Absolute and relative risk of violent victimisation and perpetration following onset of mental illness: a Danish...

Previous research has suggested that people with severe mental illness are at elevated risk of both violence perpetration and violent victimisation, with risk of the latter being perhaps greater than the former. However, few studies have examined risk across both outcomes.

Using a total population approach, the absolute and relative risks of victimisation and perpetration were estimated for young men and women across the full psychiatric diagnostic spectrum. Information on mental disorder status was extracted from national registers and information on violent victimisation and perpetration outcomes from police records. The follow-up was from age 15 to a maximum of 31 years, with most of the person-time at risk pertaining to cohort members aged in their early twenties. Both absolute risk (at 1 and 5 years from onset of illness) and relative risk were estimated.

Both types of violent outcome occurred more frequently amongst those with mental illness than the general population. However, whether risk of one was greater than the other depended on a range of factors, including sex and diagnosis. Men with a mental disorder had higher absolute risks of both outcomes than women [victimisation: C = 7.15 (6.88-7.42) versus C = 4.79 (4.61-4.99); perpetration: C = 8.17 (7.90-8.46) versus C = 1.86 (1.75-1.98)], as was the case with persons in the general population without a recorded mental illness diagnosis. Women with mental illness had higher absolute risk of victimisation than perpetration, which was also true for men and women without mental illness. However, the opposite was true for men with mental illness. Men and women with diagnoses of personality disorders, substance use disorders, and schizophrenia-spectrum disorders were at highest risk of victimisation and perpetration.

Strategies developed to prevent violent victimisation and violence perpetration may need to be tailored for young adults with mental disorders. There may also be a benefit in taking a sex-specific approach to prevention in this group.

This study was supported by an Australian National Health and Medical Research Council Investigator Grant awarded to the first author.