Mentally disordered offenders: A case linkage study of criminal justice and mental health populations in the UK

There are very few large population studies combining information from mental health and criminal justice populations and therefore a lack of information about the characteristics, risks, and service utilisation of the mentally disordered offender population as a whole. This study, for the first time in the UK, combines anonymised data to link all cases across mental health agency (n = 27,282) and criminal justice agency (n = 23,740) populations within one English county (n = 907,524) over three years. It compares gender and age characteristics of the shared population of mentally disordered offenders with each sub-population and the general county population as a whole. It assesses the risks of offending for mental and non-mental health sub-populations, both overall (six times greater among the mentally disordered) and across genders and age groups (greater among males and youngsters). It assesses the impact of mental health needs and service use on the risks and frequency of offending for different gender and age groups of mental health patients (inpatients were at higher risks and community care patients at lower risks, except for males). Finally it identifies the existence of two distinct 'care' populations and examines how this type of data could inform future service development.