A retrospective records study of patterns in mental health and criminal justice service use by people found not criminally responsible on account of mental disorder.

Background: While the presence or absence of previous healthcare and criminal justice system (CJS) contacts in the histories of mentally ill offenders has been well-studied, the frequency of these contacts and when they occur in the period leading up to an index criminal event has received less research attention.

Aims: To explore patterns of healthcare and CJS use in the year prior to a criminal act leading to a Not Criminally Responsible on Account of Mental Disorder (NCRMD) finding in Canada.

Methods: In this 3-year retrospective records study, the case files of all patients newly admitted to the British Columbia forensic psychiatric system after a finding of NCRMD between 1st July 2012 and 31st July 2015 were reviewed. Data were extracted on healthcare and CJS use for the 12 months before the act leading to the NCRMD finding. Time-based descriptive statistics and two-step cluster analysis were used to investigate service use patterns.

Results: Among 94 eligible patients, only four had no service contacts in the year leading up to the index event, leaving 90 in the cohort for further analysis. On average, these 90 patients had seven contacts with health or criminal justice services in the year prior to the index offence. Cluster analysis revealed a high healthcare pathway group who had had many healthcare and few CJS contacts; a limited service user group who had had few contacts of any kind and a heavy service user group who had had a high volume of contacts with both types of service providers.

Conclusions: The different patterns of patient contact prior to the index event imply that each practitioner-type has distinct and temporally relevant opportunities to provide preventative interventions to their patients or user groups.