Angry affect and violence in the context of a psychotic illness: a systematic review and meta-analysis of the literature.

A small but significant relationship between schizophrenia and violence is well established, but not yet fully explained. Research has highlighted anger as an important factor in precipitating actual violence in general and psychiatric populations. However, anger has not been extensively studied as a risk factor for violence in people with schizophrenia and related psychoses. We evaluated published evidence on the relationship between anger and violence in patients with schizophrenia and related psychoses by means of a systematic review of the literature. A search of main online databases from inception till January 2012 was performed and supplemented with correspondence with authors and data available online. 11 studies which measured angry affect in patients with schizophrenia who had been violent were included in the review. 5 studies with a total of 510 individuals had anger data that were suitable to be pooled in a meta-analysis in form of standardised mean difference values comparing the anger scores of the non-violent groups with violent groups. All the studies included showed significantly higher scores for anger in the violent group compared with the non-violent group with the pooled result expressed as standardised mean difference of 0.74 95% CI (0.53, 0.94) and the Z value for overall effect=7.01. The studies not included in the meta-analysis which looked at 610 individuals, were analysed descriptively and all of them reported higher scores for anger for individuals with schizophrenia who acted violently. There is a consistency of significant association between angry affect and violent behaviour in the context of psychotic illness across various study designs, settings and populations. Theoretical support already exists for this relationship and this review lends further support to explore this relationship further.