Mental health risk factors for criminal recidivism and mortality in individuals given community sentences
Keywords: prediction modelling
mortality
criminal justice
survival analysis
forensic psychiatry
epidemiology
probation
criminal recidivism
community sentence

Individuals with psychiatric disorders are overrepresented in correctional populations. Given their high prevalence, understanding the role that psychiatric disorders play in criminal behaviour is essential for achieving the primary goal of correctional systems - preventing future crime. Understanding psychiatric disorders is also relevant for mitigating potential health risks, mortality being the most serious, associated with criminal behaviour and sentencing. Despite the apparent need, very few studies have examined the association of psychiatric disorders with criminal recidivism and mortality in non-custodial populations, i.e., individuals given community sentences. The present thesis addresses this research gap and provides recommendations for evidence-based risk management of individuals with psychiatric disorders undergoing community supervision.
The thesis aimed to examine the role of psychiatric disorders as factors for criminal recidivism and mortality in individuals given community sentences and to create a simple, scalable tool for criminal recidivism risk monitoring in this population. To achieve these aims, I conducted five separate studies.
The first study was a systematic review of the recidivism rates in individuals given community sentences internationally. The review covers 28 studies with data from 19 countries. Based on this systematic review, the two-year reconviction was selected as the primary criminal recidivism outcome in the present thesis. The second study reports the meta-analysis of existing research on risk factors for criminal recidivism in individuals given community sentences. The meta-analysis results further highlighted the lack of published research into psychiatric disorders and criminal recidivism in community sentenced populations. The strength of reported associations between mental health risk factors and criminal recidivism was comparable to that of non-modifiable risk factors, such as age, gender, and criminal history. However, the studies reporting these associations had major limitations, which I addressed in the third study.
The third study examined the association between psychiatric disorders and criminal recidivism in a Swedish population cohort of adult individuals given community sentences (N = 82,415) using register data. Psychiatric disorders were associated with an increased risk of both general and violent reoffending. This association persisted in individuals matched with their sentenced siblings without a known psychiatric diagnosis. Schizophrenia spectrum disorders, personality disorders and substance use disorders had stronger effects on violent reoffending than other psychiatric disorders. Comorbid substance use fully mediated the association between psychiatric disorders and general reoffending. However, comorbid substance use only partially mediated the association between psychiatric disorders and violent reoffending. In addition, first-time psychiatric diagnosis during the follow-up period was associated with a higher risk of general and violent reoffending.
The fourth study additionally examined the association between psychiatric disorders and mortality in a Swedish total population cohort of adult individuals given community sentences (N = 109,751) using register data. The leading cause of death in the cohort was suicide. Having substance use or any other psychiatric disorder at the time of a sentence or receiving a new diagnosis during the follow-up was associated with an increased risk of all-cause and external-cause mortality in the study cohort. Comorbid substance use partially mediated the association of psychiatric disorders with mortality.
The fifth study used pre-specified criminal, sociodemographic, and clinical risk factors to develop a dynamic prediction model for criminal recidivism in individuals under community supervision. The model was deployed as an online dynamic risk assessment tool OxMore with good calibration and discrimination performance (c-index = 0.74 for violent reoffending, c-index = 0.69 for general reoffending). As an important secondary outcome, the study demonstrated that actuarial recidivism risk assessment tools, which have not been developed as risk monitoring instruments but are used as such, will systematically overestimate the risk of recidivism over time.
The thesis emphasises the role of substance use and other psychiatric disorders as important targets for intervention in individuals given community sentences. Addressing psychiatric disorders in this population could potentially prevent many cases of reoffending and improve the long-term health outcomes decreasing the burden on correctional and healthcare systems. The period of community supervision should be viewed as a major opportunity window for rehabilitation and reintegration of sentenced individuals with a psychiatric disorder. Other recommendations include an increase in integrative mental health research in community sentenced populations and a more extensive application of dynamic prediction modelling for actuarial recidivism prediction.