Modifiable risk factors found for violence in schizophrenia

By Lucy Piper, Senior medwireNews Reporter

Researchers have identified modifiable risk factors for increased violence in people with psychosis that could prove important for risk assessment and management.

"Clarification of the direction and strength of risk and protective factors for violence in individuals with psychosis may enable researchers and clinicians to improve violence prediction and management, particularly in countries without specialist services or the resources to admit potentially dangerous patients for assessment," say Seena Fazel (Oxford University, UK) and colleagues.

The team conducted a systematic review and meta-analysis, identifying 110 studies reporting on factors associated with violence in a total 45,533 adults diagnosed with schizophrenia and other psychoses, 8439 (18.5%) of whom were violent. In all, 87.8% of patients had schizophrenia, 0.4% had bipolar disorder, and 11.8% other psychoses.

For the study, 146 individual risk and protective factors were examined and then summarized into 10 domains: negative symptoms, neuropsychological, positive symptoms, treatment related, suicidality, psychopathology, premorbid, demographic, substance misuse, and criminal history.

Modifiable factors significantly associated with a high risk for violence included hostile behavior (odds ratio [OR]=2.8), poor impulse control (OR=3.3), lack of insight (OR=2.7), higher general symptom scores (OR=1.7), recent alcohol and/or drug misuse (OR=2.2 and 2.2 , respectively), and non-adherence with psychological therapies and medication (OR=6.7 and 2.0, respectively).

By contrast, negative symptoms were not significantly associated with an increased risk for violence.

The researchers note in PLoSOne that criminal history factors, as a static risk factor, were strongly associated with violence and more so than substance misuse or demographic factors. Also, victimization was among the strongest set of risk factors identified.

"Prior victimization may contribute to a 'cycle of violence' whereby people with psychosis may be victimized because they place themselves in dangerous situations as a result of their own criminal behavior," Fazel and co-workers comment.

The study findings also highlight the importance of treatment adherence in reducing the risk for violence, says the team, "and in particular therapies aimed at increasing treatment adherence."

The risk factors for violence remained largely unchanged when only cases of severe violence were examined. When focusing predominantly on inpatients, the strength of the risk factors changed but not the direction.

"This review confirms the strong association between criminal history and violence risk in psychosis and it also demonstrates that certain dynamic factors are potentially important for assessment and management of violence risk," the researchers conclude.

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