Violent offending in schizophrenia spectrum disorders preceding and following diagnosis

Objective: People affected by schizophrenia spectrum disorders are at a higher risk of offending violently. This study aims to investigate risk factors in relation to the peri-diagnostic period and possible predictors of post-diagnostic violence of people diagnosed for the first time in the public mental health system.

Methods: The study compared various risk factors for post-diagnostic violence in patients ( n = 1453) diagnosed with a schizophrenia spectrum disorder. Patients were grouped according to the occurrence of peri-diagnostic violence. Of the 246 violent offenders, 164 committed their first offence pre-diagnosis. Mental health and criminological variables were evaluated across the lifespan (median age at end of follow-up = 34.22 years, range = 17.02-55.80 years).

Results: Gender, employment, non-violent offending, family incidents, violent and non-violent victimisation, substance use, personality disorder, number of in-patient admissions and history of non-compliance differed significantly across violent and non-violent subgroups (all p ⩽ 0.01 and at least small effect size). More frequent and longer inpatient admissions were found in the violent subgroups (all p ⩽ 0.01). For the whole sample, sex, number of violent offences, non-violent offences, violent victimisation, substance use and number of inpatient admissions predicted post-diagnostic violence (χ² (6) = 188.13, p < 0.001). Among patients with a history of pre-diagnostic violence, a history of non-violent offending in the 18-month period pre-diagnosis was the strongest predictor of future violence (odds ratio = 3.08, 95% confidence interval [1.32, 7.21]).

Conclusion: At triage, violence risk assessment should consider the presence of antisocial behaviour and violent victimisation, substance use, male gender and frequency of inpatient admissions. Common treatment targets for the prevention of post-diagnostic violence include criminality and victimisation. Treatment of positive symptoms should be of greater emphasis for individuals without a history of pre-diagnostic violence.