Risk of being subjected to crime, including violent crime, after onset of mental illness:A Danish national registry study using police data

Importance: People with mental illness are more likely to have contact with the criminal justice system, but research to date has focused on risk of offense perpetration, while less is known about risk of being subjected to crime and violence.Objectives: To establish the incidence of being subjected to all types of criminal offenses, and by violent crimes separately, after onset of mental illness across the full diagnostic spectrum compared with those in the population without mental illness.Design, Setting, and Participants: This investigation was a longitudinal national cohort study using register data in Denmark. Participants were a cohort of more than 2 million persons born between 1965 and 1998 and followed up from 2001 or from their 15th birthday until December 31, 2013. Analysis was undertaken from November 2016 until February 2018.Exposures: Cohort members were followed up for onset of mental illness, recorded as first contact with outpatient or inpatient mental health services. Diagnoses across the full spectrum of psychiatric diagnoses were considered separately for men and women.Main Outcomes and Measures: Incidence rate ratios (IRRs) were estimated for first subjection to crime event (any crime and violent crime) reported to police after onset of mental illness. The IRRs were adjusted for cohort member's own criminal offending, in addition to several sociodemographic factors.Results: In a total cohort of 2 058 063 (48.7% male; 51.3% female), the adjusted IRRs for being subjected to crime associated with any mental disorder were 1.49 (95% CI, 1.46-1.51) for men and 1.64 (95% CI, 1.61-1.66) for women. The IRRs were higher for being subjected to violent crime at 1.76 (95% CI, 1.72-1.80) for men and 2.72 (95% CI, 2.65-2.79) for women. The strongest associations were for persons diagnosed as having substance use disorders and personality disorders, but significant risk elevations were found across almost all diagnostic groups examined.Conclusions and Relevance: Onset of mental illness is associated with increased risk of exposure to crime, and violent crime in particular. Elevated risk is not confined to specific diagnostic groups. Women with mental illness are especially vulnerable to being subjected to crime. Individual's own offending accounts for some but not all of the increased vulnerability to being subjected to crime.