Self-harm and suicide are common among prison inmates, but less is known about these phenomena in those with psychosis.

The aim of this study was to examine self-harm behaviour in New South Wales (NSW) prisons in Australia among inmates diagnosed with psychosis. This study also examined self-harm-related alerts applied by Corrective Services to assist staff with the management of the security and well-being of inmates.

A retrospective case-control data-linkage study was conducted using administrative data collections in NSW, Australia.

The study included all individuals diagnosed with psychosis and incarcerated between 2001 and 2020 in NSW as cases and an age and sex matched control group with no such diagnosis with a record of incarceration in the same time period.

The primary outcome measure was self-harm among the cases and controls. The secondary outcome measure was the application of alerts by Corrective Services in relation to self-harm incidents.

Multivariate regression analysis was used to examine predictors of self-harm in prison. Prisoners with psychosis (n=14 900) were more likely to self-harm than controls (n=2713), with 15.0% versus 3.6% engaging in self-harm (highest odds of self-harm observed in those with schizophrenia and related psychoses, aOR=4.84, 95% CI: 3.93 to 5.98). Those of Aboriginal heritage had an increased risk of self-harm (aOR=1.58, 95% CI: 1.43 to 1.75). Factors associated with a lower risk of self-harm were male sex and older age (≥25 years) at the time of their first incarceration. 35.6% of those released from prison with a prior psychosis diagnosis had at least one alert applied during incarceration compared with 10.1% of prisoners without a diagnosis of psychosis. Overall, 35 individuals with psychosis and 1 individual from the control group died while in prison between 2001 and 2020. 17 prison suicides were recorded from the study population; all occurred in the psychosis group.

Given the heightened risk of self-harm in those with histories of psychosis, consideration should be given to sharing mental health information between agencies to improve the care and management of this group during incarceration. Prison alerts may be a useful tool to help staff manage inmates’ well-being if used appropriately.