Risk factors of suicide in prisons: a comprehensive retrospective cohort study in France, 2017-2020

Suicide is a leading cause of death in prison and the suicide rates are several times higher in the prison population than in the general population in most countries. Of the studies that have investigated risk factors for suicide in prison, few have controlled for possible confounding factors. The aim of this study is to identify risk factors of suicide among people in French prisons, over a four-year period.

All incarcerations that occurred in France during 2017-2020 were eligible. Sociodemographic, criminal and prison characteristics were collected for each incarceration from data of the National Prison Service. Survival univariate and multivariate analyses were performed with a Cox regression model.

358,522 incarcerations were included, of which 449 ended in suicide during the follow-up. The median length of prison stay was 5.1 months. The median age at prison entry was 30 years and 95.8% of incarcerations involved men. The overall suicide rate was 173 [157-189] per 100,000 person-years. Factors associated with suicide in the multivariate model (p < 0.05) were the early stage of incarceration and in particular the first week (HR = 7.6 [5.4-10.8]), violent offences and in particular homicide (HR = 3.0 [2.1-4.2]), French (HR = 1.7 [1.2-2.4]) and other European nationalities (HR = 2.1 [1.4-3.3]), age above 40 (HR = 2.0 [1.5-2.6]), pre-trial incarceration (HR = 1.8 [1.4-2.3]), being separated (HR = 1.6 [1.1-2.3] and having a high school diploma (HR = 1.4 [1.0-1.8]).

Factors associated with suicide in prison are complex and involve individuals' criminal history as well as conditions of incarceration. These characteristics may be relevant to focus suicide prevention efforts.