Rates, Timing and Correlates of Suicide in Norwegian Prisons: A 23-Year National Cohort Study

Suicide is a major public health concern, disproportionately impacting society's most vulnerable, including people in prison. Given the multifactorial etiology of suicide within correctional settings, a comprehensive investigation is critical. We aimed to examine timing of suicide according to imprisonment and associations with sociodemographic, criminological, and clinical factors, in a national prison population over two decades.

We used cohort data from the Norwegian Prison Release study (nPRIS) including all individuals incarcerated in Norwegian prisons in the period 1.1.2000 to 31.12.2022, linked with national registry data. The primary outcome was suicide mortality during imprisonment. We calculated crude mortality rates (CMR) to explore timing of suicide and estimated Cox proportional-hazards models to investigate factors associated with suicide in prison.

During the study period, 95 suicides were observed, the majority among men (94.7%), by hanging (83.2%), during pretrial detention (64.2%), and in high-security prisons (88.4%). Suicide risk was highest in the initial phase of incarceration, with a CMR of 414 (95% CI: 211-617) in the first week, more than triple the rate for the total period (CMR: 134, 95% CI: 107-161). Adjusted models showed strong associations with being incarcerated in a high-security prison (aHR: 3.82, 95% CI: 1.06-13.69), being on pretrial detention (aHR: 2.22, 95% CI: 1.72-2.86), and being diagnosed with severe mental illness (SMI) (aHR: 2.75, 95% CI: 1.51-5.02).

To reduce the risk of prison suicide, prevention efforts should target incarcerated individuals in the initial period of incarceration, individuals in pretrial detention and with severe mental illness.