257,545 person‐years) of follow‐up spent in custody. First Nations people comprised 27% of 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. Discussion and Conclusions POST will inform policy and service responses across justice, health and community settings to reduce harms among people who experience incarceration.